Prevalence of Ligula intestinalis, histopathological investigation, and associated risk factors in Labeobarbus fish species at Lake Tana, Ethiopia

Prevalence of Ligula intestinalis, histopathological investigation, and associated risk factors in Labeobarbus fish species at Lake Tana, Ethiopia | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Prevalence of Ligula intestinalis, histopathological investigation, and associated risk factors in Labeobarbus fish species at Lake Tana, Ethiopia Tegegne Destaw, Mohammed Yessuf, hailu mazengia, Asnakew Mulaw Berihun, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6148899/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 May, 2025 Read the published version in BMC Veterinary Research → Version 1 posted 11 You are reading this latest preprint version Abstract Food security and employment prospects are significantly impacted by the fish industry. A cross-sectional study was conducted from February 2023 to March 2024 to determine the pathological lesions, prevalence, and associated risk factors of Ligula intestinalis on Labeobarbus fish species in Lake Tana, Ethiopia. A total of 384 Labeobarbus fish were randomly selected from the fishermen and their associations. The pathological lesions were examined using proper evisceration and post-mortem techniques. Various visceral organs, including the gonads (testes and ovaries), liver, and spleen, were collected from infected fish for histopathological examination. Gross pathological findings revealed abdominal distension, anal hemorrhage, gonads atrophy, displacement of internal organs, body emaciation, and visceral fibrosis accompanied by discoloration. Histopathological changes were observed in various organs, including the ovaries, testes, liver, and spleen. In the ovaries, the major alterations included fibrosis, infiltration of inflammatory cells, destruction, and atrophy of oocytes. In the testicular tissue, hyperemia, necrosis, fibrosis, and degeneration were detected. In the liver, vacuolar degeneration, biliary duct hyperplasia, infiltration of inflammatory cells, fibrosis, and necrosis were observed. In the spleen, exudation, hemorrhage, congestion, and fibrosis were the primary pathological alterations and deformities identified in the study. Among the total Labeobarbus fish included in this study, 62 were positive for Ligula intestinalis, indicating an overall parasite prevalence of 16.2% in Lake Tana. Fish standard length (χ² = 76.919, P = 0.001), fish weight (χ² = 50.087, P = 0.001), sampling points (χ² = 16.947, P = 0.009), and fish species (χ² = 27.73, P = 0.034) were significantly associated with Ligula intestinalis infection in Labeobarbus fish. The pathological effects of this parasite on vital organs, along with its high prevalence, have a significant impact on fish production and reproduction. Fish Histopathology Lake Tana Ligula Intestinalis Prevalence Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 INTRODUCTION The fish sector plays a crucial role in ensuring food security and creating job opportunities. Many fish farmers depend on lakes as a primary source of food and income (Nkhoswe, Bader et al. 2023 ). Fisheries benefit households and communities in various ways (Amare, Endalew et al. 2018 ). The industry supplies fish to households, generates income, and contributes to food and nutritional security both directly and indirectly (Natale, Gibin et al. 2015 ). Inland fisheries are particularly significant as a food source, and their importance is expected to grow as food security becomes an increasingly critical global issue (Noges, Anneville et al. 2018 ). Recent studies highlight the critical role of fisheries in ensuring food security and their importance in combating poverty in Ethiopia (Ulega, Mgaya et al. 2022 ). Fisheries also contribute to rapid economic growth. According to the report (Pauly and Zeller 2017 ), Ethiopia's catch fisheries generated approximately USD 14 million in 2010. In the country, fishing primarily occurs in rivers and lakes, with aquaculture emerging more recently as an additional practice. Lake Tana, located in Ethiopia's Amhara region, is one of the largest fishing sites in the country, predominantly utilized by traditional fishermen (Amare, Endalew et al. 2018 ). Lake Tana is the largest lake in Ethiopia, covering an area of 3,050 km² and holding nearly half of the country’s freshwater resources (Abera, Van Echelpoel et al. 2022 ). Several rivers, including the Gilgel-Abay, Megech, Reb, and Gumara, flow into the lake, while the Blue Nile is the only river that flows out of it (Kidane, Bruneel et al. 2019 ). Lake Tana is home to 27 fish species grouped into four families: Cichlidae, Clariidae, Nemacheilidae, and Cyprinidae. According to Mina and Mironovsky (2022), the first three families each contain one species, while the Cyprinidae family is more diverse, comprising four genera and 24 species (Kidane, Bruneel et al. 2019 ). The four genera of fish from the Cyprinidae family found in Lake Tana are Varicorhinus , Gara , Barbus , and Labeobarbus .. Lake Tana is home to four genera of fish from the Cyprinidae family: Varicorhinus, Gara, Barbus, and Labeobarbus (Zhokhov and Pugacheva 2012 ). The lake hosts the highest number of endemic Cyprinidae species in Ethiopia, including 15 endemic Labeobarbus species. These species exhibit significant ecological segregation, being differentiated by space, food resources, and time (de Graaf, Dejen et al. 2008 ). Lake Tana also supports three important and highly valued fish species: the African catfish (Clarias gariepinus), locally known as "Ambaza"; the Nile tilapia (Oreochromis niloticus), called "Kereso"; and the Labeobarbus species, referred to as "Nech Asa" (Gebreegziabher, Degefu et al. 2020 ). These fish are widely consumed by both urban and rural populations and are traded extensively within the region and in neighboring Sudan. According to Schauer et al. (2014), Lake Tana has a fishing potential of 10,000 tons annually. However, its current yield stands at 1,454 tons per year, which accounts for 25% of Ethiopia's total fish catch. Between 1998 and 2003, the fishing industry contributed an average of 7.94 million ETB annually, representing 0.03% of the regional GDP (Amare, Endalew et al. 2018 ). However fishes are affected by various infections, including parasitic infestations. Among these, Ligula intestinalis , a well-known cestode from the order Pseudophyllidea, is particularly significant. It primarily infects members of the Cyprinidae family (Wootten 2012 ). This parasite impacts fish in numerous ways, causing severe damage to vital organs and resulting in significant losses to the host species (Brown 2015 ). The larvae of Ligula intestinalis are found in many fish hosts worldwide, residing in their body cavities as plerocercoids. This is particularly common among hosts from the Cyprinidae family (Hoole, Carter et al. 2010 ). The cestode’s complex life cycle involves fish-eating birds as the final host and copepods as the first intermediate host. Fish become infected by consuming infected copepods, leading to high mortality rates. Severe infestations pose significant risks to commercial fishing operations (Trubiroha, Wuertz et al. 2009 ). Lake Tana, the largest lake in Ethiopia, is home to a diverse range of aquatic species (8). However, fish in the lake have recently been affected by various infections caused by parasites and other disease-causing organisms (17). These parasitic infestations significantly impact fish health, causing discomfort, stress, and internal bleeding. They also lead to behavioral changes and damage vital organs, resulting in mass mortality and infertility (Gabagambi, Salvanes et al. 2019 ). Infestations further reduce the market value of fish due to rejection and lead to slower growth, increased vulnerability to predators, and weight loss, all of which severely impact the fishing industry (Biswas and Ash 2021 ). Ligula intestinalis significantly affects the organs of its cyprinid fish hosts, but these impacts are not yet fully understood. Gross and histopathological findings related to this parasite are crucial for assessing its effects on organ function and overall health. This study aimed to investigate the pathological effects of L. intestinalis larvae and determine their prevalence in Labeobarbus fish species in Lake Tana, Ethiopia. MATERIALS AND METHODS Study Area The study was conducted in Bahir Dar at Lake Tana, located in the highlands of northwestern Ethiopia within the Amhara National Regional State. The lake is situated at an altitude of 1,830 meters above sea level and feeds the Blue Nile River. Geographically, it lies between 10°57ʹ–12°47ʹN latitude and 36°38ʹ–38°14ʹE longitude (Worqlul, Ayana et al. 2020 ). The basin landscape, part of Ethiopia's western plateau, includes the escarpments of South Gondar, Central Gondar, and North Gojjam. The lower plains surrounding the lake consist of wetlands. To the northeast lie the Fogera and Kunzila plains, while the east features the Dera and Bahir Dar Zuria areas. The northern region includes Gondar Zuria, and the southwest encompasses Alefa and Takusa. The basin covers a total area of 15,320 km² (Sorsa, Mamo et al. 2019 ). The Lake Tana environment follows a clear seasonal pattern, particularly with distinct dry and wet periods. Winter temperatures range from 19°C between January and March, while during May and June, they reach up to 24°C. Lake Tana is home to various fish families, including Cichlidae, Clariidae, Nemacheilidae, and Cyprinidae (Ageze and Menzir 2018 ). Among these fish families, Cyprinidae is one of the dominant families in the lake, with several genera, including Gara, Varicorhinus, Barbus, and Labeobarbus (Goshu and Aynalem 2017 ). The present study focused on fish from the family Cyprinidae, specifically the genus Labeobarbus as show on (Fig. 1 ). Study Animal The study focuses on Labeobarbus fish, which belong to the Cyprinidae family. The targeted fish were obtained from the fishermen's association at Lake Tana through purchase. First of all, the fishermen were members of a certified association recognized by the governmental agricultural authority. They were responsible for catching the fish and supplying them to hotels. As researchers, we purchased the sampled fish directly from them for our study. From each selected fisherman, Labeobarbus fish were randomly chosen from their fish stores. The selected fish were then transported to the laboratory for postmortem examination and the collection of targeted organs for histopathological evaluation. Sample Size Determination and Study Design A cross-sectional study design was used to determine the prevalence of Ligula intestinalis larvae in Labeobarbus fish species in Lake Tana. Therefore, the source of study fishes (labeobarbus fish) were found from Lake Tana which is a natural lake stands first among Ethiopia lakes. Some visceral organs (gonads, liver, and spleen) from infected fish were collected for histopathological studies. The total sample size for the prevalence study was calculated using the formula provided by Thrusfield (2017). For the prevalence of Ligula intestinalis larvae in Labeobarbus fish species in Lake Tana, a 50% expected prevalence was used to calculate the sample size as follows: n= (z) 2 (p) (1-p) /d 2 Where; n- required sample size; z- The standard deviation = 1.96; p- Expected prevalence; d- Desired level of precision (5%). A 95% confidence interval with the desired absolute 5% precision. A total of 384 Labeobarbus fish were sampled for this study. All 62 infected fish with L. intestinalis were included, and the visceral organs (gonads, liver, and spleen) from each infected fish were dissected and collected for histopathological studies. Sampling method The Labeobarbus fish species were randomly collected from fishermen and the fishermen's association at Lake Tana using scoop nets and minnow traps. Each fish was clearly labeled with the sampling date, location within the lake, and time of collection. The fishes were then immediately transported in water boxes to maintain the welfare of the fish to the Bahir Dar Fishery and Aquatic Life Research Center Laboratory, where their weight, standard length, sex, and species were recorded. Before conducting anatomical measurements and postmortem examinations, we ensured the welfare of the sampled fish by employing a humane euthanasia method. Due to the unavailability of chemical anesthetics, we used cervical dislocation, a physical method that involves the rapid severing of the spinal cord just behind the head. This technique is particularly effective and is recognized for its quick and humane action. Fish body measurement Prior to the post-mortem examination, each fish sample was visually assessed, and pertinent clinical signs and parameters were recorded. This included external color changes, abdominal distension, anal hemorrhage, length and weight measurements, species identification, sex determination, and age estimation. These observations were conducted at the Bahir Dar Fishery and Aquatic Life Research Center Laboratory. Postmortem examination A postmortem examination conducted using appropriate postmortem kits and a standard evisceration and incision technique to assess the gross pathological alteration of the abdominal cavity and the internal organs of the fish (Gardner, Deeming et al. 2015 ). The fish organs were examined thoroughly by keeping them wet throughout the procedure. The abdominal wall was opened from the anus up to the thoracic cavity along the ventral midline by inserting a sharp end of scissors. The detached part of the abdominal wall was removed, and after this, we collected 62 samples from each of the gonads, livers, and spleens for histopathological examination, as described by Gardner et al. ( 2015 ). Parasite identification The larvae of the parasites were collected from the abdominal cavity of the fish and fixed in 10% buffered formalin. The samples were then transported to the Veterinary Pathology and Clinical Pathology Laboratory at the University of Gondar. There, they were washed in distilled water for 24 hours and stored in 70% ethanol prior to identification. The larvae, preserved in 70% ethanol, were gradually transferred to water and then slowly differentiated in 0.5% hydrochloric acid (HCl) in 70% ethanol for a period of 1 to 12 hours, depending on the size of the larvae. Finally, the larvae were manually counted and recorded according to established protocols (Nazarizadeh, Peterka et al. 2022 ). Tissue histopathology assessment The gonads (testes and ovaries), liver, and spleen are collected from the infected fish's abdominal cavity. The tissues were cut into pieces of approximately 4–5 mm and placed in 10% buffered formalin. A 1:10 ratio of fixative to tissue was maintained in a universal sampling bottle. The samples were then transported to the University of Gondar Veterinary Pathology and Clinical Pathology Laboratory, where they were processed using a Leica automatic tissue processor (Leica, Germany), according to standard protocols (Rašković, Stanković et al. 2011 ). Tissue processing for histopathology All sampled tissues were cut to approximately 1 cm in length and labeled with tags. The tissues were rinsed with tap water to remove formaldehyde and then passed through increasingly concentrated alcohol solutions to dehydrate them. After dehydration, the alcohol was replaced with xylene in two changes for clearing. For impregnation, the tissues were placed in two changes of molten wax at 60°C. The samples were then embedded in this molten wax, using paper boats for support. Next, the tissues were mounted in wax on wooden tissue blocks, preparing them for sectioning with a microtome. We cut 5 µm thick sections using a microtome (Leica, Germany) (Talukder, Haque et al. 2007 ). The sections were placed in a hot water bath to stretch, then mounted on labeled glass slides and allowed to dry. This procedure follows the standard histopathological method for tissue processing as described by Talukder et al. ( 2007 ). Data Management and Analysis After being entered into an Excel spreadsheet and thoroughly error-checked, the data were exported to SPSS version 23 for processing and analysis. Descriptive statistics, including frequency and percentage, were utilized to characterize the prevalence of the parasite. The gross and histological lesions were described and illustrated with photographs. The relationship between risk factors and L. intestinalis infection was analyzed using the chi-square test (χ²), with a P-value of less than 0.05 considered statistically significant. RESULTS Gross Pathological result of fish L. intestinalis The gross pathological examination revealed abdominal distension, body emaciation, and fluid accumulation in the abdominal cavity. Additionally, fibrosis, inflammation, and atrophy were observed, which damaged the internal organs. The pressure exerted by the parasite larvae displaced the organs from their normal anatomical positions, often accompanied by the accumulation of bloody ascitic fluid. These were the common pathological findings recorded (Fig. 2). Histopathological alterations of gonads Various histopathological alterations were observed in the gonads. Concerning the ovaries, findings included fibrosis, infiltration of inflammatory cells, atrophy, and destruction of oocytes with degenerative and necrotic changes (atresia). Proliferative changes in the granuloma of the oocytes, along with adhesion of the cellular coat of the oocytes, hemorrhage between the oocytes, and intravascular hemolysis in some ovarian blood vessels, were also noted. Additionally, focal areas of necrosis, aggregations of hemosiderin between the oocytes, karyolysis, karyorrhexis, and separation of the follicular layers from the oocytes were observed (Fig.3 and 4). In the testicular tissues, we observed necrosis, fibrosis, and degeneration, along with a hyperemic condition (Fig. 5). Degenerative and necrotic changes were noted in the cellular components of the seminiferous tubules, which inhibited spermatogenesis. Some tubules exhibited reduced sperm counts or appeared translucent, indicating a lack of active spermatogenesis. Additionally, we identified focal areas of necrosis and the presence of fibrous capsules surrounding certain seminiferous tubules (Fig. 6). Histopathological alterations of liver The liver exhibited various histopathological abnormalities, including necrosis, patchy nuclear degeneration, blood congestion, biliary duct hyperplasia, and vacuolization with small lipid droplets and exudation (Fig. 7). Inflammation led to the infiltration of inflammatory cells. Histopathological alterations of spleen The white pulp of a normal fish spleen consists of lymphoid tissue that surrounds small arteries and intermingles with the red pulp, which is made up of a network of cells and blood-filled sinusoids. This tissue contains various cell populations, including macrophages and lymphocytes. Histopathological examination has revealed several changes, including exudation, edema, severe vacuolation, and hemorrhages. Additionally, early granuloma formation, cell necrosis, and inflammation were observed. Other noted alterations in the spleen include necrosis, fibrosis, and congestion (Fig.8). Prevalence and Associated Risk Factors In this study, 62 of the fish examined were found to be infected with L. intestinalis larvae, resulting in an overall prevalence of 16.2% at Lake Tana. Additionally, a chi-square analysis was performed to evaluate the relationship between fish length, weight, species, and the sampling locations concerning the L. intestinalis parasite. The analysis revealed that the highest prevalence of L. intestinalis (46.0%) was found in fish measuring between 5 and 20 cm in length, followed by a prevalence of 9.2% in the 21 to 29 cm range. Significant differences in parasite infection rates were observed across different size categories (c² = 76.919; P = 0.001). Number of L. Intestinalis larvae per fish at Lake Tana Fish in Lake Tana are significantly affected by parasites. This study focused on Labeobarbus fish infected by L. intestinalis larvae, with particular emphasis on the more pronounced effects on the fish's reproductive organs compared to other organs. The parasite burden was measured by counting the larvae present in each fish, revealing variations among different fish species that influenced their behavior, organ health, stress levels, and overall parasite load. Out of the 62 fish that tested positive for infection, 57 (92%) contained one larva, 4 (6%) had two, and only 1 (2%) had three larvae (Fig.9). In terms of weight, a higher prevalence of 40.0% was recorded in fish weighing between 51 and 100 grams, while the prevalence was 27.5% for those weighing between 101 and 150 grams. This weight variable also showed significant differences among its categories (c² = 50.087; P = 0.001) related to L. intestinalis infection. Regarding sampling points, the highest prevalence was noted at the Gerima wetland and Gerima, with rates of 27.5% and 23.7%, respectively. In contrast, the Fogera sampling point had the lowest prevalence at 0.0%. The analysis further indicated significant differences in prevalence among the sampling points (c² = 16.947; P = 0.009) for L. intestinalis, as shown in Table 1. Table 1 : Prevalence and Association risk factors of L. Intestinalis in Labeobarbus. Variables N o of sample examined N o of sample infected Prevalence (%) c 2 (P- value) Fish standard length (cm) 5 - 20 87 40 46.0 76.919 (0.001) 21 - 29 238 22 9.2 30 and above 59 0 0 Fish weight (gm) 50 - 100 25 10 40.0 50.087 (0.001) 101 - 150 80 22 27.5 151 - 200 118 28 23.7 201 - 250 41 2 4.9 > 250 120 Sample points on Lake Tana Aregawi 50 6 12 16.947 (0.009) Fogera 30 Debere Mariam 70 6 8.6 Gerima wet land 54 14 25.9 Gerima 62 15 24.2 Kiberan 48 10 20.8 South gulf 70 11 15.7 Total 384 62 16.2 The infection rate in Labeobarbus intermedius was 29.41%, which is higher than the rate in Labeobarbus brevicephalus at 23.66%. In contrast, neither Labeobarbus dainelli nor Labeobarbus platydorsus showed any signs of infection. The analysis indicated a significant association, with a chi-square value of 27.73 and a p-value of 0.034, linking the species of Labeobarbus and Labeobarbus intestinalis, both of which were found to have parasitic larvae infections in Tana (Table 2). Table 2 : Association between species of Labeobarbus fish and L. Intestinalis Variables N o of sample examined N o of sample infected Prevalence (%) c 2 (P- value) Labeobarbus Species 27.73 (0.034) L. Acutirostr 23 1 4.34 L. Brevicephalus 86 20 23.66 L. Crassibarbis 29 3 10.34 L. Dainelli 4 0 0 L. Gorgorenesis 24 1 4.17 L. Gorguari 17 2 11.76 L. Intermedius 68 20 29.41 L. Longissimus 31 2 6.45 L. Macrophtalmus 17 1 5.89 L. Megastoma 19 4 21.05 L. Nedgia 10 1 10 L. Platydorsus 8 0 0 L. Surkis 11 1 9.09 L. Truttiformis 24 4 16.67 L. Tsanensis 13 2 15.38 Total 384 62 16.2 DISCUSSION The study found that a gross examination revealed the impact of L. intestinalis on the fish. Observations included abdominal swelling, body wasting, fibrosis, inflammation, and atrophy of organs. Additionally, there was displacement of internal organs. The disease affected various visceral organs in different ways, showing a swollen liver and spleen, an enlarged gallbladder containing excess fluid, and missing or damaged gonads. These findings are consistent with previous reports (Bozorgnia, Omidzahir et al. 2016 )), (Gebremedhin, Mingist et al. 2012 )), and (Moradi, Bakar et al. 2011 ), indicating changes in the organs of infected fish due to compression and deformation caused by the parasite. The histopathological examination in this study revealed fibrosis, inflammatory cell infiltration, oocyte atrophy, and destruction in the ovaries, as well as hyperemia, necrosis, and degeneration in the testicular tissues. These findings are consistent with previous studies (Moradi, Bakar et al. 2011 ). Pathological observations in infected fish show signs of immature gonads, degenerative changes in follicles, hemorrhage, inflammation, cell infiltration, atrophy, and fibrosis in both the testes and ovaries. These changes may be caused by inflammation, the presence of melanomacrophages, and the infiltration of lymphocytes into the ovarian and testicular tissue. This process can ultimately lead to fibrosis and atrophy, resulting in a failure of ovulation and spermatogenesis. L. intestinalis impacts liver tissue, leading to vacuolar degeneration, infiltration of inflammatory cells, and hyperemia. The study also noted biliary duct hyperplasia, necrosis, and fibrosis. Cholangiohepatitis and metaplastic hyperplasia were observed in the liver, along with deformities and dysfunction in liver cells, as well as vacuolar degeneration. These changes were attributed to the compressive effects of L. intestinalis . This is supported by the finding (Kaur and Pandey 2014 ), (Rahmati-Holasoo, Hajimohammadi et al. 2011 ), (Mousavi, Behtash et al. 2011 ) and (Steckert, Cardoso et al. 2018 ). This research investigated the pathological changes on the spleen through histopathological analysis, where hemorrhages, multifocal necrosis, and infiltration of inflammatory cells are evident. Additionally, fibrosis and congestion are observed the spleen of the fishes. The results of this study agree with (Matsche, Blazer et al. 2023 ). However, current research findings argue, the research finding as stated that the study identified various spleen transformations, including hemorrhaging, fibrosis, congestion, and exudation due to Ligula intestinalis (David and Kartheek 2015 ). In this research, the prevalence of L. intestinalis in labeobarbus fish at Lake Tana was identified to be 16.2%, which aligns with previous findings (Ahmadiara 2017 ). However, our study revealed a lower prevalence compared to rates documented by other researchers (Tizie, Baye et al. 2014 ) found 29.0%, (Headey, Dereje et al. 2014 ) found 31.4%, (Dzerzhinskii, Shkil et al. 2007 ) found 38.46%, and (Barzegar and Jalali 2009 ) found 43%. This variation may result from Seasonal changes can affect water temperature and breeding cycles, all of which influence fish behavior and population dynamics. Different species exhibit unique behaviors, life cycles, and responses to environmental factors, resulting in variability in study outcomes. Additionally, differences in study design, data collection methods, and analysis techniques can significantly impact the findings of various studies. The study found that 2.5% of female fish and 4.2% of male fish were infected with Ligula intestinalis. In contrast, the infection rate among fish with unknown sex was significantly higher, at 83.9%. The inability to determine the sex of these fish complicated the evaluation of any potential association between gender and the illness. These findings supported by (Yilmaz, Mehmet et al. 2015 ) and (Emaminew Tizie, Dereje Baye et al. 2014 ). The high prevalence of infection in unidentified fish is linked to the disease's impact on the gonads, which can result in total organ loss. The infection rate was comparable in both male and female fish; however, assessing the rate in fish with undetermined sex was complicated due to the involvement of the affected sex organs. The current study presented a significant correlation between the size and weight of fish, as well as the sampling locations, fish species, and the prevalence of L. intestinalis in Lake Tana. The research revealed a strong association between standard length and L. intestinalis, a finding supported by (Tizie, Baye et al. 2014 ) and (Shargh, Shamsaii et al. 2008 ). This could be attributed to the concentration of small and medium fish near the upper and border areas of the lakes, where birds and copepods are more plentiful, and their immune systems are not yet fully developed. However, this contrasts with the findings of (Anteneh, Getahun et al. 2013 ) who reported a higher prevalence of L. intestinalis in larger fish. Smaller fish are less efficient in capturing infected copepods, while larger fish face a greater risk of parasite infection. The statistical significant association of the parasite with different weight categories observed by the present study was supported by (Shargh, Shamsaii et al. 2008 ) (Emaminew Tizie, Dereje Baye et al. 2014 ) who reported the prevalence was high in small weight fish compared to heavy weight. This may be due to an immature and not fully developed immune system, which makes individuals more susceptible to various diseases. The study revealed that seven locations on Lake Tana showed varying rates of parasitic infections, demonstrating a clear correlation between these locations and the level of infection. Many researchers supported this finding, suggesting that the proximity of fish processing areas to the sampling sites played a significant role. Additionally, the high presence of birds contaminating the water with offal further contributed to the increased spread and prevalence of diseases. Among the fish species studied, Labeobarbus brevicephalus and Labeobarbus intermidus exhibited higher infection rates, while Labeobarbus dainelli and Labeobarbus platydorsus remained unaffected by infection. The finding support Emaminew et al. (2014). In this investigation, the parasite burden was observed as follows: out of 62 infected fish, 57 (92%) had one larva, 4 (6%) had two larvae, and 1 (2%) had three larvae. on Barbus in Lake Tana, where 83 (94.5%) were infected with one larva and 4 (5.5%) with two larvae. These findings align with previous reports (Emaminew Tizie, Dereje Baye et al. 2014 ). CONCLUSIONS Lake Tana is a vital source of fish for the country; however, it faces several challenges, including parasitic infections. L. intestinalis causes notable gross and histopathological changes, particularly harming the gonads, liver, and spleen, which ultimately compromise the overall health of the fish. Approximately 16.2% of fish in Lake Tana are affected by L. intestinalis, leading to behavioral changes that increase their vulnerability to predators, thereby threatening the fish population. The problem is further worsened by outdated fish processing methods, pollution, improper disposal of fish parts, and poor management practices in the lake. Therefore, it is crucial to implement preventive and monitoring programs to break the cycle of infection and mitigate its impact on the lake ecosystem and the fish industry. Declarations Funding Not applicable Ethical consideration The current study has been approved for its ethical soundness for the time from February 2023 to March 2024 by the Institutional Ethical Review Board (IRB) of the College of Veterinary Medicine and Animal Sciences, University of Gondar, Ethiopia. It has been given at reference (Reference No: CVMAS.Sc.16.282025). Acknowledgements Not applicable Author’s Contribution Tegegne Destaw collected the sample in the field and processed the laboratory work. Mohammed Yessuf Supervise the proposal and he commented on the work of laboratory Hailu Mazengia organized data and performed the analysis. Asnakew Mulaw Berihun and Mengesha Ayehu Getnet reviewed the manuscript. All authors checked and approved the final draft of the manuscript. Consent of the farmers and local fisher men: We obtained the consent of the farmers after conducting discussions and meetings to raise awareness about the research objectives and its benefits. All the farmers voluntarily participated in the study. After selecting the fish for the research, we compensated each farmer for the cost of their fish. Primarily, the study fish (Labeobarbus species) were sourced from Lake Tana, the largest natural lake in Ethiopia and the sample fishes were bought from those fishery men. To ensure the welfare of the sampled fish used for necropsy and tissue sampling, we employed a humane euthanasia method. Due to the unavailability of chemical anesthetics, we used a physical method—cervical dislocation—which involves the rapid severing of the spinal cord just behind the head which is (<3 cm) and is recognized for its quick and humane action. By adopting this approach, we ensured a rapid and ethical euthanasia process while addressing the challenges posed by the lack of chemical alternatives. Availability of data and materials All authors are ready to give the available data to the readers by requesting via email and any communication platform. 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"Land constraints and agricultural intensification in Ethiopia: A village-level analysis of high-potential areas." Food Policy 48 : 129-141. Hoole, D., V. Carter and S. Dufour (2010). "Ligula intestinalis (Cestoda: Pseudophyllidea): an ideal fish-metazoan parasite model?" Parasitology 137 (3): 425-438. Kaur, P. and S. Pandey (2014). "Effect on marketability of ornamental fishes due to parasitic infection." Biolife 2 (4): 1094-1099. Kidane, S. G., S. Bruneel, A. Getahun, W. Anteneh and P. Goethals (2019). "The endemic species flock of Labeobarbus spp. in L. Tana (Ethiopia) threatened by extinction: implications for conservation management." WATER 11 (12). Matsche, M. A., V. S. Blazer and E. L. Pulster (2023). "White perch health relative to urbanization and habitat degradation in Chesapeake Bay tributaries. II. Hepatic and splenic macrophage aggregates." Diseases of Aquatic Organisms 154 : 107-130. Moradi, Y., J. Bakar, A. Motalebi, S. Syed Muhamad and Y. Che Man (2011). "A review on fish lipid: Composition and changes during cooking methods." Journal of Aquatic Food Product Technology 20 (4): 379-390. Mousavi, H. E., F. Behtash, M. Rostami-Bashman, S. S. Mirzargar, P. Shayan and H. Rahmati-holasoo (2011). "Study of Argulus spp. infestation rate in Goldfish, Carassius auratus (Linnaeus, 1758) in Iran." Human and Veterinary Medicine 3 (3): 198-204. Natale, F., M. Gibin, A. Alessandrini, M. Vespe and A. Paulrud (2015). "Mapping fishing effort through AIS data." PloS one 10 (6): e0130746. Nazarizadeh, M., J. Peterka, J. Kubecka, M. Vašek, T. Juza, K. R. de Moraes, M. Cech, M. Holubová, A. T. Souza and P. Blabolil (2022). "Different hosts in different lakes: prevalence and population genetic structure of plerocercoids of Ligula intestinalis (Cestoda) in Czech water bodies." Nkhoswe, J., S. Bader, E. Nyauchi, Y. Lemma, O. Geoffrey and A. Geremew (2023). "Sustainability of the Sub-Saharan African Capture Fisheries and Aquaculture Value Chains: A Review of the Roles and Challenges of Youths and Women in Ethiopia, Kenya, Malawi and Zambia." International Journal of Research and Innovation in Social Science 7 (12): 1643-1674. Noges, T., O. Anneville, J. Guillard, J. Haberman, A. Jarvalt, M. Manca, G. Morabito, M. Rogora, S. J. Thackeray and P. Volta (2018). "Fisheries impacts on lake ecosystem structure in the context of a changing climate and trophic state." Journal of limnology 77 (1): 46-61. Pauly, D. and D. Zeller (2017). "Comments on FAOs state of world fisheries and aquaculture (SOFIA 2016)." Marine Policy 77 : 176-181. Rahmati-Holasoo, H., B. Hajimohammadi, E. Ahmadiara, H. E. Mousavi, M. Rostami-bashman, A. K. Asl, I. S. Haghdoost, S. Shokrpoor and A. Ghorbanalipour (2011). "A study of infestation of Alburnoides bipunctatus with Ligula intestinalis in Latian reservoir Dam Lake, Tehran province, Iran: a histopathological study." Human and Veterinary Medicine 3 (1): 18-24. Rašković, B., M. Stanković, Z. Marković and V. Poleksić (2011). "Histological methods in the assessment of different feed effects on liver and intestine of fish." Journal of Agricultural Sciences (Belgrade) 56 (1): 87-100. Shargh, S., M. Shamsaii and S. Karimi (2008). "Distribution of Parasitic Cestod" Ligula intestinalis" in Ma-zandaran Region." Iranian Journal of Parasitology 3 (2): 26-33. Sorsa, M., G. Mamo and L. Abera (2019). "Major fish-borne bacterial and parasitic zoonoses in Ethiopia: A review." Int. J. Fauna Biol. Stud 6 : 50-58. Steckert, L. D., L. Cardoso, G. T. Jerônimo, S. B. de Pádua and M. L. Martins (2018). "Investigation of farmed Nile tilapia health through histopathology." Aquaculture 486 : 161-169. Talukder, S., M. Haque, M. Huq, M. Alam, A. Roushan, Z. Noor and K. Nahar (2007). "Histopathological analysis of hysterectomy specimens." Mymensingh Medical Journal: MMJ 16 (1): 81-84. Tizie, E., D. Baye and A. Mohamed (2014). "Prevalence of Ligula intestinalis larvae in Barbus fish genera at Lake Tana, Ethiopia." World J Fish Marine Sci 6 (6): 408-416. Trubiroha, A., S. Wuertz, S. N. Frank, B. Sures and W. Kloas (2009). "Expression of gonadotropin subunits in roach (Rutilus rutilus, Cyprinidae) infected with plerocercoids of the tapeworm Ligula intestinalis (Cestoda)." International Journal for Parasitology 39 (13): 1465-1473. Ulega, A., Y. Mgaya, R. Lokina and R. Mushy (2022). "The Contribution of Marine Fisheries to Socio-economic Development in Tanzania Mainland: Reflections on the Blue Economy Concept from Selected Coastal Villages." Journal of the Geographical Association of Tanzania 42 (2): 1-22. Wootten, R. (2012). "The parasitology of teleosts." Fish pathology : 292-338. Worqlul, A. W., E. K. Ayana, Y. T. Dile, M. A. Moges, M. G. Dersseh, G. Tegegne and S. Kibret (2020). "Spatiotemporal dynamics and environmental controlling factors of the Lake Tana water hyacinth in Ethiopia." Remote Sensing 12 (17): 2706. Yilmaz, Ö., C. Mehmet, S. Kelekci and M. Temur (2015). "Association between red blood cell distribution width and polycystic ovary syndrome." Endocrine research 40 (4): 181-187. Zhokhov, A. and M. Pugacheva (2012). "Distribution and occurrence of Ligula intestinalis (L.) plerocercoids (Cestoda, Ligulidae) in the fishes of Lake Tana, Ethiopia." Inland Water Biology 5 : 293-298. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 30 May, 2025 Read the published version in BMC Veterinary Research → Version 1 posted Editorial decision: Revision requested 15 Apr, 2025 Reviews received at journal 11 Apr, 2025 Reviews received at journal 05 Apr, 2025 Reviewers agreed at journal 04 Apr, 2025 Reviewers agreed at journal 02 Apr, 2025 Reviewers agreed at journal 02 Apr, 2025 Reviewers invited by journal 02 Apr, 2025 Editor assigned by journal 02 Apr, 2025 Editor invited by journal 31 Mar, 2025 Submission checks completed at journal 28 Mar, 2025 First submitted to journal 28 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6148899","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":437784977,"identity":"e22a317b-7544-4066-81da-4bcc4af24811","order_by":0,"name":"Tegegne Destaw","email":"","orcid":"","institution":"University of Gondar","correspondingAuthor":false,"prefix":"","firstName":"Tegegne","middleName":"","lastName":"Destaw","suffix":""},{"id":437784978,"identity":"5206f805-3189-4328-9c45-e536626cbc60","order_by":1,"name":"Mohammed Yessuf","email":"","orcid":"","institution":"University of Gondar","correspondingAuthor":false,"prefix":"","firstName":"Mohammed","middleName":"","lastName":"Yessuf","suffix":""},{"id":437784979,"identity":"03acd906-1f8e-49dc-9ff3-6c8766637e21","order_by":2,"name":"hailu mazengia","email":"","orcid":"","institution":"Bahir Dar University","correspondingAuthor":false,"prefix":"","firstName":"hailu","middleName":"","lastName":"mazengia","suffix":""},{"id":437784980,"identity":"1df55f2b-55d0-4e59-8da3-33d773e10a86","order_by":3,"name":"Asnakew Mulaw Berihun","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIiWNgGAWjYNACg5r6fvYGEMOCaC3HGGf2HAAxJIi2hplxw4wEEIMILbrtxx8+LihgYzaQfH51w48CCQb+9u4EvFrMzuQYG88wkGEzl84pu9kDdJjEmbMb8Gs5kMMmzWPAxmM5OyftBg9Qi4FELgEt558//81jwCxhcPNM2s0/RGm5kWDGDNRiYHCD/dht4my58cYY6LBjCZI9OWy3ZQwkeAj75Xz6w888f2oS+NmPP7v55o+NHH97L34tSIDHAEwSqxwE2B+QonoUjIJRMApGEAAA2h9FSubU/sgAAAAASUVORK5CYII=","orcid":"","institution":"University of Gondar","correspondingAuthor":true,"prefix":"","firstName":"Asnakew","middleName":"Mulaw","lastName":"Berihun","suffix":""},{"id":437784981,"identity":"c6f23ca1-76b0-48e7-b7f3-aa9a8c943212","order_by":4,"name":"Mengeshan Ayehu Getnet","email":"","orcid":"","institution":"University of Gondar","correspondingAuthor":false,"prefix":"","firstName":"Mengeshan","middleName":"Ayehu","lastName":"Getnet","suffix":""}],"badges":[],"createdAt":"2025-03-03 19:53:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6148899/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6148899/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12917-025-04799-5","type":"published","date":"2025-05-30T15:57:38+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":79887926,"identity":"c81267f1-9def-45b4-a7cd-f4fa651b2c1e","added_by":"auto","created_at":"2025-04-04 06:30:58","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":62874,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGeographical location of the Lake Tana associated with Bahir Dar town, rivers and road (Source: Geographic Information System, 2023).\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/aea106b47024bac3dcb4c292.png"},{"id":79887110,"identity":"b9673ad9-c9a9-4c40-b929-6569f8624aa0","added_by":"auto","created_at":"2025-04-04 06:22:58","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":104592,"visible":true,"origin":"","legend":"\u003cp\u003eFish gross pathological findings.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA\u003c/strong\u003e: Fluid accumulation in the abdominal cavity (Red arrow), and displacement of internal organ (Yellow arrow), internal organ fibrosis, liver and spleen attached to abdominal wall; \u003cstrong\u003eB\u003c/strong\u003e: abdominal distention (Red arrow); \u003cstrong\u003eC\u003c/strong\u003e: larvae isolated (Red arrow); \u003cstrong\u003eD\u003c/strong\u003e: emaciation mussel (Red arrow).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/2fb35a67929fa7c19cafa401.png"},{"id":79887115,"identity":"fa1b7121-cb78-4865-bd31-1fadbe065b72","added_by":"auto","created_at":"2025-04-04 06:22:58","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":257014,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMicrographs of ovary histological sections. \u003c/strong\u003eNote: Fibrosis (Green arrow), infiltration of inflammatory cells (Yellow arrow), atrophy and destruction of oocytes (Black arrow), inflammatory cells in blood vessel (Red arrow), necrosis of the central lumen (Blue arrow), necrosis (Blue Black arrow) (H \u0026amp;E, 10X, 40X, 40X, and 100X magnifications respectively).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/cfbd9122a8594dda5b50d6ba.png"},{"id":79887113,"identity":"6e43542e-3760-4fec-9a9a-9131189c953e","added_by":"auto","created_at":"2025-04-04 06:22:58","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1089116,"visible":true,"origin":"","legend":"\u003cp\u003eMicrographs of ovary histological sections.\u003c/p\u003e\n\u003cp\u003eNote: Degenerative, and necrotic zona radiate (Blue black arrow), granulosa of the oocytes (Blue arrow), adhesion of the cellular coat (Blue arrow), necrosis (Blue black arrow), karyolysis (Black arrow), karyorrhexis (Yellow arrow), atrophy and destruction of oocytes (Green arrow), (H and E, 40X, 40X, 40X and 10X magnifications respectively).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/e01f8f531ed5603012e180eb.png"},{"id":79887119,"identity":"e1486743-453d-4e89-a7af-941bda6b4f86","added_by":"auto","created_at":"2025-04-04 06:22:58","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":731188,"visible":true,"origin":"","legend":"\u003cp\u003eMicrographs of testicular histopathological tissue sections.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eNote:\u003c/strong\u003e\u003cem\u003e \u003c/em\u003e\u0026nbsp;Hyperemia (Yellow arrow), Fibrosis central lumen (Red arrow), Fibrosis interstitial tissue (Blue arrow), Blood cells (White arrow), degenerative and necrotic changes in the cellular elements of seminiferous tubules (Green arrow), (H \u0026amp;E: 4X, 10X, 40X and 100X magnifications respectively).\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/78c7e394b516de622f43ec89.png"},{"id":79887117,"identity":"815d8692-54a1-48c0-b6b7-7755179ccff7","added_by":"auto","created_at":"2025-04-04 06:22:58","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":257870,"visible":true,"origin":"","legend":"\u003cp\u003eMicrographs of testicular histopathological tissue sections:\u003c/p\u003e\n\u003cp\u003eNote: degenerative and necrotic of seminiferous tubules (Green arrow), focal areas of necrosis in central lumen (Yellow arrow), Central efferent duct fibrosis (Black arrow), malformation and distortion (Blue arrow), (H and E, 4X, 10X, 40X, 40X respectively magnifications).\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/6c6ae33631064b17dd03d294.png"},{"id":79887125,"identity":"01b9bf9b-c26e-4689-84bd-731f1de7adf3","added_by":"auto","created_at":"2025-04-04 06:22:58","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":1471596,"visible":true,"origin":"","legend":"\u003cp\u003eMicrographs of liver histopathological sections\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNote: fibrosis (Blue arrow), vacuolar degeneration (Back arrow), and blood vessel (Yellow arrow), and infiltration of inflammatory cells (Black arrow), biliary duct hyperplasia (Green arrow), and necrosis (Orange arrow); Exudation (Blue black arrow), nucleus degeneration (Red arrow); (H \u0026amp; E, 10X, 40X, 40, 100X magnifications respectively).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/474c72c789caf7d30640777f.png"},{"id":79887934,"identity":"97d5a2ad-3ec0-4400-a40d-b93c5333ee96","added_by":"auto","created_at":"2025-04-04 06:30:59","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":298514,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMicrographs of spleen histopathological sections:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNote: infiltration of inflammatory cells (Green arrow), necrosis (Blue black arrow), fibrosis (Yellow arrow), congested (Black arrow), exudation (Blue arrow), multi lymphocytic cell necrosis (Red arrow) and granuloma tissue (Yellow circle) (H \u0026amp; E, 10X, 40X, 100X, 100X magnifications respectively).\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/565b6028d0e14fb6d7946ac6.png"},{"id":79887126,"identity":"55737e83-ee3b-4c18-abee-9e30259511cd","added_by":"auto","created_at":"2025-04-04 06:22:59","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":27433,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eNumber of L. Intestinalis larvae per fish at Lake Tana.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/60a8fdb4de4ed626bca3bbb2.png"},{"id":83782895,"identity":"77857012-f542-4025-81fd-9d8f4d1f5802","added_by":"auto","created_at":"2025-06-02 16:08:13","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5513859,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6148899/v1/63e60db6-59fe-4122-a92a-ef043b52d630.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Prevalence of Ligula intestinalis, histopathological investigation, and associated risk factors in Labeobarbus fish species at Lake Tana, Ethiopia","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eThe fish sector plays a crucial role in ensuring food security and creating job opportunities. Many fish farmers depend on lakes as a primary source of food and income (Nkhoswe, Bader et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Fisheries benefit households and communities in various ways (Amare, Endalew et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The industry supplies fish to households, generates income, and contributes to food and nutritional security both directly and indirectly (Natale, Gibin et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Inland fisheries are particularly significant as a food source, and their importance is expected to grow as food security becomes an increasingly critical global issue (Noges, Anneville et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eRecent studies highlight the critical role of fisheries in ensuring food security and their importance in combating poverty in Ethiopia (Ulega, Mgaya et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Fisheries also contribute to rapid economic growth. According to the report (Pauly and Zeller \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), Ethiopia's catch fisheries generated approximately USD 14\u0026nbsp;million in 2010. In the country, fishing primarily occurs in rivers and lakes, with aquaculture emerging more recently as an additional practice. Lake Tana, located in Ethiopia's Amhara region, is one of the largest fishing sites in the country, predominantly utilized by traditional fishermen (Amare, Endalew et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLake Tana is the largest lake in Ethiopia, covering an area of 3,050 km\u0026sup2; and holding nearly half of the country\u0026rsquo;s freshwater resources (Abera, Van Echelpoel et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Several rivers, including the Gilgel-Abay, Megech, Reb, and Gumara, flow into the lake, while the Blue Nile is the only river that flows out of it (Kidane, Bruneel et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLake Tana is home to 27 fish species grouped into four families: Cichlidae, Clariidae, Nemacheilidae, and Cyprinidae. According to Mina and Mironovsky (2022), the first three families each contain one species, while the Cyprinidae family is more diverse, comprising four genera and 24 species (Kidane, Bruneel et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The four genera of fish from the Cyprinidae family found in Lake Tana are \u003cem\u003eVaricorhinus\u003c/em\u003e, \u003cem\u003eGara\u003c/em\u003e, \u003cem\u003eBarbus\u003c/em\u003e, and \u003cem\u003eLabeobarbus\u003c/em\u003e.. Lake Tana is home to four genera of fish from the Cyprinidae family: Varicorhinus, Gara, Barbus, and Labeobarbus (Zhokhov and Pugacheva \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). The lake hosts the highest number of endemic Cyprinidae species in Ethiopia, including 15 endemic Labeobarbus species. These species exhibit significant ecological segregation, being differentiated by space, food resources, and time (de Graaf, Dejen et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLake Tana also supports three important and highly valued fish species: the African catfish (Clarias gariepinus), locally known as \"Ambaza\"; the Nile tilapia (Oreochromis niloticus), called \"Kereso\"; and the Labeobarbus species, referred to as \"Nech Asa\" (Gebreegziabher, Degefu et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). These fish are widely consumed by both urban and rural populations and are traded extensively within the region and in neighboring Sudan. According to Schauer et al. (2014), Lake Tana has a fishing potential of 10,000 tons annually. However, its current yield stands at 1,454 tons per year, which accounts for 25% of Ethiopia's total fish catch. Between 1998 and 2003, the fishing industry contributed an average of 7.94\u0026nbsp;million ETB annually, representing 0.03% of the regional GDP (Amare, Endalew et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). However fishes are affected by various infections, including parasitic infestations. Among these, \u003cem\u003eLigula intestinalis\u003c/em\u003e, a well-known cestode from the order Pseudophyllidea, is particularly significant. It primarily infects members of the Cyprinidae family (Wootten \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). This parasite impacts fish in numerous ways, causing severe damage to vital organs and resulting in significant losses to the host species (Brown \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe larvae of \u003cem\u003eLigula intestinalis\u003c/em\u003e are found in many fish hosts worldwide, residing in their body cavities as plerocercoids. This is particularly common among hosts from the Cyprinidae family (Hoole, Carter et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). The cestode\u0026rsquo;s complex life cycle involves fish-eating birds as the final host and copepods as the first intermediate host. Fish become infected by consuming infected copepods, leading to high mortality rates. Severe infestations pose significant risks to commercial fishing operations (Trubiroha, Wuertz et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLake Tana, the largest lake in Ethiopia, is home to a diverse range of aquatic species (8). However, fish in the lake have recently been affected by various infections caused by parasites and other disease-causing organisms (17). These parasitic infestations significantly impact fish health, causing discomfort, stress, and internal bleeding. They also lead to behavioral changes and damage vital organs, resulting in mass mortality and infertility (Gabagambi, Salvanes et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eInfestations further reduce the market value of fish due to rejection and lead to slower growth, increased vulnerability to predators, and weight loss, all of which severely impact the fishing industry (Biswas and Ash \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLigula intestinalis significantly affects the organs of its cyprinid fish hosts, but these impacts are not yet fully understood. Gross and histopathological findings related to this parasite are crucial for assessing its effects on organ function and overall health. This study aimed to investigate the pathological effects of L. intestinalis larvae and determine their prevalence in Labeobarbus fish species in Lake Tana, Ethiopia.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Area\u003c/h2\u003e \u003cp\u003e The study was conducted in Bahir Dar at Lake Tana, located in the highlands of northwestern Ethiopia within the Amhara National Regional State. The lake is situated at an altitude of 1,830 meters above sea level and feeds the Blue Nile River. Geographically, it lies between 10\u0026deg;57ʹ\u0026ndash;12\u0026deg;47ʹN latitude and 36\u0026deg;38ʹ\u0026ndash;38\u0026deg;14ʹE longitude (Worqlul, Ayana et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The basin landscape, part of Ethiopia's western plateau, includes the escarpments of South Gondar, Central Gondar, and North Gojjam. The lower plains surrounding the lake consist of wetlands. To the northeast lie the Fogera and Kunzila plains, while the east features the Dera and Bahir Dar Zuria areas. The northern region includes Gondar Zuria, and the southwest encompasses Alefa and Takusa. The basin covers a total area of 15,320 km\u0026sup2; (Sorsa, Mamo et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe Lake Tana environment follows a clear seasonal pattern, particularly with distinct dry and wet periods. Winter temperatures range from 19\u0026deg;C between January and March, while during May and June, they reach up to 24\u0026deg;C. Lake Tana is home to various fish families, including Cichlidae, Clariidae, Nemacheilidae, and Cyprinidae (Ageze and Menzir \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Among these fish families, Cyprinidae is one of the dominant families in the lake, with several genera, including Gara, Varicorhinus, Barbus, and Labeobarbus (Goshu and Aynalem \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). The present study focused on fish from the family Cyprinidae, specifically the genus Labeobarbus as show on (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eStudy Animal\u003c/p\u003e \u003cp\u003eThe study focuses on Labeobarbus fish, which belong to the Cyprinidae family. The targeted fish were obtained from the fishermen's association at Lake Tana through purchase. First of all, the fishermen were members of a certified association recognized by the governmental agricultural authority. They were responsible for catching the fish and supplying them to hotels. As researchers, we purchased the sampled fish directly from them for our study. From each selected fisherman, Labeobarbus fish were randomly chosen from their fish stores. The selected fish were then transported to the laboratory for postmortem examination and the collection of targeted organs for histopathological evaluation.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSample Size Determination and Study Design\u003c/h3\u003e\n\u003cp\u003eA cross-sectional study design was used to determine the prevalence of Ligula intestinalis larvae in Labeobarbus fish species in Lake Tana. Therefore, the source of study fishes (labeobarbus fish) were found from Lake Tana which is a natural lake stands first among Ethiopia lakes. Some visceral organs (gonads, liver, and spleen) from infected fish were collected for histopathological studies. The total sample size for the prevalence study was calculated using the formula provided by Thrusfield (2017). For the prevalence of Ligula intestinalis larvae in Labeobarbus fish species in Lake Tana, a 50% expected prevalence was used to calculate the sample size as follows:\u003c/p\u003e \u003cp\u003en= \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e(z)\u003c/span\u003e \u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e2\u003c/span\u003e\u003c/sup\u003e \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e(p) (1-p)\u003c/span\u003e/d\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eWhere; n- required sample size; z- The standard deviation\u0026thinsp;=\u0026thinsp;1.96; p- Expected prevalence; d- Desired level of precision (5%). A 95% confidence interval with the desired absolute 5% precision.\u003c/p\u003e \u003cp\u003eA total of 384 Labeobarbus fish were sampled for this study. All 62 infected fish with L. intestinalis were included, and the visceral organs (gonads, liver, and spleen) from each infected fish were dissected and collected for histopathological studies.\u003c/p\u003e \u003cp\u003eSampling method\u003c/p\u003e \u003cp\u003eThe Labeobarbus fish species were randomly collected from fishermen and the fishermen's association at Lake Tana using scoop nets and minnow traps. Each fish was clearly labeled with the sampling date, location within the lake, and time of collection. The fishes were then immediately transported in water boxes to maintain the welfare of the fish to the Bahir Dar Fishery and Aquatic Life Research Center Laboratory, where their weight, standard length, sex, and species were recorded. Before conducting anatomical measurements and postmortem examinations, we ensured the welfare of the sampled fish by employing a humane euthanasia method. Due to the unavailability of chemical anesthetics, we used cervical dislocation, a physical method that involves the rapid severing of the spinal cord just behind the head. This technique is particularly effective and is recognized for its quick and humane action.\u003c/p\u003e \u003cp\u003eFish body measurement\u003c/p\u003e \u003cp\u003ePrior to the post-mortem examination, each fish sample was visually assessed, and pertinent clinical signs and parameters were recorded. This included external color changes, abdominal distension, anal hemorrhage, length and weight measurements, species identification, sex determination, and age estimation. These observations were conducted at the Bahir Dar Fishery and Aquatic Life Research Center Laboratory.\u003c/p\u003e\n\u003ch3\u003ePostmortem examination\u003c/h3\u003e\n\u003cp\u003eA postmortem examination conducted using appropriate postmortem kits and a standard evisceration and incision technique to assess the gross pathological alteration of the abdominal cavity and the internal organs of the fish (Gardner, Deeming et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The fish organs were examined thoroughly by keeping them wet throughout the procedure. The abdominal wall was opened from the anus up to the thoracic cavity along the ventral midline by inserting a sharp end of scissors. The detached part of the abdominal wall was removed, and after this, we collected 62 samples from each of the gonads, livers, and spleens for histopathological examination, as described by Gardner et al. (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eParasite identification\u003c/h3\u003e\n\u003cp\u003eThe larvae of the parasites were collected from the abdominal cavity of the fish and fixed in 10% buffered formalin. The samples were then transported to the Veterinary Pathology and Clinical Pathology Laboratory at the University of Gondar. There, they were washed in distilled water for 24 hours and stored in 70% ethanol prior to identification. The larvae, preserved in 70% ethanol, were gradually transferred to water and then slowly differentiated in 0.5% hydrochloric acid (HCl) in 70% ethanol for a period of 1 to 12 hours, depending on the size of the larvae. Finally, the larvae were manually counted and recorded according to established protocols (Nazarizadeh, Peterka et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eTissue histopathology assessment\u003c/h3\u003e\n\u003cp\u003eThe gonads (testes and ovaries), liver, and spleen are collected from the infected fish's abdominal cavity. The tissues were cut into pieces of approximately 4\u0026ndash;5 mm and placed in 10% buffered formalin. A 1:10 ratio of fixative to tissue was maintained in a universal sampling bottle. The samples were then transported to the University of Gondar Veterinary Pathology and Clinical Pathology Laboratory, where they were processed using a Leica automatic tissue processor (Leica, Germany), according to standard protocols (Rašković, Stanković et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTissue processing for histopathology\u003c/p\u003e \u003cp\u003eAll sampled tissues were cut to approximately 1 cm in length and labeled with tags. The tissues were rinsed with tap water to remove formaldehyde and then passed through increasingly concentrated alcohol solutions to dehydrate them. After dehydration, the alcohol was replaced with xylene in two changes for clearing. For impregnation, the tissues were placed in two changes of molten wax at 60\u0026deg;C. The samples were then embedded in this molten wax, using paper boats for support. Next, the tissues were mounted in wax on wooden tissue blocks, preparing them for sectioning with a microtome. We cut 5 \u0026micro;m thick sections using a microtome (Leica, Germany) (Talukder, Haque et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). The sections were placed in a hot water bath to stretch, then mounted on labeled glass slides and allowed to dry. This procedure follows the standard histopathological method for tissue processing as described by Talukder et al. (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eData Management and Analysis\u003c/h2\u003e \u003cp\u003eAfter being entered into an Excel spreadsheet and thoroughly error-checked, the data were exported to SPSS version 23 for processing and analysis. Descriptive statistics, including frequency and percentage, were utilized to characterize the prevalence of the parasite. The gross and histological lesions were described and illustrated with photographs. The relationship between risk factors and L. intestinalis infection was analyzed using the chi-square test (χ\u0026sup2;), with a P-value of less than 0.05 considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003ch2\u003eGross Pathological result of fish L. intestinalis\u003c/h2\u003e\n\u003cp\u003eThe gross pathological examination revealed abdominal distension, body emaciation, and fluid accumulation in the abdominal cavity. Additionally, fibrosis, inflammation, and atrophy were observed, which damaged the internal organs. The pressure exerted by the parasite larvae displaced the organs from their normal anatomical positions, often accompanied by the accumulation of bloody ascitic fluid. These were the common pathological findings recorded (Fig. 2).\u003c/p\u003e\n\u003cp\u003eHistopathological alterations of gonads\u003c/p\u003e\n\u003cp\u003eVarious histopathological alterations were observed in the gonads. Concerning the ovaries, findings included fibrosis, infiltration of inflammatory cells, atrophy, and destruction of oocytes with degenerative and necrotic changes (atresia). Proliferative changes in the granuloma of the oocytes, along with adhesion of the cellular coat of the oocytes, hemorrhage between the oocytes, and intravascular hemolysis in some ovarian blood vessels, were also noted. Additionally, focal areas of necrosis, aggregations of hemosiderin between the oocytes, karyolysis, karyorrhexis, and separation of the follicular layers from the oocytes were observed (Fig.3 and 4).\u003c/p\u003e\n\u003cp\u003eIn the testicular tissues, we observed necrosis, fibrosis, and degeneration, along with a hyperemic condition (Fig. 5). Degenerative and necrotic changes were noted in the cellular components of the seminiferous tubules, which inhibited spermatogenesis. Some tubules exhibited reduced sperm counts or appeared translucent, indicating a lack of active spermatogenesis. Additionally, we identified focal areas of necrosis and the presence of fibrous capsules surrounding certain seminiferous tubules (Fig. 6).\u003c/p\u003e\n\u003ch3\u003eHistopathological alterations of liver\u003c/h3\u003e\n\u003cp\u003eThe liver exhibited various histopathological abnormalities, including necrosis, patchy nuclear degeneration, blood congestion, biliary duct hyperplasia, and vacuolization with small lipid droplets and exudation (Fig. 7). Inflammation led to the infiltration of inflammatory cells.\u003c/p\u003e\n\u003cp\u003eHistopathological alterations of spleen\u003c/p\u003e\n\u003cp\u003eThe white pulp of a normal fish spleen consists of lymphoid tissue that surrounds small arteries and intermingles with the red pulp, which is made up of a network of cells and blood-filled sinusoids. This tissue contains various cell populations, including macrophages and lymphocytes. Histopathological examination has revealed several changes, including exudation, edema, severe vacuolation, and hemorrhages. Additionally, early granuloma formation, cell necrosis, and inflammation were observed. Other noted alterations in the spleen include necrosis, fibrosis, and congestion (Fig.8).\u003c/p\u003e\n\u003ch2\u003ePrevalence and Associated Risk Factors\u003c/h2\u003e\n\u003cp\u003eIn this study, 62 of the fish examined were found to be infected with L. intestinalis larvae, resulting in an overall prevalence of 16.2% at Lake Tana. Additionally, a chi-square analysis was performed to evaluate the relationship between fish length, weight, species, and the sampling locations concerning the L. intestinalis parasite. The analysis revealed that the highest prevalence of L. intestinalis (46.0%) was found in fish measuring between 5 and 20 cm in length, followed by a prevalence of 9.2% in the 21 to 29 cm range. Significant differences in parasite infection rates were observed across different size categories (c\u0026sup2; = 76.919; P = 0.001).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eNumber of L. Intestinalis larvae per fish at Lake Tana\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFish in Lake Tana are significantly affected by parasites. This study focused on Labeobarbus fish infected by L. intestinalis larvae, with particular emphasis on the more pronounced effects on the fish\u0026apos;s reproductive organs compared to other organs. The parasite burden was measured by counting the larvae present in each fish, revealing variations among different fish species that influenced their behavior, organ health, stress levels, and overall parasite load. Out of the 62 fish that tested positive for infection, 57 (92%) contained one larva, 4 (6%) had two, and only 1 (2%) had three larvae (Fig.9).\u003c/p\u003e\n\u003cp\u003eIn terms of weight, a higher prevalence of 40.0% was recorded in fish weighing between 51 and 100 grams, while the prevalence was 27.5% for those weighing between 101 and 150 grams. This weight variable also showed significant differences among its categories (c\u0026sup2; = 50.087; P = 0.001) related to L. intestinalis infection. Regarding sampling points, the highest prevalence was noted at the Gerima wetland and Gerima, with rates of 27.5% and 23.7%, respectively. In contrast, the Fogera sampling point had the lowest prevalence at 0.0%. The analysis further indicated significant differences in prevalence among the sampling points (c\u0026sup2; = 16.947; P = 0.009) for L. intestinalis, as shown in Table 1.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTable\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cem\u003e1\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cem\u003e: Prevalence and Association risk factors of L. Intestinalis in Labeobarbus.\u003c/em\u003e\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"673\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariables\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003cu\u003eo\u003c/u\u003e of sample examined\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003cu\u003eo\u003c/u\u003e of sample infected\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePrevalence\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ec\u003csup\u003e2 \u0026nbsp;\u003c/sup\u003e(P- value)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" valign=\"top\" style=\"width: 673px;\"\u003e\n \u003cp\u003eFish standard length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e5 - 20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e46.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e76.919 (0.001)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e21 - 29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e238\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e9.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e30 and above\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" valign=\"top\" style=\"width: 673px;\"\u003e\n \u003cp\u003eFish weight (gm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e50 - 100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e40.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"6\" valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e50.087 (0.001)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e101 - 150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e151 - 200\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e118\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e23.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e201 - 250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e4.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e\u0026gt; 250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" valign=\"top\" style=\"width: 673px;\"\u003e\n \u003cp\u003eSample points on Lake Tana\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eAregawi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"7\" valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e16.947 (0.009)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eFogera\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eDebere Mariam\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e8.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eGerima wet land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e25.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eGerima\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e24.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eKiberan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e20.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eSouth gulf\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e15.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e384\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e16.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe infection rate in Labeobarbus intermedius was 29.41%, which is higher than the rate in Labeobarbus brevicephalus at 23.66%. In contrast, neither Labeobarbus dainelli nor Labeobarbus platydorsus showed any signs of infection. The analysis indicated a significant association, with a chi-square value of 27.73 and a p-value of 0.034, linking the species of Labeobarbus and Labeobarbus intestinalis, both of which were found to have parasitic larvae infections in Tana (Table 2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTable\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cem\u003e2\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cem\u003e: Association between species of Labeobarbus fish and L. Intestinalis\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"667\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariables\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003cu\u003eo\u003c/u\u003e of sample examined\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003cu\u003eo\u003c/u\u003e of sample infected\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePrevalence\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ec\u003csup\u003e2 \u0026nbsp;\u003c/sup\u003e(P- value)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 553px;\"\u003e\n \u003cp\u003eLabeobarbus Species\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" rowspan=\"16\" valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;27.73 (0.034)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Acutirostr\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e4.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Brevicephalus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e23.66\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Crassibarbis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e10.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Dainelli\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Gorgorenesis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e4.17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Gorguari\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e11.76\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Intermedius\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e29.41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Longissimus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e6.45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Macrophtalmus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e5.89\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Megastoma\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e21.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Nedgia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Platydorsus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Surkis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e9.09\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Truttiformis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e16.67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eL. Tsanensis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e15.38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 247px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e384\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e16.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe study found that a gross examination revealed the impact of L. intestinalis on the fish. Observations included abdominal swelling, body wasting, fibrosis, inflammation, and atrophy of organs. Additionally, there was displacement of internal organs. The disease affected various visceral organs in different ways, showing a swollen liver and spleen, an enlarged gallbladder containing excess fluid, and missing or damaged gonads. These findings are consistent with previous reports (Bozorgnia, Omidzahir et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2016\u003c/span\u003e)), (Gebremedhin, Mingist et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2012\u003c/span\u003e)), and (Moradi, Bakar et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), indicating changes in the organs of infected fish due to compression and deformation caused by the parasite.\u003c/p\u003e \u003cp\u003eThe histopathological examination in this study revealed fibrosis, inflammatory cell infiltration, oocyte atrophy, and destruction in the ovaries, as well as hyperemia, necrosis, and degeneration in the testicular tissues. These findings are consistent with previous studies (Moradi, Bakar et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Pathological observations in infected fish show signs of immature gonads, degenerative changes in follicles, hemorrhage, inflammation, cell infiltration, atrophy, and fibrosis in both the testes and ovaries. These changes may be caused by inflammation, the presence of melanomacrophages, and the infiltration of lymphocytes into the ovarian and testicular tissue. This process can ultimately lead to fibrosis and atrophy, resulting in a failure of ovulation and spermatogenesis.\u003c/p\u003e \u003cp\u003eL. intestinalis impacts liver tissue, leading to vacuolar degeneration, infiltration of inflammatory cells, and hyperemia. The study also noted biliary duct hyperplasia, necrosis, and fibrosis. Cholangiohepatitis and metaplastic hyperplasia were observed in the liver, along with deformities and dysfunction in liver cells, as well as vacuolar degeneration. These changes were attributed to the compressive effects of \u003cem\u003eL. intestinalis\u003c/em\u003e. This is supported by the finding (Kaur and Pandey \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), (Rahmati-Holasoo, Hajimohammadi et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), (Mousavi, Behtash et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) and (Steckert, Cardoso et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis research investigated the pathological changes on the spleen through histopathological analysis, where hemorrhages, multifocal necrosis, and infiltration of inflammatory cells are evident. Additionally, fibrosis and congestion are observed the spleen of the fishes. The results of this study agree with (Matsche, Blazer et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). However, current research findings argue, the research finding as stated that the study identified various spleen transformations, including hemorrhaging, fibrosis, congestion, and exudation due to Ligula intestinalis (David and Kartheek \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn this research, the prevalence of L. intestinalis in labeobarbus fish at Lake Tana was identified to be 16.2%, which aligns with previous findings (Ahmadiara \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). However, our study revealed a lower prevalence compared to rates documented by other researchers (Tizie, Baye et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) found 29.0%, (Headey, Dereje et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) found 31.4%, (Dzerzhinskii, Shkil et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) found 38.46%, and (Barzegar and Jalali \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) found 43%. This variation may result from Seasonal changes can affect water temperature and breeding cycles, all of which influence fish behavior and population dynamics. Different species exhibit unique behaviors, life cycles, and responses to environmental factors, resulting in variability in study outcomes. Additionally, differences in study design, data collection methods, and analysis techniques can significantly impact the findings of various studies.\u003c/p\u003e \u003cp\u003eThe study found that 2.5% of female fish and 4.2% of male fish were infected with Ligula intestinalis. In contrast, the infection rate among fish with unknown sex was significantly higher, at 83.9%. The inability to determine the sex of these fish complicated the evaluation of any potential association between gender and the illness. These findings supported by (Yilmaz, Mehmet et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) and (Emaminew Tizie, Dereje Baye et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The high prevalence of infection in unidentified fish is linked to the disease's impact on the gonads, which can result in total organ loss. The infection rate was comparable in both male and female fish; however, assessing the rate in fish with undetermined sex was complicated due to the involvement of the affected sex organs.\u003c/p\u003e \u003cp\u003eThe current study presented a significant correlation between the size and weight of fish, as well as the sampling locations, fish species, and the prevalence of L. intestinalis in Lake Tana. The research revealed a strong association between standard length and L. intestinalis, a finding supported by (Tizie, Baye et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) and (Shargh, Shamsaii et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). This could be attributed to the concentration of small and medium fish near the upper and border areas of the lakes, where birds and copepods are more plentiful, and their immune systems are not yet fully developed. However, this contrasts with the findings of (Anteneh, Getahun et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) who reported a higher prevalence of L. intestinalis in larger fish.\u003c/p\u003e \u003cp\u003eSmaller fish are less efficient in capturing infected copepods, while larger fish face a greater risk of parasite infection. The statistical significant association of the parasite with different weight categories observed by the present study was supported by (Shargh, Shamsaii et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) (Emaminew Tizie, Dereje Baye et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) who reported the prevalence was high in small weight fish compared to heavy weight. This may be due to an immature and not fully developed immune system, which makes individuals more susceptible to various diseases.\u003c/p\u003e \u003cp\u003eThe study revealed that seven locations on Lake Tana showed varying rates of parasitic infections, demonstrating a clear correlation between these locations and the level of infection. Many researchers supported this finding, suggesting that the proximity of fish processing areas to the sampling sites played a significant role. Additionally, the high presence of birds contaminating the water with offal further contributed to the increased spread and prevalence of diseases. Among the fish species studied, Labeobarbus brevicephalus and Labeobarbus intermidus exhibited higher infection rates, while Labeobarbus dainelli and Labeobarbus platydorsus remained unaffected by infection. The finding support Emaminew et al. (2014).\u003c/p\u003e \u003cp\u003eIn this investigation, the parasite burden was observed as follows: out of 62 infected fish, 57 (92%) had one larva, 4 (6%) had two larvae, and 1 (2%) had three larvae. on Barbus in Lake Tana, where 83 (94.5%) were infected with one larva and 4 (5.5%) with two larvae. These findings align with previous reports (Emaminew Tizie, Dereje Baye et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eLake Tana is a vital source of fish for the country; however, it faces several challenges, including parasitic infections. L. intestinalis causes notable gross and histopathological changes, particularly harming the gonads, liver, and spleen, which ultimately compromise the overall health of the fish. Approximately 16.2% of fish in Lake Tana are affected by L. intestinalis, leading to behavioral changes that increase their vulnerability to predators, thereby threatening the fish population. The problem is further worsened by outdated fish processing methods, pollution, improper disposal of fish parts, and poor management practices in the lake. Therefore, it is crucial to implement preventive and monitoring programs to break the cycle of infection and mitigate its impact on the lake ecosystem and the fish industry.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical consideration\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe current study has been approved for its ethical soundness for the time from February 2023 to March 2024 by the Institutional Ethical Review Board (IRB) of the College of Veterinary Medicine and Animal Sciences, University of Gondar, Ethiopia. It has been given at reference (Reference No: CVMAS.Sc.16.282025).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor\u0026rsquo;s Contribution\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTegegne Destaw collected the sample in the field and processed the laboratory work. Mohammed Yessuf Supervise the proposal and he commented on the work of laboratory Hailu Mazengia organized data and performed the analysis. Asnakew Mulaw Berihun and Mengesha Ayehu Getnet reviewed the manuscript. All authors checked and approved the final draft of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent of the farmers and local fisher men:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe obtained the consent of the farmers after conducting discussions and meetings to raise awareness about the research objectives and its benefits. All the farmers voluntarily participated in the study. After selecting the fish for the research, we compensated each farmer for the cost of their fish.\u003c/p\u003e\n\u003cp\u003ePrimarily, the study fish (Labeobarbus species) were sourced from Lake Tana, the largest natural lake in Ethiopia and the sample fishes were bought from those fishery men. To ensure the welfare of the sampled fish used for necropsy and tissue sampling, we employed a humane euthanasia method. Due to the unavailability of chemical anesthetics, we used a physical method\u0026mdash;cervical dislocation\u0026mdash;which involves the rapid severing of the spinal cord just behind the head which is (\u0026lt;3 cm) and is recognized for its quick and humane action.\u003c/p\u003e\n\u003cp\u003eBy adopting this approach, we ensured a rapid and ethical euthanasia process while addressing the challenges posed by the lack of chemical alternatives.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors are ready to give the available data to the readers by requesting via email and any communication platform.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors, we have great consent for the publication\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe declare that no conflict of interest. \u0026nbsp;\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbera, B., W. Van Echelpoel, A. De Cock, B. Tytgat, M. Kibret, P. Spanoghe, D. Mengistu, E. Adgo, J. Nyssen and P. L. Goethals (2022). \u0026quot;Environmental and human health risks of pesticide presence in the Lake Tana Basin (Ethiopia).\u0026quot; \u003cu\u003eSustainability\u003c/u\u003e \u003cstrong\u003e14\u003c/strong\u003e(21): 14008.\u003c/li\u003e\n\u003cli\u003eAgeze, N. and A. Menzir (2018). \u0026quot;Prevalence of Nematode (Contracaecum) and Cestode (Ligula intestinalis) parasites infection in two fish species at Lake Tana.\u0026quot; \u003cu\u003eJ Adv Res Pub\u003c/u\u003e \u003cstrong\u003e2\u003c/strong\u003e: 1.\u003c/li\u003e\n\u003cli\u003eAhmadiara, E. (2017). \u0026quot;Is Ligula intestinalis Really a Probable Threat for Public Health?\u0026quot; \u003cu\u003eJournal of food quality and hazards control\u003c/u\u003e \u003cstrong\u003e4\u003c/strong\u003e: 36.\u003c/li\u003e\n\u003cli\u003eAmare, D., M. Endalew, T. Debas, A. Demissew, K. Temesgen, A. Meresa and A. Getnet (2018). \u0026quot;Fishing condition and Fishers income: the case of Lake Tana, Ethiopia.\u0026quot; \u003cu\u003eInt J Aquac Fish Sci\u003c/u\u003e \u003cstrong\u003e4\u003c/strong\u003e(1): 006-009.\u003c/li\u003e\n\u003cli\u003eAnteneh, W., A. Getahun and E. Dejen (2013). \u0026quot;Spawning migrations of Lake Tana Labeobarbus spp.(Teleostei: Cyprinidae) in the Ribb River, Ethiopia.\u0026quot; \u003cu\u003eAfrican Journal of Aquatic Science\u003c/u\u003e \u003cstrong\u003e38\u003c/strong\u003e(sup1): 61-68.\u003c/li\u003e\n\u003cli\u003eBarzegar, M. and B. Jalali (2009). \u0026quot;Crustacean parasites of fresh and brackish (Caspian Sea) water fishes of Iran.\u0026quot;\u003c/li\u003e\n\u003cli\u003eBiswas, R. and A. Ash (2021). \u003cu\u003eImpact of endocrine disruption on host-parasite interaction: A digest from a cosmopolitan cestode model Ligula intestinalis\u003c/u\u003e. Proceedings of the Zoological Society, Springer.\u003c/li\u003e\n\u003cli\u003eBozorgnia, A., S. 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Kibret (2020). \u0026quot;Spatiotemporal dynamics and environmental controlling factors of the Lake Tana water hyacinth in Ethiopia.\u0026quot; \u003cu\u003eRemote Sensing\u003c/u\u003e \u003cstrong\u003e12\u003c/strong\u003e(17): 2706.\u003c/li\u003e\n\u003cli\u003eYilmaz, \u0026Ouml;., C. Mehmet, S. Kelekci and M. Temur (2015). \u0026quot;Association between red blood cell distribution width and polycystic ovary syndrome.\u0026quot; \u003cu\u003eEndocrine research\u003c/u\u003e \u003cstrong\u003e40\u003c/strong\u003e(4): 181-187.\u003c/li\u003e\n\u003cli\u003eZhokhov, A. and M. Pugacheva (2012). \u0026quot;Distribution and occurrence of Ligula intestinalis (L.) plerocercoids (Cestoda, Ligulidae) in the fishes of Lake Tana, Ethiopia.\u0026quot; \u003cu\u003eInland Water Biology\u003c/u\u003e \u003cstrong\u003e5\u003c/strong\u003e: 293-298.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-veterinary-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [BMC Veterinary Research](http://bmcvetres.biomedcentral.com/)","snPcode":"12917","submissionUrl":"https://submission.nature.com/new-submission/12917/3?","title":"BMC Veterinary Research","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Fish, Histopathology, Lake Tana, Ligula Intestinalis, Prevalence","lastPublishedDoi":"10.21203/rs.3.rs-6148899/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6148899/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFood security and employment prospects are significantly impacted by the fish industry. A cross-sectional study was conducted from February 2023 to March 2024 to determine the pathological lesions, prevalence, and associated risk factors of Ligula intestinalis on Labeobarbus fish species in Lake Tana, Ethiopia. A total of 384 Labeobarbus fish were randomly selected from the fishermen and their associations. The pathological lesions were examined using proper evisceration and post-mortem techniques. Various visceral organs, including the gonads (testes and ovaries), liver, and spleen, were collected from infected fish for histopathological examination. Gross pathological findings revealed abdominal distension, anal hemorrhage, gonads atrophy, displacement of internal organs, body emaciation, and visceral fibrosis accompanied by discoloration. Histopathological changes were observed in various organs, including the ovaries, testes, liver, and spleen. In the ovaries, the major alterations included fibrosis, infiltration of inflammatory cells, destruction, and atrophy of oocytes. In the testicular tissue, hyperemia, necrosis, fibrosis, and degeneration were detected. In the liver, vacuolar degeneration, biliary duct hyperplasia, infiltration of inflammatory cells, fibrosis, and necrosis were observed. In the spleen, exudation, hemorrhage, congestion, and fibrosis were the primary pathological alterations and deformities identified in the study. Among the total Labeobarbus fish included in this study, 62 were positive for Ligula intestinalis, indicating an overall parasite prevalence of 16.2% in Lake Tana. Fish standard length (χ\u0026sup2; = 76.919, P\u0026thinsp;=\u0026thinsp;0.001), fish weight (χ\u0026sup2; = 50.087, P\u0026thinsp;=\u0026thinsp;0.001), sampling points (χ\u0026sup2; = 16.947, P\u0026thinsp;=\u0026thinsp;0.009), and fish species (χ\u0026sup2; = 27.73, P\u0026thinsp;=\u0026thinsp;0.034) were significantly associated with Ligula intestinalis infection in Labeobarbus fish. The pathological effects of this parasite on vital organs, along with its high prevalence, have a significant impact on fish production and reproduction.\u003c/p\u003e","manuscriptTitle":"Prevalence of Ligula intestinalis, histopathological investigation, and associated risk factors in Labeobarbus fish species at Lake Tana, Ethiopia","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-04 06:22:53","doi":"10.21203/rs.3.rs-6148899/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-15T10:54:15+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-11T14:46:09+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-05T23:18:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"22367192349383048574286406744149912274","date":"2025-04-04T20:19:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"215730497079004975049348475644762662773","date":"2025-04-03T02:51:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"40873052836289610601167169839225479368","date":"2025-04-02T23:28:39+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-04-02T18:49:19+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-04-02T18:44:50+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-04-01T02:23:03+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-28T08:11:29+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Veterinary Research","date":"2025-03-28T08:10:19+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-veterinary-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [BMC Veterinary Research](http://bmcvetres.biomedcentral.com/)","snPcode":"12917","submissionUrl":"https://submission.nature.com/new-submission/12917/3?","title":"BMC Veterinary Research","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5ca88457-1d82-4d11-b7e1-fa6657dad299","owner":[],"postedDate":"April 4th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-06-02T16:02:02+00:00","versionOfRecord":{"articleIdentity":"rs-6148899","link":"https://doi.org/10.1186/s12917-025-04799-5","journal":{"identity":"bmc-veterinary-research","isVorOnly":false,"title":"BMC Veterinary Research"},"publishedOn":"2025-05-30 15:57:38","publishedOnDateReadable":"May 30th, 2025"},"versionCreatedAt":"2025-04-04 06:22:53","video":"","vorDoi":"10.1186/s12917-025-04799-5","vorDoiUrl":"https://doi.org/10.1186/s12917-025-04799-5","workflowStages":[]},"version":"v1","identity":"rs-6148899","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6148899","identity":"rs-6148899","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}