An Outbreak of Histomoniasis in Backyard Sanhuang Chickens.

Histomonas meleagridis is a facultative anaerobic parasite, which can cause a common poultry disease known as histomoniasis. The species and age of the birds impacts on the susceptibility, with turkey being the most susceptible species. Chickens are less susceptible to H. meleagridis than turkeys and usually serve as reservoir hosts. Here, the diagnosis of an outbreak of histomoniasis in backyard Sanhuang chickens is described. The primary diagnosis was made based on clinical symptoms, general changes at necropsy, histopathology, and the isolation and cultivation of parasites. The pathogen was further confirmed by cloning, PCR identification, and animal inoculation tests. A strain of H. meleagri- dis, named HM-JSYZ-C, with a higher pathogenicity level in chickens was obtained. The study lays a foundation for further investigations into H. meleagridis and histomoniasis in chickens.