Mycoplasma synoviae


Mycoplasma synoviae (MS) is involved in the occurrence of chronic respiratory diseases in chickens and infectious sinusitis in turkeys.

This bacterium is also pathogenic in the joints and the reproductive system in poultry. These infections cause significant economic losses due to growth retardation, mortality, decline in egg laying and condemnation due to aerosacculitis and synovitis lesions.

The prevalence of SM is increasing worldwide, with increasingly pathogenic strains. When this increase is observed, the economic consequences are considered significant, even in the absence of obvious clinical signs.

Transmission is mainly vertical (transovarial) at first; however, most outbreaks result from horizontal transmission, primarily through aerosols and cross-contamination from equipment or staff/visitors. Wild birds probably play a minor reservoir role. The yard is a reservoir that should not be neglected because it is often linked to basic or non-existent biosecurity practices.

The virulence of the MS strain can vary considerably, even in turkeys. In laying hens, some strains may develop an egg apical abnormality, these are more likely to develop it than broiler breeder hens. In chickens, some strains also exhibit respiratory tropism. These strains are generally responsible for subclinical infections characterized by slight reductions in zootechnical performance.


Disinfectants are very effective against mycoplasmas which cannot survive for long hours outside the host.


The best method of control is to keep herds free of mycoplasma. It is important to respect biosecurity measures to avoid contamination and eradicate it. During a mycoplasma infection, the building must be depopulated and the equipment washed and disinfected. The barn must be empty for at least 14 days and the manure heated to a minimum of 37.8°C (100°F) for 4 days. The manure must then be taken out and spread at least 1 km from any henhouse.

Vaccination should only be considered in situations where exposure is unavoidable, such as in multi-age settings. There is currently no live vaccine in Canada; however, approximately 20% of Quebec chicks come from the United States, where vaccination against MS is authorized.

EQCMA intervention protocol in the case of Mycoplasma synoviae mycoplasmosis in commercial pullet and layer flocks in Quebec