Experimental reproduction of Mycoplasma gallisepticum disease in chukar partridges (Alectoris graeca)

An outbreak of conjunctivitis and severe respiratory disease occurred in an integrated chukar partridge (Alectoris graeca) operation that involved about 8000 birds. The main clinical features were conjunctivitis and sinusitis and frequent mouth breathing, but almost no gasping or coughing. In 1000 breeders, egg production declined from 73% to 20%. Morbidity reached 100%, and losses from mortality and culling approached 60%. At necropsy, a conjunctivitis (often bilateral) and extensive caseated sinusitis were common. There was an occasional slight mucoid tracheitis, but no significant air sac lesions were noted. Mycoplasma gallisepticum, designated strain GM1125, was isolated and identified. Exposure of susceptible chukars to GM1125 reproduced the field disease. GM1125 was reisolated from the conjunctiva of all exposed birds 12 days postinfection, but infrequently from there or the respiratory system 36 days postexposure, even though clinical disease was still present. The experimental disease was confined to the conjunctiva and the upper respiratory tract. An occasional mucoid tracheitis was noted, but generally, the lungs and air sacs were not involved. Infection was followed by an appreciable serological response to M. gallisepticum.