Fowl Cholera

This is an acute, contagious disease causing heavy mortality but sometimes subacute and chronic forms may also occur. Pasteur was the first to attenuate this organism in 1880 and probably make the first vaccine in the world.

Etiology
The disease is caused by a gram negative, capsulated, bipolar. nonmotile, bacteria called pasteuteula multocida, There are several strains which differ in virulence hence there are variation in severity of disease, lesions and mortality (acute, subacute and chronic forms).

P.multocida are of type A, which are indole positive. the system based on gel diffussion precipitin (GDP)

Resistance to chemicals
The organisms are killed by 1% formalin, 1% caustic soda and 1% phenol and by most of the modern disinfectant given under the chapter on disinfectants.

Aymptoms
Loss of appeite, bluishness of combs, wattles, catarrhal discharge from nostril, fever. prostration, drolling of saliva, and diarrhoea.
diarhoea later becomes yellowish and greenish. Death occurs due to dehydration and septicaemia, and varies between 15 to 90 per cent, depending on the strain of the causal organism.
In 3-6 week old broilers the birds revealed 'getting down' on legs and dying.

Chronic Form
This Form of the disease may be seen in terminal stage of an outbreak or as sporadic cases. Most common form is oedema of wattles, combs and sometimes as otitis,arthritis etc.

Pathology.
In acute form, petechial haemorrhages on heart, occasionally on gizzard muscles, proventriculus and serosa of intestines and abdominal fat are common.
there is venous congestion of internal organs. sepecially abdominal organs, causing enlargement and dark colouration of liver, kidneys and spleen, ova may be congested of ruptured.

Enteritis is almost a constant feature. Fibrinous covering on airsacs, liver and heart may be seen. lungs may be congested and sometimes consolidated due to pneumonia. In some cases, liver show pin point sized, necrotic spots all over the liver parenchyma.

In chronic forms, the affected wattles, combs or joints show yellowish, thick pus or cheesy exudate. Conjunctivitis and facial oedema may also be seen.

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