Eimeria labbeana is a major pathogen of pigeon coccidiosis,causing damage to the intes-tinal epithelial cells of pigeons,which leads to gut injury,diarrhea,decreased production perform-ance,and even death.There have been no research on the pathogen characteristics of isolated strains in China.In this study,1 008 fecal samples were collected from nine cities in Zhejiang Prov-ince,including Hangzhou,Ningbo,Wenzhou,Shaoxing,Huzhou,Jinhua,Quzhou,Taizhou and Lishui.The samples were examined using the McMaster counting method to quantify oocysts per gram of feces,and coccidia species in positive samples were identified through microscopy.Patho-gens were isolated and purified with methods of single oocyst pickout under the microscopy and passage in coccidia-free pigeon,followed by a detailed study of their characteristics.Our findings demonstrated an overall infection rate of 55.8％(562/1 008)for pigeon coccidia in the surveyed ar-eas,with E.labbeana present across all farms.A strain of E.labbeana isolated from Zhejiang was successfully obtained and designated E.labbeana-ZJ.PCR identification and sequence alignment showed that this Zhejiang isolate shared a 99.67％similarity in the 18S rRNA gene sequence with the Australian strain(KT305927.1)and clustered into a small subgroup.Pathogenicity and oocyst shedding patterns were assessed through animal infection experiments,revealing a 4 days latent period,with peak infection occurring on the 8th day.Following infection,notable clinical symptoms emerged,with significant intestinal damage,and changes in body weight,indicating moderate path-ogenicity.The results enriched the epidemiological survey data of pigeon coccidiosis in China,and provide a new basis for further research and effective control measures against pigeon coccidiosis.

Toxoplasma gondii is a single-celled parasite that infects nearly all warm-blooded animals, including humans (Montoya and Liesenfeld, 2004). It occurs worldwide and can persist for a lifetime in mammals. Humans get infected by eating undercooked meat of animals containing the tissue cysts of this parasite. In immune-competent individuals, T. gondii infection usually does not cause significant clinical symptoms, whereas in pregnant or immunocompromised individuals, T. gondii infection (toxoplasmosis) can cause more serious problems like abortion and even death (Dunn et al., 1999; Wang et al., 2017). A combination of pyrimethamine and sulfadiazine is usually used to treat toxoplasmosis, although it is generally inefficient and causes side effects (Alday and Doggett, 2017). Worse still, there is a lack of vaccines to prevent T. gondii infection in humans or animals.
Toxoplasma/enzymology* ; Animals ; Humans ; Toxoplasmosis ; Mitochondria/enzymology* ; Protozoan Proteins/metabolism*

Eimeria labbeana is a major pathogen of pigeon coccidiosis,causing damage to the intes-tinal epithelial cells of pigeons,which leads to gut injury,diarrhea,decreased production perform-ance,and even death.There have been no research on the pathogen characteristics of isolated strains in China.In this study,1 008 fecal samples were collected from nine cities in Zhejiang Prov-ince,including Hangzhou,Ningbo,Wenzhou,Shaoxing,Huzhou,Jinhua,Quzhou,Taizhou and Lishui.The samples were examined using the McMaster counting method to quantify oocysts per gram of feces,and coccidia species in positive samples were identified through microscopy.Patho-gens were isolated and purified with methods of single oocyst pickout under the microscopy and passage in coccidia-free pigeon,followed by a detailed study of their characteristics.Our findings demonstrated an overall infection rate of 55.8％(562/1 008)for pigeon coccidia in the surveyed ar-eas,with E.labbeana present across all farms.A strain of E.labbeana isolated from Zhejiang was successfully obtained and designated E.labbeana-ZJ.PCR identification and sequence alignment showed that this Zhejiang isolate shared a 99.67％similarity in the 18S rRNA gene sequence with the Australian strain(KT305927.1)and clustered into a small subgroup.Pathogenicity and oocyst shedding patterns were assessed through animal infection experiments,revealing a 4 days latent period,with peak infection occurring on the 8th day.Following infection,notable clinical symptoms emerged,with significant intestinal damage,and changes in body weight,indicating moderate path-ogenicity.The results enriched the epidemiological survey data of pigeon coccidiosis in China,and provide a new basis for further research and effective control measures against pigeon coccidiosis.