Seroprevalence and Potential Interaction Between Bovine Leukemia Virus and Coxiella burnetii in Dairy Cattle of the United Arab Emirates

Seroprevalence and Potential Interaction Between Bovine Leukemia Virus and Coxiella burnetii in Dairy Cattle of the United Arab Emirates | 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 Seroprevalence and Potential Interaction Between Bovine Leukemia Virus and Coxiella burnetii in Dairy Cattle of the United Arab Emirates Robert BARIGYE, Nabeeha A. Hassan, Asha A. Antony, Aboma A. Zewude, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8909151/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Bovine leukemia virus (BLV) and Coxiella burnetii are important infectious pathogens of dairy cattle with potential implications for animal health, productivity, and zoonotic transmission ( C. burnetii ). Given the immunomodulatory effects of BLV, we evaluated whether BLV infection in dairy cattle was associated with increased susceptibility to C. burnetii . This cross-sectional study aimed to estimate the prevalence of BLV and C. burnetii coinfections in dairy cattle herds in the Emirate of Abu Dhabi (EAD), and to assess their association. Sera from 492 adult Holstein-Friesian cattle were screened by ELISA for antibodies to both pathogens, and associations were evaluated using logistic regression. The overall seroprevalences of BLV and C. burnetii were 47.0% and 49.4%, respectively, with 24.2% of cattle dually seropositive. BLV seroprevalences across farms were 27.6%, 56.3%, and 50.9%, while C. burnetii seroprevalences were 42.9%, 29.2%, and 53.8% for Farms 1, 2, and 3, respectively. Logistic regression showed that BLV-positive cattle had 25% higher odds of C. burnetii seropositivity (OR = 1.25, 95% CI [0.88–1.79]), even though the association was not statistically significant (p = 0.212). The relatively high seroprevalences are consistent with ongoing intra-herd transmission of both pathogens, likely exacerbated by the absence of targeted control strategies. Although no causal relationship was established, the observed trend may reflect BLV-associated immunosuppression that could enhance susceptibility to C. burnetii . Further large-scale studies are warranted, and livestock health authorities in the UAE are encouraged to implement targeted surveillance and biosecurity measures. bovine leukemia virus Coxiella burnetii dairy cattle seroprevalence United Arab Emirates 1. Introduction Enzootic bovine leukosis (EBL), caused by bovine leukemia virus (BLV), is a globally distributed and economically important disease of cattle (Moratorio et al., 2013 ; Polat et al., 2017 ). Although most BLV-infected cattle remain clinically asymptomatic, infection is associated with production losses, carcass condemnation, trade restrictions, and, in a subset of animals, fatal B-cell lymphosarcoma (Frie and Coussens, 2015 ; Kuczewski et al., 2021 ). Beyond its oncogenic potential, BLV is increasingly recognized as a modulator of immune function in cattle. Infection affects both innate and adaptive immune responses, particularly altering B- and T-lymphocyte function, cytokine signaling, and apoptosis pathways (Frie and Coussens, 2015 ; Erskine et al., 2011 ; Stone et al., 2000 ). BLV-associated immune dysregulation has been linked to impaired antibody responses and increased susceptibility to secondary infections, including mastitis, respiratory disease, and enteric infections (Frie and Coussens, 2015 ; Nakada et al., 2023 ; OIE Terrestrial Manual, 2018). These immunological alterations provide a biologically plausible basis for enhanced vulnerability to concurrent pathogens. Coxiellosis, caused by the intracellular bacterium Coxiella burnetii , is a widespread zoonosis and an important abortigenic pathogen of livestock. In cattle, infection is frequently subclinical but may result in reproductive disorders, reduced fertility, and economic loss. Moreover, C. burnetii poses a recognized public health risk, with occupational exposure documented among abattoir workers and livestock handlers. High seroprevalence of C. burnetii in ruminants has been reported across the Middle East, including in the eastern region of the Kingdom of Saudi Arabia, where cattle exhibited notable exposure in a cross-sectional survey (Aljafar et al., 2020 ) as well as in Oman, Iran, Lebanon, and Jordan (Scrimgeour et al., 2003 ; Mohabbati-Mobarez et al., 2017 ; Dabaja et al., 2020 ; Obaidat et al., 2019 ). In the United Arab Emirates (UAE), multiple studies have independently documented substantial seroprevalence of both BLV and C. burnetii in dairy cattle herds within the Emirate of Abu Dhabi (EAD) (Hassan et al., 2020 ; Barigye et al., 2020 ; Barigye et al., 2021 ; Barigye et al., 2025 ). More recently, molecular confirmation of BLV infection, including phylogenetic characterization of circulating strains, has been reported in dairy cattle from the EAD (Hassan et al., 2025 ). Similarly, PCR-based detection has confirmed active circulation of C. burnetii in regional dairy systems (Barigye et al., 2026 ; manuscript under peer review). These findings collectively demonstrate that both pathogens are not only widely prevalent serologically but are actively circulating within commercial dairy herds in the UAE. Given the confirmed presence of both pathogens and the documented immunomodulatory effects of BLV, it is biologically plausible that BLV infection may influence susceptibility to C. burnetii . Previous investigations have explored BLV coinfections with pathogens such as Neospora caninum , bovine viral diarrhoea virus (BVDV), and Mycobacterium avium subsp. paratuberculosis, with some studies reporting increased odds of secondary infections among BLV-positive cattle (Vanleeuwen et al., 2010 a-Giraldo et al., 2023; Shaukat et al., 2024 ). However, potential interactions between BLV and C. burnetii have not been evaluated in UAE dairy herds, despite the confirmed circulation of both pathogens in the region. In this context, the present cross-sectional study aimed to (i) estimate the seroprevalence of BLV and C. burnetii coinfections in commercial dairy cattle herds in the EAD, and (ii) assess the association between BLV serostatus and C. burnetii exposure. By integrating serological data within a setting of confirmed molecular circulation, this study provides updated epidemiological insight into pathogen coexistence dynamics in intensively managed dairy systems in the UAE. 2. Materials and Methods 2.1 Study area, sample size calculation and blood sample collection The entire nation of the UAE has 21 commercial dairy cattle farms distributed across four Emirates, with most located in the Emirate of Abu Dhabi (EAD) (17) (ADAFSA/Ministry of Climate Change & Environment, 2025). Of the seven Emirates, Abu Dhabi houses 41,581 dairy cattle, compared to 19,804 elsewhere nationally. This study analyzed 492 blood samples collected from three commercial dairy cattle farms in the Al Ain Region of EAD; the three study farms were subject to previous studies that evaluated the seroprevalence of the two pathogens (Hassan et al. 2020; Barigye et al. 2020; Barigye et al. 2021). A simple random sample of three out of 17 dairy cattle farms in the EAD was selected using Excel-generated random numbers, and the sample size per farm determined as described by Thrusfield (2007), assuming a 2% margin of error, a 98% confidence level, and an expected prevalence of 50%. These conservative parameters were chosen to ensure high precision and statistical power. At the time of sampling, each participating farm provided a complete list of adult cattle. However, stratified sampling by age or sex was not applied because the study population was largely homogenous, comprising only high-grade Holstein-Friesian cattle within a restricted age range (1-5-years) and reared under standardized management conditions. For these reasons, therefore, additional stratification was unlikely to meaningfully reduce bias or increase precision of seroprevalence estimates. To minimize selection bias, individual animals were randomly selected using Excel-generated numbers and blood samples were collected from the jugular vein into vacutainer tubes containing a clot activator (Weihai Sunway Medical Technology Co. Ltd, Shandong, China). For this study, a total of 492 cattle at three commercial dairy cattle farms were bled from the jugular vein and samples used to separate serum for indirect ELISA testing. Ethical approval for this research was granted by the UAEU Animal Ethics Research Committee (Certificate No. ERA_2023_2611: Molecular Studies of Bovine Leukosis in Commercial Dairy Cattle Herds from the Periurban Region of Al Ain, Abu Dhabi; approved 15 March 2023; and Certificate No. ERA_2024_4779: A One Health Study of the Animal and Public Health Significance of Q Fever at the Human–Livestock Interface in the Emirate of Abu Dhabi; approved 20 June 2024 ). All selected farms provided informed consent to participate in the study. 2.2 Enzyme-linked immunosorbent assays for the detection of antibodies against the bovine leukemia virus and Coxiella burnetii The test sera were separated from clotted cattle blood samples and, respectively, tested for antibodies against BLV and C. burnetii by using a blocking ELISA (IDEXX Laboratories, Switzerland), and indirect ELISA (Q fever Coxiella burnetii antibody test kit, IDEXX Laboratories, Switzerland) according to the manufacturers’ kit instructions. Briefly, for the BLV blocking ELISA, the test sera and the positive and negative controls were diluted at 1:2 in the kit wash buffer solution, 100 μL of diluted sera placed into the microplate wells precoated with BLV gp51 antigen. The ELISA plates were then covered and incubated at room temperature (RT) for 30 min followed by three washes using 300 μL/well of the kit wash buffer solution. Subsequently, 100 μL/ well of peroxidase-labelled anti-gp51 monoclonal antibody conjugate was added into the wells, the plates covered and then incubated at RT for 60 min. After the incubation, the plates were subjected to three washes with 300 μL/well of the kit wash buffer, and 100 μL/well of the 3,3′,5,5′-tetramethylbenzidine substrate (or TMB) added. The plates were then further incubated at RT in darkness for 20 min after which the reaction was stopped with the kit stop solution. The plates were then read at 450 nm using spectrophotometer (Multiskan Sky Thermo Scientific, Singapore), and the results calculated as a percentage of the ratio of the OD 450 of the test samples to the OD 450 value of the negative control (S/N %). Any sample that gave an S/N %< 40% was determined to be negative while one with an S/N % value ≥ 40% was considered positive for BLV antibodies. For the detection of anti- C. burnetii antibodies, the test sera as well as the positive and negative controls were diluted at 1:10 in the kit diluent solution and 100μL/well pipetted into microtiter plate wells pre-coated with inactivated C. burnetii antigen. The plates were then incubated for 60 min at 37◦C, followed by three washes with the kit wash buffer. After this step, 100 μL/well of a peroxidase labelled anti-ruminant IgG conjugate was added, and the plate incubated for another 60 min at 37◦C. Following the incubation step, the plates were washed three times as before after which 100 μL/well of the TMB substrate were added to the wells. The plates were then read using a spectrophotometer at 450 nm and the results expressed as a percentage of the ratio of the test sample OD 450 to the positive control OD 450 (S/P %). Per the kit manufacturer instructions, test samples with S/P % ≥ 40% were determined to positive and those with S/P%<40% were deemed negative for anti- C. burnetii antibodies. 2.3 Data analysis The seroprevalence of the two pathogens was expressed using proportions while the association between the two were assessed by the binary logistic regression. The R package was used for the logistic regression analysis. Farm was not included as a fixed or random effect due to limited herd numbers. Seroprevalence estimates were calculated as proportions, and 95% confidence intervals were computed using the Wilson score method. 3. Results A total of 492 adult dairy cattle from three commercial farms in the Emirate of Abu Dhabi were tested for bovine leukemia virus (BLV) and C. burnetii antibodies using ELISA. The overall seroprevalence of BLV was 47.0% (231/492; 95% CI 42.5–51.4), while that of C. burnetii was 49.4% (243/492; 95% CI 44.9–53.9). Dual seropositivity was detected in 119 animals (24.2%; 95% CI 20.4–28.3). Farm-level results are presented in Table 1. BLV seroprevalence ranged from 27.6% to 56.3% across farms, whereas C. burnetii seroprevalence ranged from 29.2% to 53.8%. Coinfection prevalence varied between 17.4% and 26.0% at the farm level. Table 1. Farm-level seroprevalence of bovine leukaemia virus and Coxiella burnetii at three study dairy cattle farms in the Al Ain Region, United Arab Emirates Farm Herd size Number of cattle tested Number BLV seropositive cattle Percentage of BLV-seropositive cattle Number of Coxiella burnetii seropositive cattle Percentage of Coxiella burnetii seropositive cattle Number /% of coinfected cattle Farm 1 1641 98 27 27.6 42 42.9 17 (17.4) Farm 2 3372 48 27 56.3 14 29.2 12 (25.0) Farm 3 15673 346 176 50.9 186 53.8 90 (26.0) Total 20686 492 231 47.0 243 49.4 119 (24.2) Footnote . Note that values expressed as percentages are rounded to one decimal place while 95% confidence intervals were calculated using the Wilson method. A binary logistic regression model was used to evaluate the association between BLV and C. burnetii serostatus (Table 2). BLV-seropositive cattle had higher odds of C. burnetii seropositivity (OR = 1.25; 95% CI 0.88–1.79), although this association was not statistically significant (p = 0.212). A summary of coinfection categories is provided in Table 3. Table 2. Logistic regression analysis of association between bovine leukaemia virus and Coxiella burnetii serostatus. Variable Estimate (β) Odds Ratio (OR) 95% CI p-value Intercept -0.13 - - 0.293 BLV-seropositive 0.23 1.25 0.88–1.79 0.212 Footnote : Note that the Odds Ratios were derived from binary logistic regression model. Table 3. Distribution of bovine leukaemia virus and Coxiella burnetii serological status. Serological status Number (n) Percentage (%) 95% CI (%) BLV+/ C. burnetii+ 119 24.2 20.4–28.3 BLV+/ C. burnetii− 112 22.8 19.2–26.8 BLV−/ C. burnetii+ 124 25.2 21.4–29.3 BLV−/ C. burnetii− 137 27.8 23.9–32.0 Footnote : Note that the percentages were calculated from total sample size (n = 492) and 95% confidence intervals calculated using Wilson score method. 4. Discussion The present study documents high seroprevalence of both BLV (47.0%) and C. burnetii (49.4%) in commercial dairy herds in the Al Ain region of the EAD in the UAE. These estimates exceed earlier regional reports (Hassan et al., 2020; Barigye et al., 2020; Barigye et al., 2021), suggesting sustained or potentially increasing pathogen circulation. In the absence of structured surveillance or targeted control programs for either BLV or C. burnetii since those initial reports, continued intra-herd transmission is biologically plausible. Herd expansion, animal movement, and limited biosecurity reinforcement may further contribute to pathogen persistence within intensively managed dairy systems. The coexistence of high seroprevalence for both pathogens, coupled with recent molecular confirmation of their active circulation in the region (Hassan et al., 2025; Barigye et al., 2026), strengthens the epidemiological relevance of evaluating potential interaction dynamics. Although logistic regression indicated that BLV-seropositive cattle had 25% higher odds of C. burnetii seropositivity (OR = 1.25), this association was not statistically significant. The wide confidence interval and non-significant p-value suggest that the observed trend may reflect limited statistical power, biological heterogeneity, or unmeasured confounding factors rather than a definitive epidemiological relationship. Nevertheless, the biological plausibility of interaction remains compelling. BLV-associated immunomodulation, particularly impairment of B- and T-cell function, could theoretically enhance susceptibility to intracellular pathogens such as C. burnetii . Similar patterns of BLV coinfection have been described with Neospora caninum , BVDV, and Mycobacterium avium subsp. paratuberculosis , where altered immune responses were hypothesized to facilitate secondary infection (Vanleeuwen et al., 2010; Rúa-Giraldo et al., 2023; Shaukat et al., 2024). In contrast, our data do not demonstrate a statistically significant association between BLV and C. burnetii serostatus, indicating that any interaction, if present, is likely modest or context-dependent. Importantly, this study provides the first serological documentation of presumed BLV– C. burnetii coinfection in dairy cattle in the UAE with coinfection in this study referring to concurrent seropositivity while not confirming simultaneous active infection. While seropositivity reflects exposure rather than active infection, the high proportion of dually seropositive animals (24.2%) underscores the epidemiological overlap of these pathogens within herds. Given that C. burnetii is associated with reproductive failure and that BLV can induce immune dysregulation, the potential impact of coinfection on reproductive performance warrants further investigation. However, reproductive outcomes could not be evaluated in the present study due to limited access to longitudinal herd health data. Overall, the findings indicate widespread exposure to both pathogens within UAE dairy systems and highlight the absence of coordinated control strategies. While a direct epidemiological link between BLV and C. burnetii was not established, the coexistence of high seroprevalence for both agents reinforces the need for integrated surveillance approaches. Future longitudinal studies incorporating molecular diagnostics, immune profiling, and reproductive performance metrics will be necessary to clarify whether BLV infection modifies susceptibility to or expression of C. burnetii infection under field conditions. 5. Conclusions This study demonstrates high seroprevalence of BLV and C. burnetii in dairy cattle herds in the EAD and documents, for the first time in the UAE, substantial serological overlap between the two pathogens. Although no statistically significant association between BLV and C. burnetii serostatus was identified, the biologically plausible role of BLV-induced immune modulation in shaping coinfection dynamics warrants further investigation. Strengthened surveillance, improved biosecurity, and coordinated control strategies are essential to reduce pathogen transmission and mitigate potential economic and public health impacts within the UAE dairy sector. Declarations Data availability statement The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Funding The research project was financially supported under SURE Plus Grant No G00003833 by the United Arab Emirates University under a research funding mechanism that promotes mentoring undergraduate students in research. Conflict of interests No potential conflicts of interest are reported by the author(s). Ethics approval statement The research project was approved by the Animal Research Ethics Committee of the United Arab Emirates University (Ref. No. ERA_2023_2611) on the 21 st of March 2023. Consent for publication Not applicable Authors' contributions Robert Barigye was project Principal Investigator who, along with co-authors Asha Antony, Ibrahim M. Abdalla-Alfaki and Gobena Ameni conceptualized and wrote the research proposal, contributed to data analysis and drafting of the manuscript. Nabeeha A. Hassan and Aboma Zewude are research assistants who did the laboratory testing of the blood samples. Co-authors Omar A.M. Alawadhi; Abdulrahman A.A. Amer; Manar S.N. Binsumaida; Maram S.S. Alshamsi; and Hamda S.H. Alderei; were undergraduate veterinary students who were mentored and participated in the laboratory testing of samples as a requirement for SURE Plus grants. Acknowledgements Special thanks go to all State veterinarians from the Abu Dhabi Agriculture and Food Safety Authority who collected the bovine blood samples. Consent for publication Not applicable References Aljafar, A., Salem, M., Housawi, F., Zaghawa, A. and Hegazy, Y. (2020) Seroprevalence and risk factors of Q fever ( Coxiella burnetii infection) among ruminants reared in the eastern region of the Kingdom of Saudi Arabia. Tropical Animal Health and Production 52, 2631–2638. https://doi.org/10.1007/s11250-020-02295-6 Barigye, R., Hassan, N.A., AlQubaisi, D.M.N. and Abdalla-Alfaki, I.M. 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Supplementary Files BLVCoxiellaDataforAnimalFarms71114.xlsx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 11 Mar, 2026 Reviewers invited by journal 24 Feb, 2026 Editor assigned by journal 22 Feb, 2026 First submitted to journal 18 Feb, 2026 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-8909151","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":596594630,"identity":"933b10bf-9254-438d-813a-f38361ad8155","order_by":0,"name":"Robert BARIGYE","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4UlEQVRIiWNgGAWjYDACCSBOAGJ+0rVINpCkBQQMDhCrw3x287MPD34dljO+kfzwMQ+DnTwD+2H8umXuHDOekdh32NjsRpqxMQ9DsmEDT1oCfndJJBgzJPYcTtx2I8FMmoeBGag8x4CAlvTPIC31m2ekf//Nw1CfwMD//gMBLTnGDAk/DicYSOSYMfMwHE5gkMjBq4NBQuZMMUNiQ7rhjDNviiXnGBw3bJN4RsBh0u2bGX/8sZbnb0/f+OFNRbU8P3/yA/zWgABjWzOUBTSfjbB6EPhTR5y6UTAKRsEoGJkAACWdQdcgs9CsAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-8420-075X","institution":"United Arab Emirates University","correspondingAuthor":true,"prefix":"","firstName":"Robert","middleName":"","lastName":"BARIGYE","suffix":""},{"id":596594631,"identity":"8ee20319-b6b2-46b5-870a-ab29e6a3eff3","order_by":1,"name":"Nabeeha A. Hassan","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Nabeeha","middleName":"A.","lastName":"Hassan","suffix":""},{"id":596594632,"identity":"8350e427-ce5d-431b-bc2a-00e6d04979be","order_by":2,"name":"Asha A. Antony","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Asha","middleName":"A.","lastName":"Antony","suffix":""},{"id":596594633,"identity":"22843cd3-c9e5-417d-a7ab-cc83202edb16","order_by":3,"name":"Aboma A. Zewude","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Aboma","middleName":"A.","lastName":"Zewude","suffix":""},{"id":596594634,"identity":"b50de9da-f273-4fa0-af10-23e131a9bcc0","order_by":4,"name":"Ibrahim A. Abdalla-Alfaki","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Ibrahim","middleName":"A.","lastName":"Abdalla-Alfaki","suffix":""},{"id":596594635,"identity":"6efd35bf-7fee-4e05-9a2c-d90026a167e4","order_by":5,"name":"Omar A.M. Alawadhi","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Omar","middleName":"A.M.","lastName":"Alawadhi","suffix":""},{"id":596594636,"identity":"31261784-cbf7-4322-9dde-5d1690be4e9c","order_by":6,"name":"Abdulrahman A.A. Amer","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Abdulrahman","middleName":"A.A.","lastName":"Amer","suffix":""},{"id":596594637,"identity":"6d87b37b-e1e8-4d6e-8183-fc0d26a6222c","order_by":7,"name":"Maram S.N. Bisumaida","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Maram","middleName":"S.N.","lastName":"Bisumaida","suffix":""},{"id":596594638,"identity":"f1b0d132-9540-4a6e-9ced-ac80dfce730d","order_by":8,"name":"Hamda S.N. Alderei","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Hamda","middleName":"S.N.","lastName":"Alderei","suffix":""},{"id":596594639,"identity":"dad707aa-2558-4340-afd7-c0e7c61bfe49","order_by":9,"name":"Gobena S.N. Ameni","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Gobena","middleName":"S.N.","lastName":"Ameni","suffix":""}],"badges":[],"createdAt":"2026-02-18 11:56:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8909151/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8909151/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103846188,"identity":"a0c9ce4f-478e-4b6d-8ea0-34e873b7b39b","added_by":"auto","created_at":"2026-03-03 15:43:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":605845,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8909151/v1/6dd247ee-3a53-4f78-afb4-2ebc00d04591.pdf"},{"id":103846187,"identity":"216da724-7967-4339-9d4c-6d2fe0d7a59d","added_by":"auto","created_at":"2026-03-03 15:43:10","extension":"xlsx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":27365,"visible":true,"origin":"","legend":"","description":"","filename":"BLVCoxiellaDataforAnimalFarms71114.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-8909151/v1/da8889c7b96a2bd333abb731.xlsx"}],"financialInterests":"","formattedTitle":"Seroprevalence and Potential Interaction Between Bovine Leukemia Virus and Coxiella burnetii in Dairy Cattle of the United Arab Emirates","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eEnzootic bovine leukosis (EBL), caused by bovine leukemia virus (BLV), is a globally distributed and economically important disease of cattle (Moratorio et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Polat et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Although most BLV-infected cattle remain clinically asymptomatic, infection is associated with production losses, carcass condemnation, trade restrictions, and, in a subset of animals, fatal B-cell lymphosarcoma (Frie and Coussens, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Kuczewski et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Beyond its oncogenic potential, BLV is increasingly recognized as a modulator of immune function in cattle. Infection affects both innate and adaptive immune responses, particularly altering B- and T-lymphocyte function, cytokine signaling, and apoptosis pathways (Frie and Coussens, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Erskine et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Stone et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). BLV-associated immune dysregulation has been linked to impaired antibody responses and increased susceptibility to secondary infections, including mastitis, respiratory disease, and enteric infections (Frie and Coussens, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Nakada et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; OIE Terrestrial Manual, 2018). These immunological alterations provide a biologically plausible basis for enhanced vulnerability to concurrent pathogens.\u003c/p\u003e \u003cp\u003eCoxiellosis, caused by the intracellular bacterium \u003cem\u003eCoxiella burnetii\u003c/em\u003e, is a widespread zoonosis and an important abortigenic pathogen of livestock. In cattle, infection is frequently subclinical but may result in reproductive disorders, reduced fertility, and economic loss. Moreover, \u003cem\u003eC. burnetii\u003c/em\u003e poses a recognized public health risk, with occupational exposure documented among abattoir workers and livestock handlers. High seroprevalence of \u003cem\u003eC. burnetii\u003c/em\u003e in ruminants has been reported across the Middle East, including in the eastern region of the Kingdom of Saudi Arabia, where cattle exhibited notable exposure in a cross-sectional survey (Aljafar et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) as well as in Oman, Iran, Lebanon, and Jordan (Scrimgeour et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Mohabbati-Mobarez et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Dabaja et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Obaidat et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the United Arab Emirates (UAE), multiple studies have independently documented substantial seroprevalence of both BLV and \u003cem\u003eC. burnetii\u003c/em\u003e in dairy cattle herds within the Emirate of Abu Dhabi (EAD) (Hassan et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Barigye et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Barigye et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Barigye et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). More recently, molecular confirmation of BLV infection, including phylogenetic characterization of circulating strains, has been reported in dairy cattle from the EAD (Hassan et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Similarly, PCR-based detection has confirmed active circulation of \u003cem\u003eC. burnetii\u003c/em\u003e in regional dairy systems (Barigye et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2026\u003c/span\u003e; manuscript under peer review). These findings collectively demonstrate that both pathogens are not only widely prevalent serologically but are actively circulating within commercial dairy herds in the UAE.\u003c/p\u003e \u003cp\u003eGiven the confirmed presence of both pathogens and the documented immunomodulatory effects of BLV, it is biologically plausible that BLV infection may influence susceptibility to \u003cem\u003eC. burnetii\u003c/em\u003e. Previous investigations have explored BLV coinfections with pathogens such as \u003cem\u003eNeospora caninum\u003c/em\u003e, bovine viral diarrhoea virus (BVDV), and Mycobacterium avium subsp. paratuberculosis, with some studies reporting increased odds of secondary infections among BLV-positive cattle (Vanleeuwen et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2010\u003c/span\u003ea-Giraldo et al., 2023; Shaukat et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). However, potential interactions between BLV and \u003cem\u003eC. burnetii\u003c/em\u003e have not been evaluated in UAE dairy herds, despite the confirmed circulation of both pathogens in the region.\u003c/p\u003e \u003cp\u003eIn this context, the present cross-sectional study aimed to (i) estimate the seroprevalence of BLV and \u003cem\u003eC. burnetii\u003c/em\u003e coinfections in commercial dairy cattle herds in the EAD, and (ii) assess the association between BLV serostatus and \u003cem\u003eC. burnetii\u003c/em\u003e exposure. By integrating serological data within a setting of confirmed molecular circulation, this study provides updated epidemiological insight into pathogen coexistence dynamics in intensively managed dairy systems in the UAE.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cp\u003e\u003cstrong\u003e2.1 Study area, sample size calculation and blood sample collection\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The entire nation of the UAE has 21 commercial dairy cattle farms distributed across four Emirates, with most located in the Emirate of Abu Dhabi (EAD) (17) (ADAFSA/Ministry of Climate Change \u0026amp; Environment, 2025). Of the seven Emirates, Abu Dhabi houses 41,581 dairy cattle, compared to 19,804 elsewhere nationally. This study analyzed 492 blood samples collected from three commercial dairy cattle farms in the Al Ain Region of EAD; the three study farms were subject to previous studies that evaluated the seroprevalence of the two pathogens (Hassan et al. 2020; Barigye et al. 2020; Barigye et al. 2021). A simple random sample of three out of 17 dairy cattle farms in the EAD was selected using Excel-generated random numbers, and the sample size per farm determined as described by Thrusfield (2007), assuming a 2% margin of error, a 98% confidence level, and an expected prevalence of 50%. These conservative parameters were chosen to ensure high precision and statistical power. At the time of sampling, each participating farm provided a complete list of adult cattle. However, stratified sampling by age or sex was not applied because the study population was largely homogenous, comprising only high-grade Holstein-Friesian cattle within a restricted age range (1-5-years) and reared under standardized management conditions. For these reasons, therefore, additional stratification was unlikely to meaningfully reduce bias or increase precision of seroprevalence estimates. To minimize selection bias, individual animals were randomly selected using Excel-generated numbers and blood samples were collected from the jugular vein into vacutainer tubes containing a clot activator (Weihai Sunway Medical Technology Co. Ltd, Shandong, China). For this study, a total of 492 cattle at three commercial dairy cattle farms were bled from the jugular vein and samples used to separate serum for indirect ELISA testing. Ethical approval for this research was granted by the UAEU Animal Ethics Research Committee (Certificate No. ERA_2023_2611: \u003cem\u003eMolecular Studies of Bovine Leukosis in Commercial Dairy Cattle Herds from the Periurban Region of Al Ain, Abu Dhabi; approved 15 March 2023; and\u003c/em\u003e Certificate No. ERA_2024_4779: \u003cem\u003eA One Health Study of the Animal and Public Health Significance of Q Fever at the Human\u0026ndash;Livestock Interface in the Emirate of Abu Dhabi; approved 20 June 2024\u003c/em\u003e). All selected farms provided informed consent to participate in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Enzyme-linked immunosorbent assays for the detection of antibodies against the bovine leukemia virus and \u003cem\u003eCoxiella burnetii\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe test sera were separated from clotted cattle blood samples and, respectively, tested for antibodies against BLV and \u003cem\u003eC. burnetii\u003c/em\u003e by using a blocking ELISA (IDEXX Laboratories, Switzerland), and indirect ELISA (Q fever \u003cem\u003eCoxiella burnetii\u003c/em\u003e antibody test kit, IDEXX Laboratories, Switzerland) according to the manufacturers\u0026rsquo; kit instructions. Briefly, for the BLV blocking ELISA, the test sera and the positive and negative controls were diluted at 1:2 in the kit wash buffer solution, 100 \u0026mu;L of diluted sera placed into the microplate wells precoated with BLV gp51 antigen. The ELISA plates were then covered and incubated at room temperature (RT) for 30 min followed by three washes using 300 \u0026mu;L/well of the kit wash buffer solution. Subsequently, 100 \u0026mu;L/ well of peroxidase-labelled anti-gp51 monoclonal antibody conjugate was added into the wells, the plates covered and then incubated at RT for 60 min. After the incubation, the plates were subjected to three washes with 300 \u0026mu;L/well of the kit wash buffer, and 100 \u0026mu;L/well of the 3,3\u0026prime;,5,5\u0026prime;-tetramethylbenzidine substrate (or TMB) added. The plates were then further incubated at RT in darkness for 20 min after which the reaction was stopped with the kit stop solution. The plates were then read at 450 nm using spectrophotometer (Multiskan Sky Thermo Scientific, Singapore), and the results calculated as a percentage of the ratio of the OD\u003csub\u003e450\u003c/sub\u003e of the test samples to the OD\u003csub\u003e450\u003c/sub\u003e value of the negative control (S/N %). Any sample that gave an S/N %\u0026lt; 40% was determined to be negative while one with an S/N % value \u0026ge; 40% was considered positive for BLV antibodies. For the detection of anti-\u003cem\u003eC. burnetii\u003c/em\u003e antibodies, the test sera as well as the positive and negative controls were diluted at 1:10 in the kit diluent solution and 100\u0026mu;L/well pipetted into microtiter plate wells pre-coated with inactivated \u003cem\u003eC. burnetii\u0026nbsp;\u003c/em\u003eantigen. The plates were then incubated for 60 min at 37◦C, followed by three washes with the kit wash buffer. After this step, 100 \u0026mu;L/well of a peroxidase labelled anti-ruminant IgG conjugate was added, and the plate incubated for another 60 min at 37◦C. Following the incubation step, the plates were washed three times as before after which 100 \u0026mu;L/well of the TMB substrate were added to the wells. The plates were then read using a spectrophotometer at 450 nm and the results expressed as a percentage of the ratio of the test sample OD\u003csub\u003e450\u003c/sub\u003e to the positive control OD\u003csub\u003e450\u003c/sub\u003e (S/P %). Per the kit manufacturer instructions, test samples with S/P % \u0026ge; 40% were determined to positive and those with S/P%\u0026lt;40% were deemed negative for anti-\u003cem\u003eC. burnetii\u003c/em\u003e antibodies.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Data analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe seroprevalence of the two pathogens was expressed using proportions while the association between the two were assessed by the binary logistic regression. \u0026nbsp;The R package was used for the logistic regression analysis. \u0026nbsp; Farm was not included as a fixed or random effect due to limited herd numbers. Seroprevalence estimates were calculated as proportions, and 95% confidence intervals were computed using the Wilson score method.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003eA total of 492 adult dairy cattle from three commercial farms in the Emirate of Abu Dhabi were tested for bovine leukemia virus (BLV) and \u003cem\u003eC. burnetii\u003c/em\u003e antibodies using ELISA. The overall seroprevalence of BLV was 47.0% (231/492; 95% CI 42.5\u0026ndash;51.4), while that of \u003cem\u003eC. burnetii\u003c/em\u003e was 49.4% (243/492; 95% CI 44.9\u0026ndash;53.9). Dual seropositivity was detected in 119 animals (24.2%; 95% CI 20.4\u0026ndash;28.3). Farm-level results are presented in Table 1.\u003c/p\u003e\n\u003cp\u003eBLV seroprevalence ranged from 27.6% to 56.3% across farms, whereas \u003cem\u003eC. burnetii\u003c/em\u003e seroprevalence ranged from 29.2% to 53.8%. Coinfection prevalence varied between 17.4% and 26.0% at the farm level.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1.\u0026nbsp;\u003c/strong\u003eFarm-level seroprevalence of bovine leukaemia virus and \u003cem\u003eCoxiella burnetii\u003c/em\u003e at three study dairy cattle farms in the Al Ain Region, United Arab Emirates\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eFarm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eHerd size\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eNumber of cattle tested\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003eNumber BLV seropositive cattle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003ePercentage of BLV-seropositive cattle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003eNumber of\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u003cem\u003eCoxiella burnetii\u003c/em\u003e seropositive cattle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003ePercentage of \u003cem\u003eCoxiella burnetii\u003c/em\u003e seropositive cattle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eNumber /% of coinfected cattle\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eFarm 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e1641\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003e27.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e42.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e17 (17.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eFarm 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e3372\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003e56.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e29.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e12 (25.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eFarm 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e15673\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e346\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003e176\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003e50.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e186\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e53.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e90 (26.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e20686\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e492\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003e231\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 92px;\"\u003e\n \u003cp\u003e47.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e243\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e49.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e119 (24.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eFootnote\u003c/strong\u003e. Note that values expressed as percentages are rounded to one decimal place while 95% confidence intervals were calculated using the Wilson method.\u003c/p\u003e\n\u003cp\u003eA binary logistic regression model was used to evaluate the association between BLV and \u003cem\u003eC. burnetii\u003c/em\u003e serostatus (Table 2). BLV-seropositive cattle had higher odds of \u003cem\u003eC. burnetii\u003c/em\u003e seropositivity (OR = 1.25; 95% CI 0.88\u0026ndash;1.79), although this association was not statistically significant (p = 0.212). A summary of coinfection categories is provided in Table 3.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e Logistic regression analysis of association between bovine leukaemia virus and \u003cem\u003eCoxiella burnetii\u003c/em\u003e serostatus.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003eEstimate (\u0026beta;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eOdds Ratio (OR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eIntercept\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e-0.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.293\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eBLV-seropositive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e1.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e0.88\u0026ndash;1.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.212\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eFootnote\u003c/strong\u003e: Note that the Odds Ratios were derived from binary logistic regression model.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3.\u003c/strong\u003e Distribution of bovine leukaemia virus and \u003cem\u003eCoxiella burnetii\u003c/em\u003e serological status.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eSerological status\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eNumber (n)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003ePercentage (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e95% CI (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eBLV+/\u003cem\u003eC. burnetii+\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e119\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e24.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e20.4\u0026ndash;28.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eBLV+/\u003cem\u003eC. burnetii\u0026minus;\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e22.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e19.2\u0026ndash;26.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eBLV\u0026minus;/\u003cem\u003eC. burnetii+\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e124\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e25.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e21.4\u0026ndash;29.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eBLV\u0026minus;/\u003cem\u003eC. burnetii\u0026minus;\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e137\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e27.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e23.9\u0026ndash;32.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eFootnote\u003c/strong\u003e: Note that the percentages were calculated from total sample size (n = 492) and 95% confidence intervals calculated using Wilson score method.\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThe present study documents high seroprevalence of both BLV (47.0%) and \u003cem\u003eC. burnetii\u003c/em\u003e (49.4%) in commercial dairy herds in the Al Ain region of the EAD in the UAE. These estimates exceed earlier regional reports (Hassan et al., 2020; Barigye et al., 2020; Barigye et al., 2021), suggesting sustained or potentially increasing pathogen circulation. In the absence of structured surveillance or targeted control programs for either BLV or \u003cem\u003eC. burnetii\u003c/em\u003e since those initial reports, continued intra-herd transmission is biologically plausible. Herd expansion, animal movement, and limited biosecurity reinforcement may further contribute to pathogen persistence within intensively managed dairy systems.\u003c/p\u003e\n\u003cp\u003eThe coexistence of high seroprevalence for both pathogens, coupled with recent molecular confirmation of their active circulation in the region (Hassan et al., 2025; Barigye et al., 2026), strengthens the epidemiological relevance of evaluating potential interaction dynamics. Although logistic regression indicated that BLV-seropositive cattle had 25% higher odds of \u003cem\u003eC. burnetii\u003c/em\u003e seropositivity (OR = 1.25), this association was not statistically significant. The wide confidence interval and non-significant p-value suggest that the observed trend may reflect limited statistical power, biological heterogeneity, or unmeasured confounding factors rather than a definitive epidemiological relationship. Nevertheless, the biological plausibility of interaction remains compelling. BLV-associated immunomodulation, particularly impairment of B- and T-cell function, could theoretically enhance susceptibility to intracellular pathogens such as \u003cem\u003eC. burnetii\u003c/em\u003e. Similar patterns of BLV coinfection have been described with \u003cem\u003eNeospora caninum\u003c/em\u003e, BVDV, and \u003cem\u003eMycobacterium avium\u003c/em\u003e subsp. \u003cem\u003eparatuberculosis\u003c/em\u003e, where altered immune responses were hypothesized to facilitate secondary infection (Vanleeuwen et al., 2010; R\u0026uacute;a-Giraldo et al., 2023; Shaukat et al., 2024). In contrast, our data do not demonstrate a statistically significant association between BLV and \u003cem\u003eC. burnetii\u003c/em\u003e serostatus, indicating that any interaction, if present, is likely modest or context-dependent.\u003c/p\u003e\n\u003cp\u003eImportantly, this study provides the first serological documentation of presumed BLV\u0026ndash;\u003cem\u003eC. burnetii\u003c/em\u003e coinfection in dairy cattle in the UAE with coinfection in this study referring to concurrent seropositivity while not confirming simultaneous active infection. While seropositivity reflects exposure rather than active infection, the high proportion of dually seropositive animals (24.2%) underscores the epidemiological overlap of these pathogens within herds. Given that \u003cem\u003eC. burnetii\u003c/em\u003e is associated with reproductive failure and that BLV can induce immune dysregulation, the potential impact of coinfection on reproductive performance warrants further investigation. However, reproductive outcomes could not be evaluated in the present study due to limited access to longitudinal herd health data.\u003c/p\u003e\n\u003cp\u003eOverall, the findings indicate widespread exposure to both pathogens within UAE dairy systems and highlight the absence of coordinated control strategies. While a direct epidemiological link between BLV and \u003cem\u003eC. burnetii\u003c/em\u003e was not established, the coexistence of high seroprevalence for both agents reinforces the need for integrated surveillance approaches. Future longitudinal studies incorporating molecular diagnostics, immune profiling, and reproductive performance metrics will be necessary to clarify whether BLV infection modifies susceptibility to or expression of \u003cem\u003eC. burnetii\u003c/em\u003e infection under field conditions.\u003c/p\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eThis study demonstrates high seroprevalence of BLV and \u003cem\u003eC. burnetii\u003c/em\u003e in dairy cattle herds in the EAD and documents, for the first time in the UAE, substantial serological overlap between the two pathogens. Although no statistically significant association between BLV and \u003cem\u003eC. burnetii\u003c/em\u003e serostatus was identified, the biologically plausible role of BLV-induced immune modulation in shaping coinfection dynamics warrants further investigation. Strengthened surveillance, improved biosecurity, and coordinated control strategies are essential to reduce pathogen transmission and mitigate potential economic and public health impacts within the UAE dairy sector.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe research project was financially supported under SURE Plus Grant No G00003833 by the United Arab Emirates University under a research funding mechanism that promotes mentoring undergraduate students in research.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo potential conflicts of interest are reported by the author(s).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe research project was approved by the Animal Research Ethics Committee of the United Arab Emirates University (Ref. No. ERA_2023_2611) on the 21\u003csup\u003est\u003c/sup\u003e of March 2023.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRobert Barigye was project Principal Investigator who, along with co-authors Asha Antony, Ibrahim M. Abdalla-Alfaki and Gobena Ameni conceptualized and wrote the research proposal, contributed to data analysis and drafting of the manuscript. Nabeeha A. Hassan and Aboma Zewude are research assistants who did the laboratory testing of the blood samples. Co-authors Omar A.M. Alawadhi; Abdulrahman A.A. Amer; Manar S.N. Binsumaida; Maram S.S. Alshamsi; and Hamda S.H. Alderei; were undergraduate veterinary students who were mentored and participated in the laboratory testing of samples as a requirement for SURE Plus grants.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSpecial thanks go to all State veterinarians from the Abu Dhabi Agriculture and Food Safety Authority who collected the bovine blood samples.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAljafar, A., Salem, M., Housawi, F., Zaghawa, A. and Hegazy, Y. (2020) Seroprevalence and risk factors of Q fever (\u003cem\u003eCoxiella burnetii\u003c/em\u003e infection) among ruminants reared in the eastern region of the Kingdom of Saudi Arabia. Tropical Animal Health and Production 52, 2631\u0026ndash;2638. https://doi.org/10.1007/s11250-020-02295-6\u003c/li\u003e\n \u003cli\u003eBarigye, R., Hassan, N.A., AlQubaisi, D.M.N. and Abdalla-Alfaki, I.M. (2020) Serological evidence of \u003cem\u003eCoxiella burnetii, Leptospira interrogans Hardjo, Neospora caninum\u003c/em\u003e and bovine pestivirus infections in a dairy cattle herd from the United Arab Emirates. Veterinaria Italiana 56, 163\u0026ndash;168. https://doi.org/10.12834/VetIt.2257.12932.1\u003c/li\u003e\n \u003cli\u003eBarigye, R., Hassan, N.A.D., Abdalla Alfaki, I.M., Barongo, M.B., Mohamed, M.E.H. and Mohteshamuddin, K. (2021) Seroprevalence of \u003cem\u003eCoxiella burnetii\u003c/em\u003e in a dairy cattle herd from the Al Ain region, United Arab Emirates. 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PLoS Neglected Tropical Diseases 11, e0005521. https://doi.org/10.1371/journal.pntd.0005521\u003c/li\u003e\n \u003cli\u003eMoratorio, G., Fischer, S., Bianchi, S., Tom\u0026eacute;, L. and Rama, G. (2013) A detailed molecular analysis of complete bovine leukemia virus genomes isolated from B-cell lymphosarcomas. Veterinary Research 44, 19. https://doi.org/10.1186/1297-9716-44-19\u003c/li\u003e\n \u003cli\u003eNakada, S., Fujimoto, Y., Kohara, J. and Makita, K. (2023) Economic losses associated with mastitis due to bovine leukemia virus infection. Journal of Dairy Science 106, 576\u0026ndash;588. https://doi.org/10.3168/jds.2021-21722\u003c/li\u003e\n \u003cli\u003eObaidat, M.M., Malania, L. and Imnadze, P. (2019) Seroprevalence and risk factors for \u003cem\u003eCoxiella burnetii\u003c/em\u003e in Jordan. American Journal of Tropical Medicine and Hygiene 101, 40\u0026ndash;44. https://doi.org/10.4269/ajtmh.19-0049\u003c/li\u003e\n \u003cli\u003ePolat, M., Takeshima, S.N. and Aida, Y. 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In: Manual of Diagnostic Tests and Vaccines for Terrestrial Animals.\u003c/li\u003e\n\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":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"tropical-animal-health-and-production","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trop","sideBox":"Learn more about [Tropical Animal Health and Production](https://www.springer.com/journal/11250)","snPcode":"11250","submissionUrl":"https://submission.nature.com/new-submission/11250/3","title":"Tropical Animal Health and Production","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"bovine leukemia virus, Coxiella burnetii, dairy cattle, seroprevalence, United Arab Emirates","lastPublishedDoi":"10.21203/rs.3.rs-8909151/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8909151/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBovine leukemia virus (BLV) and \u003cem\u003eCoxiella burnetii\u003c/em\u003e are important infectious pathogens of dairy cattle with potential implications for animal health, productivity, and zoonotic transmission (\u003cem\u003eC. burnetii\u003c/em\u003e). Given the immunomodulatory effects of BLV, we evaluated whether BLV infection in dairy cattle was associated with increased susceptibility to \u003cem\u003eC. burnetii\u003c/em\u003e. This cross-sectional study aimed to estimate the prevalence of BLV and \u003cem\u003eC. burnetii\u003c/em\u003e coinfections in dairy cattle herds in the Emirate of Abu Dhabi (EAD), and to assess their association. Sera from 492 adult Holstein-Friesian cattle were screened by ELISA for antibodies to both pathogens, and associations were evaluated using logistic regression. The overall seroprevalences of BLV and \u003cem\u003eC. burnetii\u003c/em\u003e were 47.0% and 49.4%, respectively, with 24.2% of cattle dually seropositive. BLV seroprevalences across farms were 27.6%, 56.3%, and 50.9%, while \u003cem\u003eC. burnetii\u003c/em\u003e seroprevalences were 42.9%, 29.2%, and 53.8% for Farms 1, 2, and 3, respectively. Logistic regression showed that BLV-positive cattle had 25% higher odds of \u003cem\u003eC. burnetii\u003c/em\u003e seropositivity (OR\u0026thinsp;=\u0026thinsp;1.25, 95% CI [0.88\u0026ndash;1.79]), even though the association was not statistically significant (p\u0026thinsp;=\u0026thinsp;0.212). The relatively high seroprevalences are consistent with ongoing intra-herd transmission of both pathogens, likely exacerbated by the absence of targeted control strategies. Although no causal relationship was established, the observed trend may reflect BLV-associated immunosuppression that could enhance susceptibility to \u003cem\u003eC. burnetii\u003c/em\u003e. Further large-scale studies are warranted, and livestock health authorities in the UAE are encouraged to implement targeted surveillance and biosecurity measures.\u003c/p\u003e","manuscriptTitle":"Seroprevalence and Potential Interaction Between Bovine Leukemia Virus and Coxiella burnetii in Dairy Cattle of the United Arab Emirates","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-03 15:43:05","doi":"10.21203/rs.3.rs-8909151/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2026-03-11T17:53:20+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-25T01:36:15+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-23T02:34:35+00:00","index":"","fulltext":""},{"type":"submitted","content":"Tropical Animal Health and Production","date":"2026-02-19T04:01:59+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"tropical-animal-health-and-production","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trop","sideBox":"Learn more about [Tropical Animal Health and Production](https://www.springer.com/journal/11250)","snPcode":"11250","submissionUrl":"https://submission.nature.com/new-submission/11250/3","title":"Tropical Animal Health and Production","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"3e66a125-a93f-4a50-b1f4-a9aba02e9b39","owner":[],"postedDate":"March 3rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-13T19:48:58+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-03 15:43:05","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8909151","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8909151","identity":"rs-8909151","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}