Mycoplasmas are widespread bacteria in domestic and wild birds. Among the important species in laying hen, Mycoplasma gallisepticum and Mycoplasma synoviae, are considered as an emergent pathogen in the last few years worldwide, causing considerable economic losses as a result of falling eggs and the decrease in egg quality. Transmission of M. synoviae occurs horizontally, more rapidly in multi-age sites, and vertically, leading to a decline in hatchability in breeding farms. The interaction between M. synoviae and the host’s immune system explains the immunosuppression induced by this pathogen. Inside the cell, M. synoviae can escape the immune system by implementing several mechanisms.
Subclinical respiratory infection is oft en associated to M. synoviae. However, severe disease may be observed in the presence of other factors (respiratory viruses, stressors). The emergence of a new form of clinical manifestation of disease associated to M. synoviae infection has been described since the 2000s. Eggshell apex abnormalities of the produced eggs, associated to high risk of cracks and breakage, is described.
The diagnosis of M. synoviae infection is based on various tests, including serology, culture and biomolecular methods. Control is based on the
acquisition of free mycoplasma birds, biosecurity, regular monitoring and vaccination. Management of other risk factors is essential.