Causative agent
- Mycoplasma gallisepticum
- Mycoplasma synoviae
Differential diagnosis
- Infectious corya
- Infectious bronchitis
- Infectious laryrigotracheitis
- Avian colibacillosis
1. History taking
- Adverse environment (overcrowding, poor
ventilation) increases incidence
- Mixed infections are common in the field
- Vaccination with live virus vaccine may induce
the disease
- Chronic respiratory symptoms with low mortality
- Synovitis is rarely found
- Transmission rate is relative slow
2. Clinical examination
- Sinusitis, catarrhal exudate in respiratory tract
- Labored breathing with open mouth, tracheal rales
- Swelling and induration of head and eyelids
- Joint swelling with fluctuation, lameness
3. Necropsy
- Catarrhal exudate in respiratory tracts
- Sinusitis, bronchitis, airsacculitis, pericarditis,
perihepatitis, pnuemonia
- Lymphofollicular appearance in air sacs (beading
reaction)
- Accumulation of cheesy material in air sacs of dead
embryo in shell
- Synovitis with creamy to gray exudate in synovial
membranes of joint
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4. Histopathological observation
- Thickening of mucous membrane of affected tissue
due to infiltration of mononuclear cells and
hyperplasia of mucous glands
- Focal areas of lymphoid hyperplasia in submucosa
- Pneumonic areas in lung with lymphofollicular
change
- Hyperplasia of synovial membrane of joint with
villous formation and diffuse or nodular infiltration
of lymphocytes and macrophages in subsynovia
5. Bacterial isolation
Specimen : exudate of nasal cavity, trachea, air sac,
joint cavity and lung tissue emulsion
Medium : Modified Chanock's and Frey's medium
for MG and MS, respectively
- Culture : 0.2 ml. of emulsion is inoculated into
liquid medium and incubated at 37°C for 1 week.
After color changes, 1 drop of cultured broth is
spread onto the above agar medium and incubated
at 37°C for 3-5 days under 5% CO2 condition
- Colony morphology : typical nipple shaped colonies
(a tiny circular mass with a dense raised central
area)
6. Serological test
- Plate or tube agglutination test, HI test
Control
- Vaccination in parent stock are available
- Improvement of rearing environment
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