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S U M M A R YNeospora caninum causes economical impact in cattle-raising farms since it is implicated as the major cause of bovine abortions. Although infection by the parasite has been widely described in mammals, the role of birds in its life-cycle is still obscure. Therefore, this work aimed to evaluate the infection by N. caninum in different chicken models. Experimental infections were conducted in 7-day-old chicks, laying hens and embryonated eggs, where samples were analysed for parasite burden, IgG antibodies and lesions promoted. Chickens demonstrated an asymptomatic infection, although with seroconversion and systemic replication of the parasite. In laying hens, no signs of vertical transmission were observed. However, embryonated eggs inoculated by the allantoic cavity route demonstrated susceptibility to infection, with mortality rates around 50% independent of the inoculum dose. Additionally, dogs became infected after ingestion of different amounts of inoculated eggs, producing either oocysts or specific IgG antibodies. The results herein presented demonstrate that chickens may be intermediate hosts of N. caninum and that embryonated eggs could be a useful model to study the parasite's biology.

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Neospora caninum is a protozoan parasite that presents worldwide distribution and is mainly implicated as responsible for bovine abortion. Although the presence of birds in cattle-raising properties is positively correlated to higher infection rates, very little has been described about the role of these animals in the parasite's life cycle. In that sense, this work aimed to investigate the serological and histological positivity of different avian species sampled in its natural habitat or in captivity. No serological positivity was observed in the 294 tested serum samples. On the other hand, Apicomplexa-like cysts found in muscular tissues of two Psittaciformes were immunostained with N. caninum antisera. These findings indicate that N. caninum may infect a wider range of hosts than described to date, and that further studies should be performed in order to determine the presence of the infection in different avian species.