Epidemiological investigation of coccidiosis and associated risk factors in broiler chickens immunized with live anticoccidial vaccines in China

Shenquan Liao; Xuhui Lin; Qingfeng Zhou; Zhanxin Wang; Zhuanqiang Yan; Dingai Wang; Guanzhi Su; Juan Li; Minna Lv; Junjing Hu; Haiming Cai; Yongle Song; Xiangjie Chen; Yibin Zhu; Lijun Yin; Jianfei Zhang; Nanshan Qi; Mingfei Sun

doi:10.3389/fvets.2024.1375026

Epidemiological investigation of coccidiosis and associated risk factors in broiler chickens immunized with live anticoccidial vaccines in China

Front Vet Sci. 2024 Mar 19:11:1375026. doi: 10.3389/fvets.2024.1375026. eCollection 2024.

Authors

Shenquan Liao^#¹, Xuhui Lin^#¹, Qingfeng Zhou², Zhanxin Wang², Zhuanqiang Yan², Dingai Wang², Guanzhi Su², Juan Li¹, Minna Lv¹, Junjing Hu¹, Haiming Cai¹, Yongle Song¹, Xiangjie Chen¹, Yibin Zhu¹, Lijun Yin¹, Jianfei Zhang¹, Nanshan Qi¹, Mingfei Sun¹

Affiliations

¹ Key Laboratory of Livestock Disease Prevention of Guangdong Province, Key Laboratory of Avian Influenza and Other Major Poultry Diseases Prevention and Control, Ministry of Agriculture and Rural Affairs, Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China.
² Wen's Group Academy, Wen's Foodstuffs Group Co., Ltd., Xinxing, Guangdong, China.

^# Contributed equally.

Abstract

Coccidiosis is a costly intestinal disease of chickens caused by Eimeria species. This infection is associated with high mortality, reduced feed efficiency, and slowed body weight gain. The diagnosis and control of coccidiosis becomes challenging due to the fact that chickens can be infected by seven different Eimeria species and often occur mixed-species co-infections. Grasping the epidemiology of Eimeria species is crucial to estimate the efficiency of poultry management. This study aimed to explore the distribution of Eimeria species in broiler chickens in China after administering live anticoccidial vaccines. A total of 634 samples were obtained, and the survey results showed that the prevalence of Eimeria was 86.12% (546/634), and the most common species were E. acervulina (65.62%), E. necatrix (50.95%), E. mitis (50.79%), E. tenella (48.42%), and E. praecox (41.80%). Most samples indicated mixed-species infections (an average of 3.29 species per positive sample). Notably, 63.98% of samples contain 3 to 5 Eimeria species within a single fecal sample. The most prevalent combinations were E. acervulina-E. tenella (38.96%) and E. acervulina-E. necatrix (37.22%). Statistical analysis showed that flocks vaccinated with trivalent vaccines were significantly positive for E. necatrix in grower chickens (OR = 3.30, p < 0.05) compared with starter chickens, and tetravalent vaccinated flocks showed that starter chickens demonstrated a higher susceptibility to E. tenella-E. brunetti (OR = 2.03, p < 0.05) and E. acervulina-E. maxima (OR = 2.05, p < 0.05) compared with adult chickens. Geographically, in the case of tetravalent vaccine-immunized flocks, a substantial positive association was observed between E. necatrix infection rates and flocks from eastern (OR = 3.88, p < 0.001), central (OR = 2.65, p = 0.001), and southern China (OR = 3.17, p < 0.001) compared with southwestern China. This study also found a positive association between E. necatrix (OR = 1.64, p < 0.05), E. acervulina (OR = 1.59, p < 0.05), and E. praecox (OR = 1.81, p < 0.05) infection and coccidiosis occurrence compared with non-infected flocks in tetravalent vaccinated flocks. This molecular epidemiological investigation showed a high prevalence of Eimeria species in the field. The emergent species, E. brunetti and E. praecox, might be incorporated into the widely-used live vaccines in the future. These insights could be useful in refining coccidiosis control strategies in the poultry industry.

Keywords: Eimeria spp.; broiler chicken; coccidiosis; prevalence; risk factors.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This study was supported by the National Key Research and Development Program of China (2023YFD1801205), The open competition program of top ten critical priorities of Agricultural Science and Technology Innovation for the 14th Five-Year Plan of Guangdong Province (2023SDZG02), Key Realm R&D Program of Guangdong Province (2023B0202150001), Opening Project of State Key Laboratory of Swine and Poultry Breeding Industry (2023QZ-NK05, 2022GZ07), Science and technology project of Yunfu (2022020202), Science and technology project of Guangzhou (2023B04J0137, 2023A04J0789), Special fund for scientific innovation strategy-construction of high level Academy of Agriculture Science (202110TD, 202122TD, R2020PY-JC001, R2019YJ-YB3010, R2020PY-JG013, R2020QD-048, R2021PY-QY007, R2023PY-JG018), The Project of Collaborative Innovation Center of GDAAS (XTXM202202).