Avian tuberculosis

Tuberculosis in poultry has not remained a big threat in list of diseases due to commercialization of poultry business. It is a contagious chronic disease caused by Mycobacterium avium. The causative bacterium is an acid-fast bacillus that persists in the soil and litter for long time even upto 4 years. Domestic fowls and captive exotic birds are frequently affected. The disease is also seen in ducks, geese, swan, peacocks and turkeys. Infected birds act as the source of infection. Infected pigs and other mammals also spread the disease.

Symptoms and lesions: The disease pattern is the same as with the other tuberculosis.

There is progressive debility, loss of appetite and sometimes persistent diarrhea. Lesions are mainly seen in the liver, spleen and intestine. They appear as small whitish or grayish nodules. There may be enlargement of liver with fatty degeneration with occasional involvement of other visceral organs. Microscopic examination of crushed nodules on acid-fast staining shows large number of acid-fast bacteria in bunches. A well formed tubercular granuloma has necrosed areas surrounded by a massive cellular collection of giant cells, epitheloid cells, macrophages and lymphocytes.

Prevention and control: This is not the disease of commercial poultry, but if once allowed to enter on a premise, may create difficulties in control unless the flock is entirely removed and biosecurity measures strictly enforced. Treatment is not generally done, but can be tried in valuable exotic birds maintained in captivity. A combination of isoniazid (30mg/kg) ethambutol (30mg/kg) and rifampicin (45mg/kg) for prolonged period was found effective. For controlling the disease, it is necessary to avoid all sources of infection; providing good sanitation and management and removal of reactors.