Tuberculosis (Mycobacteriosis)

By James M. Harris, BS, DVM, FRSH
Mayfair Veterinary Clinic, Hobart

Mycobacteriosis is a chronic infectious disease of animals, birds, reptiles, fish, and humans caused by Mycobacterium species, characterized by inflammatory and necrotic processes. Mycobacterium avium-intracellulare-scrofulaceum (MAIS) complex and Mycobacterium tuberculosis affect birds. MAIS complex serotypes 1, 2, and 3 are responsible pathogens in birds.

M. Tuberculosis in birds is acquired from infected humans and appears as skin lesions and lesions around the nostrils. The disease in all species is insidious, and all susceptible species acquire the infection from the environment. Human pulmonary (lung) infections are acquired via aerosols through the respiratory tract. Avian tuberculosis is acquired through the digestive tract from contaminated food, water, and soil. MAIS is relatively resistant to antituberculosis theorapy. Active infections in humans can be fatal.

M. avian has an exceptionally long-term survival, from months to years, in the environment, and efforts should be made to prevent contamination. Infected birds, either domestic fowl or pet species should not be maintained. Chronically infected birds are emaciated. The disease in avian pecies is primarily associated with the digestive tract and related organs such as the liver and spleen. The organism is shed in the feces in large numbers and is found in infected tissues in large numbers. Birds also exhibit bone and joint infections. Avian mycobacteriosis is common in Brotogerus sp. (Grey Cheek Parakeet), mature Amazon Parrots and domestic poultry.

Diagnosis anti-mortem in avian species may be accomplished by acid-fast stains of fecal smears.There are serious problems with M. avium infections in immune-compromised human populations. Pet birds placed with immune-compromised humans. should be checked for the presence of acid-fast organisms. It would be appropriate to re-test these birds periodically, semi-annually and at any time that unexplained weight loss occurs.

Experimental treatment has apparently been successful in some birds. It is questionable if infected birds should be kept as companions and definitely not with other birds. It has been this writers experience that warning owners about the dangers of avian tuberculosis rarely results in the owners giving up the bird. This is a serious situation if other birds are on the premises or there are health issues with family members.

New antituberculous medications used in humans may be efficacious in pet avian species Treatment is long term, for a year or more and is monitored by serial acid-fast stains of feces and blood counts.

Avian tuberculosis has become common in patients tested positive for acquired immune-deficiency syndrome (AIDS). AIDS patients would be well advised to avoid species of birds with a known high incidence of this disease. Note that fecal acid-fast stains are often negative in positive avian tuberculosis cases if lesions are found in the liver, spleen, or bones and not in the gastrointestinal tract lumen.

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