Laboratory Examination and Eradication of a Severe Outbreak of Infectious Sinusitis (Respiratory Mycoplasmosis) in Turkeys with Evidence of Egg-transmission

Abstract

In a detailed study of a severe outbreak of respiratory mycoplasmosis on a large turkey farm in the south of England, egg-transmission of the pathogen (Mycoplasma galliscpticum) was verified by laboratory examination of ‘pipped’ and dead-in-shell embryos, and by the study of 43 poults reared in isolation from 1 day to 19 weeks of age. Maternal HI antibody was found in the sera of these poults up to 4 weeks of age, by which time it had waned, but after this age the pathogen was isolated from typical lesions of mycoplasmosis in the respiratory tract and HI antibody rose to characteristically high titres. The cultural and morphological features of this strain of M. galliscpticum were not altogether typical of the serotype but identification was carried out serologically. No other serotypes of mycoplasma were isolated from the outbreak.Experimental transmission of the pathogen to chickens and turkeys by inoculation of mucous exudate, of broth cultures and by contact with clinically recovered birds was achieved, the strain being unusually pathogenic for turkeys and quick to spread. Chickens did not respond as severely as turkeys, a rise in HI antibody titre often being the only evidence of infection. Complete eradication of this disease by depopulation, disinfection and restocking 3 months later with ‘clean’ birds, which had, fortunately, been hatched and isolated before egg-transmission of mycoplasmosis had begun, was carried out successfully. Sera from birds tested for HI antibody 3 years after the original outbreak were negative.