Mycoplasma synoviae

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Mycoplasma synoviae
Phylum Firmicutes
Class Mollicutes
Order Mycoplasmatales
Family Mycoplasmataceae
Genus Mycoplasma
Species M.synoviae

Also Known As: Infectious SynovitisAvian MycoplasmosisInfectious SinusitisMycoplasma Arthritis


M. synoviae causes bacterial disease affecting the joints, bones and respiratory system of birds. It is one of the mycoplasma genus of bacteria.

M; synoviae shares some antigens with M. gallisepticum which causes chronic respiratory disease in poultry, but is distinct by most serological tests.

M. synoviae is endemic in parts of Europe and causes significant production losses particularly in egg production. Very recently the mycoplasma has been associated with eggshell apex abnormalities (EAA)[1].


Thought to be worldwide but recording is unreliable.

Mycoplasma can be transmitted to progeny through eggs and through direct and indirect contact between birds.


The bacterium affects mainly chickens and turkeys, with chickens being the most susceptible. It can also affect game and wild birds.

Clinical Signs

Most birds exhibit lameness, abnormal curvature of the limbs, deviation of the limbs and feet and a stiff gait. Dehydration and decreased production usually manifest and birds are reluctant to move.

Tachypnoea, sneezing, purulent nasal discharge and open mouth breathing are common but non-specific.

Torticollis and other neurological signs may occur in some severe cases.

EAA is characterised by defects at the apex (pointed end) of the egg consisting of sharp clearly defined discoloured zones which are thin, soft and fragile. It can result in a significant drop in egg quality and production.


Clinical signs and necropsy findings are suggestive but not pathognomonic so laboratory diagnosis is necessary.

On post-mortem, air sacculitis and arthritis with a caseous exudate are evident.

Bacteria can be isolated and cultured from wet swabs of the trachea, oropharynx, eye, nose or cloaca in live birds. If sampling a dead bird, sterile samples of synovial fluid and air sac samples should be taken.

M. synoviae can then be definitively identified by immunofluorescence and PCR.

ELISAs can be used for serological diagnosis and are excellent for detecting antibodies in egg yolk which is valuable for flock status investigation. However the slide agglutination test (SAT) is still widely used in industry.

Specific immunoblotting tests are available in some specialist laboratories to confirm results of the ELISAs and SATs.


M. synoviae is susceptible to tilmicosin, tylosin, enrofloxacin and oxytetacyclines in vitro but resistance is increasing in vivo.

Eggs can be dipped in cold chlortetracycline antibiotic solution for 15-20 minutes or heat treated to 46-47⁰ for 11-14 hours prior to incubation.


Control is hampered by the increasing resistance of M. synoviae to antibiotics.

A vaccine containing a temperature-sensitive strain (MS-H) of Mycoplasma synoviae is currently used in many countries around the world. The duration of protective immunity is at least 40 weeks and has been shown to be protective against EAA.

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  1. Catania, S., Bilato, D., Gobbo, F., Granato, A., Iob, L and Nicholas R.A.J. (2010) Treatment of egg-shell abnormalities and reduced egg production caused by Mycoplasma synoviae infection. Avian Diseases 54, 961-964


This article was originally sourced from The Animal Health & Production Compendium (AHPC) published online by CABI during the OVAL Project.

The datasheet was accessed on 6 June 2011.

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