mycoplasma synoviae and pasteurella gallinarum infection

Out break of disease with heavy mortality in broiler has been reported from U.S.A. due to combined infection of M.synoviae and atypical strain of pasteurella gallinarum. The P.gallinarum isolated from outbreak was confirmed as pathogencity test.

Sign
Coughing started on day 45 and mortality rose up to 3rd week of age.
Mortality declined during 4th week and rose again during 5weeks of age, achieving peak in 7th week. Mortality varied from 8.4 to 14% at onset 48.1 to 59.8% during peak.

Pathology
Predominent lession were as follows

1. mucoid tracheitis (about 75% cases)
2. fibrinopurulent pericarditis (about 65% cases)
3. thick fibrinopurulent exudate on liver (about 60% cases)
4. air succulitis (about 55% cases)
5. purulent synovitis of hock joint (about 18% cases)
6. congestion and dark foci in lungs (about 15% cases)
7. caseous plaques in upper oesophagus
8. bursae in all casses appreated atrophic

Histopathology
Moderate to sever inflammation of trachea, epithelial cell hyperlplasia and loss of cilia of epihelum were observed. lamina propria revealed lymphocytic infiltration, heterophilic infiltration or purulent exudate was found in tracheal lumen. there is fibrinopurulent pericarditis, fibrinous, perihepatitis, fibrino purulent air sacculitis and purulent synovitis of tibiotarsal joint.

Diagnosis
P.gallinarum can be isolated from pericardium, joints, liver and air sacs on 5% sheep blood agar or macConkey's agar on incubation at 37'C in 7.5 % Co2, M.synoviae were isolated and modified frey's agar and then inoculation in to modified frey's both. Consecutive weekly subculture is attempted before declaring negative.
Pathogenicity test of P.gallinarum should be done because P.gallinarum isolated from upper respiratory tract are nonpathogenic. It's isolation from internal organs (pericardium air sacs and liver) should be one step in confirming pathogenicity.
As a second step intramuscular inoculation of 3 week old healthy chicks should reproduce lession as described above.

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