The pathogenicity of avian mycoplasmas

Based on literature data and own experiences the author gives an outlook about pathogenicity of avian mycoplasmas. In chickens and turkeys M. gallisepticum and M. synoviae (in addition to it M. meleagridis exclusively in turkeys) are the most important mycoplasmas producing respiratory disease, inflamation of synovial membranes and other lesions. Their pathogenic effect is very much influenced by dose of agent, route of entry of microorganism, age of birds, virulence and tropism of organism as well as associated other mycoplasma or virus or bacterial or fungal infections and conditions of environment. These facts rise difficulties in serological diagnostic and erradication program. Recently ureaplasma infection was also established in chickens and turkeys which can also be associated with respiratory disease. From ducks A. laidlawii, M. anatis and various unclassified strains were isolated, among these M. anatis and unclassified arginine splitting mycoplasma strains proved to be pathogenic. In geese M. gallinarum, A. laidlawii and A. axanthum were detected. A. axanthum showed pathogenicity for goslings and goose embryos. Its effect is exacerbated by associated parvovirus infection.