Brotogerid parakeets, ringneck and related parakeets, amazons, Grey Cheeks, and pionus parrots seem to be especially susceptible. Although sudden death can occur in a bird with normal body weight, the usual presentation of a bird with TB is one of progressive weight loss in spite of a good appetite. Depression, diarrhea, increased thirst, and respiratory difficulty may also be present. Decreased egg production often occurs in birds that were laying eggs. Once the disease appears, it is impossible to eliminate.
Eventual death is the usual outcome.
Oral ingestion of food and water contaminated with feces is the most common method of infection. Once ingested, the organism spreads throughout the bird's body and is shed in large number in the feces. If the bacterium is inhaled, pulmonary lesions may develop. Skin invasion may occur as well. Although spread via infected eggs can occur, it is not a common means of dissemination.