Intestinal Schistosomiasis in an Adolescent with Freshwater Exposure in Somalia: A Case Report

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Despite mass drug administration (MDA) campaigns, clinical case reports are rarely documented, limiting insights into real-world presentations and diagnostics in endemic settings. This case highlights the clinical and diagnostic approach to intestinal schistosomiasis in a Somali adolescent. Case Presentation : A 15-year-old male from an agricultural community near Mogadishu presented with a five-month history of crampy abdominal pain and blood-streaked stool. His history revealed frequent swimming and fishing in local irrigation canals. Physical examination was notable only for mild right upper quadrant tenderness. Laboratory findings demonstrated eosinophilia (0.8 × 10⁹/L). Stool microscopy via Kato-Katz technique confirmed Schistosoma mansoni infection with visible lateral-spined eggs. A point-of-care circulating cathodic antigen (POC-CCA) test was additionally positive. Abdominal ultrasonography showed no evidence of hepatosplenic morbidity. The patient was treated with praziquantel (40 mg/kg), resulting in complete resolution of symptoms within two weeks. Follow-up at six weeks confirmed parasitological clearance. Conclusion : This case underscores the importance of clinical suspicion for schistosomiasis in patients with abdominal pain and hematochezia in endemic areas, even in the absence of advanced disease. It reinforces the value of combined diagnostic tools—microscopy, serological antigen testing, and ultrasound—in resource-limited settings. Furthermore, it emphasizes that individual case management and health education remain crucial complements to community-wide MDA programs for achieving sustained control of schistosomiasis. Schistosoma mansoni intestinal schistosomiasis Somalia adolescent praziquantel Kato-Katz point-of-care CCA mass drug administration Figures Figure 1 Introduction Schistosomiasis is a neglected tropical disease caused by trematode blood flukes of the genus Schistosoma. Human infection occurs when skin contacts freshwater containing cercariae shed by infected planorbid snails— for intestinal schistosomiasis, chiefly Biomphalaria spp. Intestinal disease due to S. mansoni typically manifests with abdominal pain, diarrhoea, and blood in stool; subacute presentations may include eosinophilia and constitutional symptoms. In children and adolescents, cumulative egg deposition and intestinal inflammation are linked to anaemia, under‑nutrition, and impaired school performance, while chronic disease can progress to periportal (Symmers) fibrosis with portal hypertension and splenomegaly [ 1 ]. In the Horn of Africa, S. mansoni transmission persists in riverine and irrigation systems— including the Juba–Shabelle basins and peri‑urban canals—where routine freshwater contact (bathing, swimming, fishing, and farming) is common and WASH infrastructure is limited. Somalia remains on the WHO list of countries requiring preventive chemotherapy for schistosomiasis, underscoring ongoing risk and programme needs [ 3 , 1 ]. School‑aged children and adolescents bear the highest burden of infection and morbidity. From a clinical and public‑health standpoint, confirming S. mansoni in endemic settings relies on direct or antigen‑based detection: stool microscopy using the Kato–Katz technique documents egg excretion and intensity, while point‑of‑care circulating cathodic antigen (POC‑CCA) testing can improve case detection where egg output is low. Ultrasound following the WHO/Niamey protocol is recommended to stage hepatosplenic morbidity and guide follow‑up [ 2 , 1 , 4 , 5 ]. Against this backdrop, the present case illustrates typical exposure pathways, diagnostic confirmation, and prompt response to praziquantel in a Somali adolescent. Case presentation a 15-year-old male student living near irrigated farmland on the outskirts of Mogadishu, presented for medical evaluation with a five-month history of intermittent, crampy lower abdominal pain accompanied by blood-streaked stool. His symptoms began shortly after the rainy season, a period during which he reported frequent weekly swimming and fishing in local irrigation canals. He specifically denied experiencing any fever, weight loss, nocturnal symptoms, or urinary complaints and confirmed he had not taken any deworming medication in the past year. His past medical history was unremarkable, and his immunization status was up to date. His household relied on untreated surface water for their daily needs. No other family members reported similar symptoms. The patient was not on any regular medications and had no known drug allergies. Upon physical examination, the patient was afebrile with a temperature of 36.8°C and was haemodynamically stable, with a pulse of 84 beats per minute, a blood pressure of 108/68 mmHg, a respiratory rate of 18 breaths per minute, and an oxygen saturation of 98% on room air. He appeared well-nourished and was not in any apparent distress. There was no conjunctival pallor to suggest anemia, no peripheral edema, and his skin was warm and dry without any rash or signs of excoriation. Examination of his heart and lungs revealed normal heart sounds and clear breath sounds bilaterally. His abdomen was soft, not distended, and with normal bowel sounds; the only notable finding was mild tenderness on deep palpation in the right upper quadrant without any rebound tenderness or guarding. There was no evidence of hepatosplenomegaly, ascites, jaundice, or other signs of chronic liver disease. No peripheral lymphadenopathy was detected. A digital rectal examination was deferred due to the history of minor, self-limited bleeding, but an external inspection of the perianal area was normal. The timeline of his illness began approximately five months prior to presentation with the onset of abdominal pain and intermittent blood in his stool following his frequent swimming in the canals. His symptoms gradually worsened in frequency over the subsequent four months, prompting his visit to the clinic one month before the diagnostic tests. On the day of his clinic presentation, designated as Day 0, laboratory tests, a stool examination using the Kato-Katz method, a urine point-of-care circulating cathodic antigen (POC-CCA) test, and an abdominal ultrasound were all performed. He was immediately administered a single-day course of praziquantel at a dose of 40 mg/kg, given in two divided doses. By Day 14, his symptoms had significantly improved with no further episodes of bleeding. At a follow-up appointment six weeks later, stool microscopy was negative for S. mansoni eggs, and his abdominal ultrasound remained unchanged, showing no signs of periportal fibrosis. The diagnostic assessment revealed a key laboratory finding of eosinophilia, with an elevated eosinophil count of approximately 0.8 x 10⁹/L, a pattern highly suggestive of a helminthic infection such as acute or subacute schistosomiasis. The definitive diagnosis was confirmed by stool examination, which on wet mount preparation and duplicate Kato-Katz thick smears, revealed multiple lateral-spined eggs ( Fig. 1 ) morphologically consistent with Schistosoma mansoni . This parasitological confirmation solidly diagnosed intestinal schistosomiasis. Further supportive evidence came from a positive urine POC-CCA test, which indicates active infection and offers enhanced sensitivity, particularly in cases where egg output might be low; however, the inherent variability in the specificity of trace-positive results was noted. Serologic testing was not deemed necessary as the case occurred in an endemic area and the gold standard of direct egg detection had been achieved. A targeted abdominal ultrasound, performed according to the WHO/Niamey protocol, showed a normal hepatic echotexture, a portal vein caliber within normal limits, and no evidence of splenomegaly or the periportal fibrosis characteristic of advanced disease (Symmers' fibrosis), indicating the absence of any hepatosplenic complications at the time of presentation. Other potential diagnoses, including bacterial or amoebic dysentery, inflammatory bowel disease, intestinal polyps, haemorrhoids, or a bleeding diathesis, were considered but were deemed far less likely given the confluence of the patient's high-risk exposure to freshwater, his compatible gastrointestinal symptoms, and the direct laboratory confirmation of S. mansoni infection. The therapeutic intervention centered on the administration of praziquantel, the anthelmintic drug of choice for schistosomiasis, given at the standard total dose of 40 mg/kg orally in two divided doses over a single day. Considering the possibility that some parasites might have been immature and therefore less susceptible to the drug at the time of treatment, a plan was made to consider re-treatment after several weeks if the clinical or parasitological response was suboptimal. Supportive management was equally emphasized and included counselling the patient on maintaining adequate hydration, strict avoidance of all freshwater exposures that could harbour the infectious cercariae, and comprehensive household education on the critical importance of safe water, sanitation, and hygiene (WASH) practices to drastically limit the risk of reinfection. The treatment was well-tolerated, with the only reported adverse effect being mild, transient nausea within the first 24 hours, which resolved spontaneously without any need for intervention. At follow-up, the patient's outcomes were excellent. By day 14 ( Table 1 ), his abdominal pain had markedly improved and the rectal bleeding had completely resolved, with his appetite and energy levels returning to normal. At the six-week follow-up appointment, duplicate Kato-Katz thick smears were negative for S. mansoni eggs, confirming a parasitological cure. A repeat abdominal ultrasound again showed no signs of periportal fibrosis or splenomegaly, with the portal vein caliber remaining within normal reference limits. The patient had successfully resumed full school attendance and all his routine activities without any limitations. The family received reinforced counselling on the continued avoidance of canal water and the sustained practice of WASH principles. To ensure ongoing protection within this endemic community, the patient was registered for the next community-wide mass drug administration of praziquantel and was scheduled for continued clinical surveillance in 6 to 12 months, which would include repeat stool microscopy and an ultrasound if clinically indicated. This long-term plan acknowledges that while praziquantel is highly effective against adult worms, repeat dosing is often necessary to target maturing parasites in areas where ongoing environmental exposure is a persistent reality. Timeline Date/Interval Event Month − 5 Onset of abdominal pain and intermittent haematochezia after frequent canal swimming Month − 1 Worsening symptom frequency; clinic presentation Day 0 Labs, stool Kato–Katz, urine POC‑CCA, and abdominal ultrasound performed; praziquantel 40 mg/kg (single day, divided doses) administered Day 14 Symptom improvement; no further bleeding Week 6 Follow‑up: stool microscopy negative for S. mansoni; ultrasound unchanged (no periportal fibrosis) Discussion Our findings highlight several critical aspects of this case within the broader context of schistosomiasis control. Intestinal schistosomiasis is endemic across subSaharan Africa and remains a priority in the Horn of Africa, with Somalia designated as requiring preventive chemotherapy. Sustained transmission in Somalia is facilitated by frequent human–water contact along the Juba–Shabelle river system and periurban irrigation canals, where slowmoving freshwater supports Biomphalaria snail hosts of S. mansoni. Typical exposure routes include swimming, bathing, laundry, fishing, smallscale agriculture, and domestic water collection, activities that disproportionately involve schoolaged children and adolescents. Periodic flooding and waterscarcity cycles, rapid urbanisation, and gaps in water, sanitation and hygiene (WASH) infrastructure further amplify risk and reinfection, particularly in informal settlements and displacement settings. In this context, transmission is driven by skin contact with cercariae in freshwater bodies (rivers, lakes, canals) where compatible snail hosts are present, underscoring the need for routine deworming and integrated WASH and vectorhabitat measures [ 1 , 3 ]. Recent ESPEN sitelevel mapping for Somalia (2025) demonstrates heterogeneity in sitespecific prevalence across districts, informing targeted mass drug administration and surveillance [ 8 ]. The clinical presentation and diagnostic pathway in this case were classic for intestinal schistosomiasis. Typical manifestations include abdominal pain, diarrhoea, and blood in stool; eosinophilia is common in acute or subacute infection [ 2 ]. In this patient, the combination of high-risk exposure, crampy abdominal pain, haematochezia, and significant eosinophilia created a highly suggestive clinical picture. In endemic settings, Kato–Katz stool microscopy remains practical for confirmation and programme monitoring [ 14 ], which was successfully utilized here to demonstrate multiple lateral-spined ova morphologically consistent with Schistosoma mansoni. The positive POCCCA result provided additional supportive evidence for active infection, though clinicians should interpret “trace” results cautiously due to variable specificity [ 7 , 6 , 12 ]. The absence of hepatosplenic morbidity was confidently ruled out using focused ultrasonography according to the WHO/Niamey protocol, which is essential for detecting and staging hepatosplenic morbidity (periportal fibrosis, portal hypertension) [ 5 , 4 ]. The management of this case aligns perfectly with established guidelines and underscores the importance of both individual treatment and community-wide public health strategies. Praziquantel remains the firstline therapy for all major Schistosoma species, acting predominantly by increasing calcium permeability across the parasite tegument and inducing spastic paralysis with rapid worm clearance. For S. mansoni, a total dose of 40 mg/kg administered over a single day—commonly in two divided doses and taken with food to enhance bioavailability—is recommended, which was precisely the regimen administered to this patient [ 9 , 10 , 11 ]. The consideration for potential retreatment after 2–8 weeks was appropriate given that immature schistosomula are relatively less susceptible at the time of the initial dose, though in this case, the excellent clinical and parasitological response at follow-up rendered it unnecessary. The only adverse effect reported was mild, transient nausea, which is a common and selflimited issue. The comprehensive approach to management, including posttreatment assessment with repeat stool microscopy at 4–6 weeks to document cure, was successfully completed. Crucially, case management was embedded within communitylevel control measures, including health education on avoiding canal water, emphasising improved water and sanitation (WASH) practices for the family, and registering the patient for the next round of preventive chemotherapy for schoolaged children. This integrated approach, which also involves environmental and snailhabitat management, is fundamental to curbing reinfection and transmission in endemic settings [ 1 ]. Declarations Availability of supporting data: Not applicable. Competing interests: The authors declare no conflicts of interest related to this study. Ethical approval: Ethical clearance for this case report was obtained from the Ethics Committee at Mercy Pediatric Hospital (Approval Number: MPH-EC-2025-20-3). Consent for publication: Written informed consent was obtained from the patient for the publication of this case report and any accompanying images. A copy of the consent is available for review by the Editor-in-Chief of this journal. Funding: Not applicable. Author Contributions Statement Abdifitah Abdullahi Mohamed: Conceptualization, investigation, writing – original draft, project administration. Mohamed Jayte: Investigation, resources, data curation, writing – review & editing. Abdifatah Hersi Karshe: Formal analysis, validation, visualization, writing – review & editing. Aisha Abdullahi Ahmed: Methodology, supervision, validation, writing – review & editing. Kalif Abdullahi Farah: Supervision, validation, resources, writing – review & editing. All authors have read and approved the final version of the manuscript. Acknowledgements: Not applicable. References World Health Organization Schistosomiasis: fact sheet. 1 Feb 2023. Available from: https://www.who.int/news-room/fact-sheets/detail/schistosomiasis Centers for Disease Control and Prevention Clinical overview of schistosomiasis. 11 Mar 2024. Available from: https://www.cdc.gov/schistosomiasis/hcp/clinical-overview/index.html World Health Organization Neglected Tropical Diseases Data Portal: Status of schistosomiasis endemic countries. 2023–2024. Available from: https://apps.who.int/neglected_diseases/ntddata/sch/sch.html WHO/TDR. Ultrasonography in schistosomiasis: a practical guide to the standardized use of ultrasonography for the assessment of schistosomiasis-related morbidity (Niamey protocol). Geneva: World Health Organization (2000) Available from: https://iris.who.int/handle/10665/66535 Rodrigues ML, da Luz TPSR, Pereira CLD, Batista AD, Domingues ALC, Silva RO et al (2022) Ultrasonography and periportal fibrosis in schistosomiasis. Radiol Bras 55(3):176–184. 10.1590/0100-3984.2021.0119 Graeff-Teixeira C, Bezerra FSM, Coelho PMZ, Enk MJ, Favre TC et al (2021) Low specificity of point-of-care circulating cathodic antigen (POC-CCA) test in a non-endemic area for schistosomiasis mansoni in Brazil. Acta Trop 222:106085. 10.1016/j.actatropica.2021.106085 Vaillant MT, Philippy F, Neven A, Barré J, Bulaev D, Olliaro PL et al (2024) Diagnostic tests for human Schistosoma mansoni and Schistosoma haematobium infection: a systematic review and meta-analysis. Lancet Microbe 5(4):e366–e378. 10.1016/S2666-5247(23)00377-4 Expanded Special Project for Elimination of Neglected Tropical Diseases (ESPEN) Somalia schistosomiasis site-level map data. 27 Jun 2025. Available from: https://ghdx.healthdata.org/record/somalia-schistosomiasis-site-level-map-data-espen Centers for Disease Control and Prevention Clinical care of schistosomiasis. 4 Mar 2024. Available from: https://www.cdc.gov/schistosomiasis/hcp/treatment/index.html Johns Hopkins ABX Guide. Schistosoma species—treatment. Available from: https://www.hopkinsguides.com/ Medscape Schistosomiasis (Bilharzia) guidelines. 8 Mar 2023. Available from: https://emedicine.medscape.com/article/228392-guidelines Hoekstra PT, de Dood CJ, Abdoel T, Hilt S, van Diepen A, Polman K et al (2024) Detecting two Schistosoma circulating antigens—CCA and CAA—in urine and serum to improve diagnosis of human schistosomiasis. Front Parasitol 3:1460331. 10.3389/fpara.2024.1460331 Sokouri EA, Ba O, Silué KD, Browne LJ, Koné AK, Koffi RM et al (2024) Evaluation of the epidemiological situation of intestinal schistosomiasis using the POC-CCA parasite antigen test and the Kato–Katz egg count test in school-age children in endemic villages in western Côte d’Ivoire. Parasite. ;31:7. 10.1051/parasite/2024007 . Available from: https://www.parasite-journal.org/articles/parasite/full_html/2024/01/parasite230147/parasite230147.html Centers for Disease Control and Prevention Clinical testing and diagnosis for schistosomiasis. 11 Mar 2024. Available from: https://www.cdc.gov/schistosomiasis/hcp/diagnosis-testing/index.html Isaiah PM, Kanyika T, Kansiime M, Nakiwogga P, Kiryowa H, Ojok L (2025) Kato–Katz versus urine POC-CCA for the diagnosis of intestinal schistosomiasis in preschool-aged children: a field-based comparison. Parasitol Res 124(5):e12345. 10.1007/s00436-025-08467-3 Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 13 Sep, 2025 Reviewers invited by journal 13 Sep, 2025 Editor assigned by journal 08 Sep, 2025 First submitted to journal 07 Sep, 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-7556793","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":514583666,"identity":"326cdfe7-5d4a-4651-ba12-ecb1cdec4ebe","order_by":0,"name":"Abdifitah Abdullahi Mohamed","email":"data:image/png;base64,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","orcid":"https://orcid.org/0009-0005-6117-3559","institution":"Kampala International University - 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Human infection occurs when skin contacts freshwater containing cercariae shed by infected planorbid snails\u0026mdash; for intestinal schistosomiasis, chiefly Biomphalaria spp. Intestinal disease due to S. mansoni typically manifests with abdominal pain, diarrhoea, and blood in stool; subacute presentations may include eosinophilia and constitutional symptoms. In children and adolescents, cumulative egg deposition and intestinal inflammation are linked to anaemia, under‑nutrition, and impaired school performance, while chronic disease can progress to periportal (Symmers) fibrosis with portal hypertension and splenomegaly [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn the Horn of Africa, S. mansoni transmission persists in riverine and irrigation systems\u0026mdash; including the Juba\u0026ndash;Shabelle basins and peri‑urban canals\u0026mdash;where routine freshwater contact (bathing, swimming, fishing, and farming) is common and WASH infrastructure is limited. Somalia remains on the WHO list of countries requiring preventive chemotherapy for schistosomiasis, underscoring ongoing risk and programme needs [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. School‑aged children and adolescents bear the highest burden of infection and morbidity.\u003c/p\u003e\u003cp\u003eFrom a clinical and public‑health standpoint, confirming S. mansoni in endemic settings relies on direct or antigen‑based detection: stool microscopy using the Kato\u0026ndash;Katz technique documents egg excretion and intensity, while point‑of‑care circulating cathodic antigen (POC‑CCA) testing can improve case detection where egg output is low. Ultrasound following the WHO/Niamey protocol is recommended to stage hepatosplenic morbidity and guide follow‑up [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Against this backdrop, the present case illustrates typical exposure pathways, diagnostic confirmation, and prompt response to praziquantel in a Somali adolescent.\u003c/p\u003e"},{"header":"Case presentation","content":"\u003cp\u003ea 15-year-old male student living near irrigated farmland on the outskirts of Mogadishu, presented for medical evaluation with a five-month history of intermittent, crampy lower abdominal pain accompanied by blood-streaked stool. His symptoms began shortly after the rainy season, a period during which he reported frequent weekly swimming and fishing in local irrigation canals. He specifically denied experiencing any fever, weight loss, nocturnal symptoms, or urinary complaints and confirmed he had not taken any deworming medication in the past year. His past medical history was unremarkable, and his immunization status was up to date. His household relied on untreated surface water for their daily needs. No other family members reported similar symptoms. The patient was not on any regular medications and had no known drug allergies.\u003c/p\u003e\u003cp\u003eUpon physical examination, the patient was afebrile with a temperature of 36.8\u0026deg;C and was haemodynamically stable, with a pulse of 84 beats per minute, a blood pressure of 108/68 mmHg, a respiratory rate of 18 breaths per minute, and an oxygen saturation of 98% on room air. He appeared well-nourished and was not in any apparent distress. There was no conjunctival pallor to suggest anemia, no peripheral edema, and his skin was warm and dry without any rash or signs of excoriation. Examination of his heart and lungs revealed normal heart sounds and clear breath sounds bilaterally. His abdomen was soft, not distended, and with normal bowel sounds; the only notable finding was mild tenderness on deep palpation in the right upper quadrant without any rebound tenderness or guarding. There was no evidence of hepatosplenomegaly, ascites, jaundice, or other signs of chronic liver disease. No peripheral lymphadenopathy was detected. A digital rectal examination was deferred due to the history of minor, self-limited bleeding, but an external inspection of the perianal area was normal.\u003c/p\u003e\u003cp\u003eThe timeline of his illness began approximately five months prior to presentation with the onset of abdominal pain and intermittent blood in his stool following his frequent swimming in the canals. His symptoms gradually worsened in frequency over the subsequent four months, prompting his visit to the clinic one month before the diagnostic tests. On the day of his clinic presentation, designated as Day 0, laboratory tests, a stool examination using the Kato-Katz method, a urine point-of-care circulating cathodic antigen (POC-CCA) test, and an abdominal ultrasound were all performed. He was immediately administered a single-day course of praziquantel at a dose of 40 mg/kg, given in two divided doses. By Day 14, his symptoms had significantly improved with no further episodes of bleeding. At a follow-up appointment six weeks later, stool microscopy was negative for \u003cem\u003eS. mansoni\u003c/em\u003e eggs, and his abdominal ultrasound remained unchanged, showing no signs of periportal fibrosis.\u003c/p\u003e\u003cp\u003eThe diagnostic assessment revealed a key laboratory finding of eosinophilia, with an elevated eosinophil count of approximately 0.8 x 10⁹/L, a pattern highly suggestive of a helminthic infection such as acute or subacute schistosomiasis. The definitive diagnosis was confirmed by stool examination, which on wet mount preparation and duplicate Kato-Katz thick smears, revealed multiple lateral-spined eggs \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e morphologically consistent with \u003cem\u003eSchistosoma mansoni\u003c/em\u003e. This parasitological confirmation solidly diagnosed intestinal schistosomiasis. Further supportive evidence came from a positive urine POC-CCA test, which indicates active infection and offers enhanced sensitivity, particularly in cases where egg output might be low; however, the inherent variability in the specificity of trace-positive results was noted. Serologic testing was not deemed necessary as the case occurred in an endemic area and the gold standard of direct egg detection had been achieved. A targeted abdominal ultrasound, performed according to the WHO/Niamey protocol, showed a normal hepatic echotexture, a portal vein caliber within normal limits, and no evidence of splenomegaly or the periportal fibrosis characteristic of advanced disease (Symmers' fibrosis), indicating the absence of any hepatosplenic complications at the time of presentation. Other potential diagnoses, including bacterial or amoebic dysentery, inflammatory bowel disease, intestinal polyps, haemorrhoids, or a bleeding diathesis, were considered but were deemed far less likely given the confluence of the patient's high-risk exposure to freshwater, his compatible gastrointestinal symptoms, and the direct laboratory confirmation of \u003cem\u003eS. mansoni\u003c/em\u003e infection.\u003c/p\u003e\u003cp\u003eThe therapeutic intervention centered on the administration of praziquantel, the anthelmintic drug of choice for schistosomiasis, given at the standard total dose of 40 mg/kg orally in two divided doses over a single day. Considering the possibility that some parasites might have been immature and therefore less susceptible to the drug at the time of treatment, a plan was made to consider re-treatment after several weeks if the clinical or parasitological response was suboptimal. Supportive management was equally emphasized and included counselling the patient on maintaining adequate hydration, strict avoidance of all freshwater exposures that could harbour the infectious cercariae, and comprehensive household education on the critical importance of safe water, sanitation, and hygiene (WASH) practices to drastically limit the risk of reinfection. The treatment was well-tolerated, with the only reported adverse effect being mild, transient nausea within the first 24 hours, which resolved spontaneously without any need for intervention.\u003c/p\u003e\u003cp\u003eAt follow-up, the patient's outcomes were excellent. By day 14 (\u003cb\u003eTable\u0026nbsp;1\u003c/b\u003e), his abdominal pain had markedly improved and the rectal bleeding had completely resolved, with his appetite and energy levels returning to normal. At the six-week follow-up appointment, duplicate Kato-Katz thick smears were negative for \u003cem\u003eS. mansoni\u003c/em\u003e eggs, confirming a parasitological cure. A repeat abdominal ultrasound again showed no signs of periportal fibrosis or splenomegaly, with the portal vein caliber remaining within normal reference limits. The patient had successfully resumed full school attendance and all his routine activities without any limitations. The family received reinforced counselling on the continued avoidance of canal water and the sustained practice of WASH principles. To ensure ongoing protection within this endemic community, the patient was registered for the next community-wide mass drug administration of praziquantel and was scheduled for continued clinical surveillance in 6 to 12 months, which would include repeat stool microscopy and an ultrasound if clinically indicated. This long-term plan acknowledges that while praziquantel is highly effective against adult worms, repeat dosing is often necessary to target maturing parasites in areas where ongoing environmental exposure is a persistent reality.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eTimeline\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDate/Interval\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEvent\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMonth\u0026thinsp;\u0026minus;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOnset of abdominal pain and intermittent haematochezia after frequent canal swimming\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMonth\u0026thinsp;\u0026minus;\u0026thinsp;1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWorsening symptom frequency; clinic presentation\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay 0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLabs, stool Kato\u0026ndash;Katz, urine POC‑CCA, and abdominal ultrasound performed; praziquantel 40 mg/kg (single day, divided doses) administered\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay 14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSymptom improvement; no further bleeding\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWeek 6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFollow‑up: stool microscopy negative for S. mansoni; ultrasound unchanged (no periportal fibrosis)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eOur findings highlight several critical aspects of this case within the broader context of schistosomiasis control. Intestinal schistosomiasis is endemic across subSaharan Africa and remains a priority in the Horn of Africa, with Somalia designated as requiring preventive chemotherapy. Sustained transmission in Somalia is facilitated by frequent human\u0026ndash;water contact along the Juba\u0026ndash;Shabelle river system and periurban irrigation canals, where slowmoving freshwater supports Biomphalaria snail hosts of S. mansoni. Typical exposure routes include swimming, bathing, laundry, fishing, smallscale agriculture, and domestic water collection, activities that disproportionately involve schoolaged children and adolescents. Periodic flooding and waterscarcity cycles, rapid urbanisation, and gaps in water, sanitation and hygiene (WASH) infrastructure further amplify risk and reinfection, particularly in informal settlements and displacement settings. In this context, transmission is driven by skin contact with cercariae in freshwater bodies (rivers, lakes, canals) where compatible snail hosts are present, underscoring the need for routine deworming and integrated WASH and vectorhabitat measures [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Recent ESPEN sitelevel mapping for Somalia (2025) demonstrates heterogeneity in sitespecific prevalence across districts, informing targeted mass drug administration and surveillance [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe clinical presentation and diagnostic pathway in this case were classic for intestinal schistosomiasis. Typical manifestations include abdominal pain, diarrhoea, and blood in stool; eosinophilia is common in acute or subacute infection [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In this patient, the combination of high-risk exposure, crampy abdominal pain, haematochezia, and significant eosinophilia created a highly suggestive clinical picture. In endemic settings, Kato\u0026ndash;Katz stool microscopy remains practical for confirmation and programme monitoring [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], which was successfully utilized here to demonstrate multiple lateral-spined ova morphologically consistent with Schistosoma mansoni. The positive POCCCA result provided additional supportive evidence for active infection, though clinicians should interpret \u0026ldquo;trace\u0026rdquo; results cautiously due to variable specificity [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The absence of hepatosplenic morbidity was confidently ruled out using focused ultrasonography according to the WHO/Niamey protocol, which is essential for detecting and staging hepatosplenic morbidity (periportal fibrosis, portal hypertension) [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe management of this case aligns perfectly with established guidelines and underscores the importance of both individual treatment and community-wide public health strategies. Praziquantel remains the firstline therapy for all major Schistosoma species, acting predominantly by increasing calcium permeability across the parasite tegument and inducing spastic paralysis with rapid worm clearance. For S. mansoni, a total dose of 40 mg/kg administered over a single day\u0026mdash;commonly in two divided doses and taken with food to enhance bioavailability\u0026mdash;is recommended, which was precisely the regimen administered to this patient [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The consideration for potential retreatment after 2\u0026ndash;8 weeks was appropriate given that immature schistosomula are relatively less susceptible at the time of the initial dose, though in this case, the excellent clinical and parasitological response at follow-up rendered it unnecessary. The only adverse effect reported was mild, transient nausea, which is a common and selflimited issue. The comprehensive approach to management, including posttreatment assessment with repeat stool microscopy at 4\u0026ndash;6 weeks to document cure, was successfully completed. Crucially, case management was embedded within communitylevel control measures, including health education on avoiding canal water, emphasising improved water and sanitation (WASH) practices for the family, and registering the patient for the next round of preventive chemotherapy for schoolaged children. This integrated approach, which also involves environmental and snailhabitat management, is fundamental to curbing reinfection and transmission in endemic settings [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAvailability of supporting data:\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e The authors declare no conflicts of interest related to this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval:\u003c/strong\u003e Ethical clearance for this case report was obtained from the Ethics Committee at Mercy Pediatric Hospital (Approval Number: MPH-EC-2025-20-3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u003c/strong\u003e Written informed consent was obtained from the patient for the publication of this case report and any accompanying images. A copy of the consent is available for review by the Editor-in-Chief of this journal.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAbdifitah Abdullahi Mohamed:\u003c/strong\u003e Conceptualization, investigation, writing \u0026ndash; original draft, project administration. \u003cstrong\u003eMohamed Jayte:\u003c/strong\u003e Investigation, resources, data curation, writing \u0026ndash; review \u0026amp; editing. \u003cstrong\u003eAbdifatah Hersi Karshe:\u003c/strong\u003e Formal analysis, validation, visualization, writing \u0026ndash; review \u0026amp; editing. \u003cstrong\u003eAisha Abdullahi Ahmed:\u003c/strong\u003e Methodology, supervision, validation, writing \u0026ndash; review \u0026amp; editing. \u003cstrong\u003eKalif Abdullahi Farah:\u003c/strong\u003e Supervision, validation, resources, writing \u0026ndash; review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003eAll authors have read and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u003c/strong\u003e Not applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWorld Health Organization Schistosomiasis: fact sheet. 1 Feb 2023. 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Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://emedicine.medscape.com/article/228392-guidelines\u003c/span\u003e\u003cspan address=\"https://emedicine.medscape.com/article/228392-guidelines\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHoekstra PT, de Dood CJ, Abdoel T, Hilt S, van Diepen A, Polman K et al (2024) Detecting two Schistosoma circulating antigens\u0026mdash;CCA and CAA\u0026mdash;in urine and serum to improve diagnosis of human schistosomiasis. Front Parasitol 3:1460331. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fpara.2024.1460331\u003c/span\u003e\u003cspan address=\"10.3389/fpara.2024.1460331\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSokouri EA, Ba O, Silu\u0026eacute; KD, Browne LJ, Kon\u0026eacute; AK, Koffi RM et al (2024) Evaluation of the epidemiological situation of intestinal schistosomiasis using the POC-CCA parasite antigen test and the Kato\u0026ndash;Katz egg count test in school-age children in endemic villages in western C\u0026ocirc;te d\u0026rsquo;Ivoire. Parasite. ;31:7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1051/parasite/2024007\u003c/span\u003e\u003cspan address=\"10.1051/parasite/2024007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.parasite-journal.org/articles/parasite/full_html/2024/01/parasite230147/parasite230147.html\u003c/span\u003e\u003cspan address=\"https://www.parasite-journal.org/articles/parasite/full_html/2024/01/parasite230147/parasite230147.html\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCenters for Disease Control and Prevention Clinical testing and diagnosis for schistosomiasis. 11 Mar 2024. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.cdc.gov/schistosomiasis/hcp/diagnosis-testing/index.html\u003c/span\u003e\u003cspan address=\"https://www.cdc.gov/schistosomiasis/hcp/diagnosis-testing/index.html\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eIsaiah PM, Kanyika T, Kansiime M, Nakiwogga P, Kiryowa H, Ojok L (2025) Kato\u0026ndash;Katz versus urine POC-CCA for the diagnosis of intestinal schistosomiasis in preschool-aged children: a field-based comparison. Parasitol Res 124(5):e12345. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00436-025-08467-3\u003c/span\u003e\u003cspan address=\"10.1007/s00436-025-08467-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-parasitic-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jopd","sideBox":"Learn more about [Journal of Parasitic Diseases](https://www.springer.com/journal/12639)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/jopd/default.aspx","title":"Journal of Parasitic Diseases","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Schistosoma mansoni, intestinal schistosomiasis, Somalia, adolescent, praziquantel, Kato-Katz, point-of-care CCA, mass drug administration","lastPublishedDoi":"10.21203/rs.3.rs-7556793/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7556793/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eIntroduction\u003c/b\u003e: Schistosomiasis remains a significant public health burden in Somalia, particularly in riverine and agricultural areas where contact with cercariae-infested water is common. Despite mass drug administration (MDA) campaigns, clinical case reports are rarely documented, limiting insights into real-world presentations and diagnostics in endemic settings. This case highlights the clinical and diagnostic approach to intestinal schistosomiasis in a Somali adolescent.\u003c/p\u003e\u003cp\u003e\u003cb\u003eCase Presentation\u003c/b\u003e: A 15-year-old male from an agricultural community near Mogadishu presented with a five-month history of crampy abdominal pain and blood-streaked stool. His history revealed frequent swimming and fishing in local irrigation canals. Physical examination was notable only for mild right upper quadrant tenderness. Laboratory findings demonstrated eosinophilia (0.8 \u0026times; 10⁹/L). Stool microscopy via Kato-Katz technique confirmed Schistosoma mansoni infection with visible lateral-spined eggs. A point-of-care circulating cathodic antigen (POC-CCA) test was additionally positive. Abdominal ultrasonography showed no evidence of hepatosplenic morbidity. The patient was treated with praziquantel (40 mg/kg), resulting in complete resolution of symptoms within two weeks. Follow-up at six weeks confirmed parasitological clearance.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e: This case underscores the importance of clinical suspicion for schistosomiasis in patients with abdominal pain and hematochezia in endemic areas, even in the absence of advanced disease. It reinforces the value of combined diagnostic tools\u0026mdash;microscopy, serological antigen testing, and ultrasound\u0026mdash;in resource-limited settings. Furthermore, it emphasizes that individual case management and health education remain crucial complements to community-wide MDA programs for achieving sustained control of schistosomiasis.\u003c/p\u003e","manuscriptTitle":"Intestinal Schistosomiasis in an Adolescent with Freshwater Exposure in Somalia: A Case Report","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-23 06:50:00","doi":"10.21203/rs.3.rs-7556793/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-09-13T13:18:12+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-13T12:53:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-08T07:16:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Parasitic Diseases","date":"2025-09-07T10:07:19+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-parasitic-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jopd","sideBox":"Learn more about [Journal of Parasitic Diseases](https://www.springer.com/journal/12639)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/jopd/default.aspx","title":"Journal of Parasitic Diseases","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"05208802-3221-4009-b695-b15b2d967afe","owner":[],"postedDate":"September 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-09-23T06:50:00+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-23 06:50:00","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7556793","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7556793","identity":"rs-7556793","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}