{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T22:11:14Z","timestamp":1790892674969,"version":"4.1.0"},"reference-count":46,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2025,7,16]],"date-time":"2025-07-16T00:00:00Z","timestamp":1752624000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100017170","name":"Innovation and Ministry of Education (2025 Higher Education Sprout Project (Part II) Special Areas Research Center Program (Taiwan)","doi-asserted-by":"publisher","award":["RGNS 65-091"],"award-info":[{"award-number":["RGNS 65-091"]}],"id":[{"id":"10.13039\/501100017170","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100017170","name":"Innovation and Ministry of Education (2025 Higher Education Sprout Project (Part II) Special Areas Research Center Program (Taiwan)","doi-asserted-by":"publisher","award":["RGNS 65-091"],"award-info":[{"award-number":["RGNS 65-091"]}],"id":[{"id":"10.13039\/501100017170","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100017170","name":"Thailand Science Research","doi-asserted-by":"publisher","award":["RGNS 65-091"],"award-info":[{"award-number":["RGNS 65-091"]}],"id":[{"id":"10.13039\/501100017170","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100017170","name":"Thailand Science Research","doi-asserted-by":"publisher","award":["RGNS 65-091"],"award-info":[{"award-number":["RGNS 65-091"]}],"id":[{"id":"10.13039\/501100017170","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>Chicken anemia virus (CAV) and Eimeria tenella (E. tenella) are economically important pathogens of the poultry industry worldwide. However, the impact of dual infection of these two pathogens in chickens remains unclear. This study investigated the pathogenic effects of dual infection with CAV and E. tenella using two trials. In Trial A, chickens were infected at 21 days of age (D21) with either CAV and E. tenella simultaneously (C21 + T21), CAV alone (C21a), E. tenella alone (T21), or PBS as a negative control (NC). In Trial B, chickens received CAV at D21 followed by E. tenella at D28 (C21 + T28), CAV alone at D21 (C21b), E. tenella alone at D28 (T28), or PBS at D21 (NC). Assays of lesion scores (LS), oocysts per gram (OPG) of feces, packed cell volume (PCV), and thymus index (TI) were used to assess variations in pathogenicity. Both the C21 + T21 and C21 + T28 groups showed higher OPG than the group infected with E. tenella alone, with significantly elevated OPG in the secondary infection scenario and more severe lesions in the concurrent co-infection group (p &lt; 0.05). Anemia, indicated by PCV &lt; 27%, was observed in the C21 + T21 group at day 28 and in the C21 + T28 group at day 35, both of which had significantly lower PCV values than the group infected with CAV alone (p &lt; 0.001). Thymus atrophy was most severe in C21 + T21 at 28 days old (p &lt; 0.05; p &lt; 0.01). In this study, preliminary observations suggested that concurrent and secondary infections with CAV and E. tenella showed variable trends that may indicate potential interactions; however, these exploratory findings require more systematic validation in older chickens.<\/jats:p>","DOI":"10.3390\/microorganisms13071676","type":"journal-article","created":{"date-parts":[[2025,7,16]],"date-time":"2025-07-16T15:48:22Z","timestamp":1752680902000},"page":"1676","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Pathogenicity in Chicken Anemia Virus with Eimeria tenella: Concurrent Co-Infection and Secondary Eimeria tenella Infection"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0009-0003-4139-7577","authenticated-orcid":false,"given":"Hsyang-Hsun","family":"Chung","sequence":"first","affiliation":[{"name":"Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-4935-644X","authenticated-orcid":false,"given":"Suttitas","family":"Tongkamsai","sequence":"additional","affiliation":[{"name":"Faculty of Veterinary Medicine, Rajamangala University of Technology Tawan-ok, Chonburi 20110, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ming-Chu","family":"Cheng","sequence":"additional","affiliation":[{"name":"Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan"},{"name":"Research Center of Animal Biologics, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9203-7585","authenticated-orcid":false,"given":"Yi-Lun","family":"Tsai","sequence":"additional","affiliation":[{"name":"Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Meng-Shiou","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, College of Chinese Medicine, China Medical University, 91 Hsueh-Shih Road, Taichung 40402, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yi-Yang","family":"Lien","sequence":"additional","affiliation":[{"name":"Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan"},{"name":"Research Center of Animal Biologics, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ya-Mei","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan"},{"name":"Research Center of Animal Biologics, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"366","DOI":"10.2307\/1589567","article-title":"Isolation and some characteristics of an agent inducing anemia in chicks","volume":"17","author":"Yuasa","year":"1979","journal-title":"Avian Dis."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"366","DOI":"10.2307\/1591660","article-title":"Effects of chicken anemia virus on cell-mediated immune function in chickens exposed to the virus by a natural route","volume":"37","author":"McConnell","year":"1993","journal-title":"Avian Dis."},{"key":"ref_3","unstructured":"Santen, V.L., and Schat, K.A. (2020). Chicken Infectious Anemia and Circovirus Infections in Commercial Flocks. Diseases of Poultry, John Wiley & Sons. [14th ed.]."},{"key":"ref_4","first-page":"302","article-title":"The anti-nuclease humoral immune response of broiler chickens exposed to Staphylococcus aureus, infectious bursal disease virus and chicken anaemia virus in an experimental model for bacterial chondronecrosis and osteomyelitis","volume":"35","author":"Rodgers","year":"2006","journal-title":"Avian Dis."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"739","DOI":"10.56093\/ijans.v94i9.144412","article-title":"Pathological studies on chicken infectious anaemia and concurrent infections in layer flocks of Namakkal, Tamil Nadu","volume":"94","author":"Suohu","year":"2024","journal-title":"Indian J. Anim. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1637\/8909-043009-Review.1","article-title":"Clinical aspects of immunosuppression in poultry","volume":"54","author":"Hoerr","year":"2010","journal-title":"Avian Dis."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"422","DOI":"10.1292\/jvms.20-0006","article-title":"Pathological and virological analysis of concurrent disease of chicken anemia virus infection and infectious bronchitis in Japanese native chicks","volume":"82","author":"Hosokawa","year":"2020","journal-title":"J. Vet. Med. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1637\/8408-071408-Reg.1","article-title":"Effects of chicken anemia virus and infectious bursal disease virus in commercial chickens","volume":"53","author":"Toro","year":"2009","journal-title":"Avian Dis."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"469","DOI":"10.1080\/03079450903349162","article-title":"Pathological and immunohistochemical study of chickens with co-infection of Marek\u2019s disease virus and chicken anaemia virus","volume":"38","author":"Haridy","year":"2009","journal-title":"Avian Pathol."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Xu, H., Li, W., Nie, Y., Chen, S., Li, H., Zhang, X., Xie, Q., and Chen, W. (2024). Synergy of subgroup J avian leukosis virus and chicken infectious anemia virus enhances the pathogenicity in chickens. Microorganisms, 12.","DOI":"10.3390\/microorganisms12040740"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Liu, L., Gao, W., Chang, J., Liu, J., Huang, Z., Sun, W., Song, Y., and Li, X. (2025). Co-Infection of Chicken Infectious Anemia Virus and Fowl Adenovirus Serotype E8b Increases Mortality in Chickens. Viruses, 17.","DOI":"10.3390\/v17050620"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"McNeilly, F., Smyth, J., Adair, B., and McNulty, M. (1995). Synergism between chicken anemia virus (CAV) and avian reovirus following dual infection of 1-day-old chicks by a natural route. Avian Dis., 532\u2013537.","DOI":"10.2307\/1591806"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1007\/s11250-022-03097-8","article-title":"Molecular and pathological characterization of natural co-infection of poultry farms with the recently emerged Leucocytozoon caulleryi and chicken anemia virus in Egypt","volume":"54","author":"Hamed","year":"2022","journal-title":"Trop. Anim. Health Prod."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1777","DOI":"10.1017\/S0031182013001170","article-title":"Interactions of Plasmodium juxtanucleare and chicken anaemia virus: Establishing a model","volume":"140","author":"Silveira","year":"2013","journal-title":"Parasitology"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1016\/S0304-4017(97)00046-0","article-title":"Interaction of chicken anaemia virus and Cryptosporidium baileyi in experimentally infected chickens","volume":"76","author":"Hornok","year":"1998","journal-title":"Vet. Parasitol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1186\/s13567-020-00837-2","article-title":"Re-calculating the cost of coccidiosis in chickens","volume":"51","author":"Blake","year":"2020","journal-title":"Vet. Res."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1016\/j.vetpar.2007.12.028","article-title":"Genetic characterization of three unique operational taxonomic units of Eimeria from chickens in Australia based on nuclear spacer ribosomal DNA","volume":"152","author":"Cantacessi","year":"2008","journal-title":"Vet. Parasitol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"621","DOI":"10.1016\/j.ijpara.2020.12.004","article-title":"Genetic and biological characterisation of three cryptic Eimeria operational taxonomic units that infect chickens (Gallus gallus domesticus)","volume":"51","author":"Blake","year":"2021","journal-title":"Int. J. Parasitol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1128\/IAI.00772-18","article-title":"Impact of Eimeria tenella coinfection on Campylobacter jejuni colonization of the chicken","volume":"87","author":"Macdonald","year":"2019","journal-title":"Infect. Immun."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"104064","DOI":"10.1016\/j.psj.2024.104064","article-title":"Trifolium pratense as a novel phytogenic supplement, is an anticoccidial agent in chickens","volume":"103","author":"Lien","year":"2024","journal-title":"Poult. Sci."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Conway, D.P., and McKenzie, M.E. (2007). Poultry Coccidiosis: Diagnostic and Testing Procedures, John Wiley & Sons. [3rd ed.].","DOI":"10.1002\/9780470344620"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Mesa-Pineda, C., Navarro-Ru\u00edz, J.L., L\u00f3pez-Osorio, S., Chaparro-Guti\u00e9rrez, J.J., and G\u00f3mez-Osorio, L.M. (2021). Chicken coccidiosis: From the parasite lifecycle to control of the disease. Front. Vet. Sci., 8.","DOI":"10.3389\/fvets.2021.787653"},{"key":"ref_23","unstructured":"Hector, M., Cervantes, L.R.M., and Jenkins, M.C. (2020). Protozoal Infections. Diseases of Poultry, John Wiley & Sons. [14th ed.]."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Pietruk, K., Karamon, J., Jedziniak, P., Tokarzewski, S., and Olejnik, M.J.A. (2025). Influence of Eimeria spp. and Clostridium perfringens infection on growth performance and toltrazuril residues in chickens. Animals, 15.","DOI":"10.3390\/ani15020216"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"114","DOI":"10.1111\/j.1574-695X.2008.00458.x","article-title":"Campylobacter colonization of the chicken induces a proinflammatory response in mucosal tissues","volume":"54","author":"Smith","year":"2008","journal-title":"FEMS Immunol. Med. Microbiol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1186\/s13071-020-3897-6","article-title":"Dissection of the cecal microbial community in chickens after Eimeria tenella infection","volume":"13","author":"Chen","year":"2020","journal-title":"Parasit Vectors"},{"key":"ref_27","first-page":"1","article-title":"Exploring the interplay between Eimeria spp. infection and the host: Understanding the dynamics of gut barrier function","volume":"45","author":"Chen","year":"2025","journal-title":"Vet. Q."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1561","DOI":"10.14202\/vetworld.2025.1561-1570","article-title":"Prevalence and anticoccidial drug sensitivity of Eimeria tenella isolated from commercial broiler farms in Thailand","volume":"18","author":"Tongkamsai","year":"2025","journal-title":"Vet. World"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Liao, S., Lin, X., Zhou, Q., Wang, Z., Yan, Z., Wang, D., Su, G., Li, J., Lv, M., and Hu, J. (2024). Epidemiological investigation of coccidiosis and associated risk factors in broiler chickens immunized with live anticoccidial vaccines in China. Front. Vet. Sci., 11.","DOI":"10.3389\/fvets.2024.1375026"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Xu, L., Xiang, Q., Li, M., Sun, X., Lu, M., Yan, R., Song, X., and Li, X. (2022). Pathogenic effects of single or mixed infections of Eimeria mitis, Eimeria necatrix, and Eimeria tenella in chickens. Vet. Sci., 9.","DOI":"10.3390\/vetsci9120657"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1080\/03079459208418846","article-title":"Effect of chemicals on the infectivity of chicken anaemia virus","volume":"21","author":"Yuasa","year":"1992","journal-title":"Avian Pathol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"435","DOI":"10.3347\/kjp.2014.52.4.435","article-title":"Suppression of Eimeria tenella sporulation by disinfectants","volume":"52","author":"You","year":"2014","journal-title":"Korean J. Parasitol."},{"key":"ref_33","first-page":"493","article-title":"A simple method of estimating fifty per cent endpoints","volume":"27","author":"Reed","year":"1938","journal-title":"Am. J. Hyg."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1007\/s12250-020-00230-5","article-title":"On the calculation of TCID 50 for quantitation of virus infectivity","volume":"36","author":"Lei","year":"2021","journal-title":"Virol. Sin."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1","DOI":"10.14411\/fp.2009.001","article-title":"Effect of pine bark (Pinus radiata) extracts on sporulation of coccidian oocysts","volume":"56","author":"Molan","year":"2009","journal-title":"Folia Parasit."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"30","DOI":"10.1016\/0014-4894(70)90063-9","article-title":"Anticoccidial drugs: Lesion scoring techniques in battery and floor-pen experiments with chickens","volume":"28","author":"Johnson","year":"1970","journal-title":"Exp. Parasitol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"990","DOI":"10.3382\/ps.2010-01228","article-title":"Eimeria tenella oocyst shedding and output in cecal or fecal contents following experimental challenge in broilers","volume":"90","author":"Jordan","year":"2011","journal-title":"Poult. Sci."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Tongkamsai, S., Lee, M.-S., Tsai, Y.-L., Chung, H.-H., Lai, G.-H., Cheng, J.-H., Cheng, M.-C., and Lien, Y.-Y. (2019). Oral inoculation of specific-pathogen-free chickens with chicken anemia virus induces dose-dependent viremia and transient anemia. Pathogens, 8.","DOI":"10.3390\/pathogens8030141"},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Tongkamsai, S., Lee, M.S., Cheng, M.C., Chaung, H.C., Tsai, Y.L., and Lien, Y.Y. (2019). Persistent infection with chicken anemia virus in 3-week-old chickens induced by inoculation of the virus by the natural route. Pathogens, 8.","DOI":"10.3390\/pathogens8020048"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1186\/s13567-016-0383-4","article-title":"The impact of co-infections on fish: A review","volume":"47","author":"Kotob","year":"2017","journal-title":"Vet. Res."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"552","DOI":"10.1038\/nrmicro928","article-title":"Developing animal models for polymicrobial diseases","volume":"2","author":"Bakaletz","year":"2004","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/j.pt.2018.11.007","article-title":"Importance of sequence and timing in parasite coinfections","volume":"35","author":"Karvonen","year":"2019","journal-title":"Trends Parasitol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"803","DOI":"10.2307\/1591002","article-title":"Experimental cryptosporidiosis and infectious bursal disease virus infection of specific-pathogen-free chickens","volume":"32","author":"Levy","year":"1988","journal-title":"Avian Dis."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1080\/01652176.2014.991048","article-title":"The effect of infection with mixed Eimeria species on hematology and immune responses following Newcastle disease and infectious bursal disease booster vaccination in broilers","volume":"35","author":"Akhtar","year":"2015","journal-title":"Vet. Q."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"254","DOI":"10.1080\/03079450600717349","article-title":"Chicken anaemia virus inoculated by the oral route causes lymphocyte depletion in the thymus in 3-week-old and 6-week-old chickens","volume":"35","author":"Smyth","year":"2006","journal-title":"Avian Pathol."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1007\/s00018-022-04252-y","article-title":"The impact of the gut microbiota on T cell ontogeny in the thymus","volume":"79","author":"Geuking","year":"2022","journal-title":"Cell Mol. Life Sci."}],"container-title":["Microorganisms"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2607\/13\/7\/1676\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:10:51Z","timestamp":1760033451000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2607\/13\/7\/1676"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,7,16]]},"references-count":46,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2025,7]]}},"alternative-id":["microorganisms13071676"],"URL":"https:\/\/doi.org\/10.3390\/microorganisms13071676","relation":{},"ISSN":["2076-2607"],"issn-type":[{"value":"2076-2607","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,7,16]]}}}