Agent properties and classification
Avian tuberculosis refers to a disease of birds caused by bacteria of the genus Mycobacterium. Many Mycobacterium species have been identified. They are grouped in different complexes and clades [7]. Not all are pathogens and, from a medical point of view, the M. tuberculosis complex and the M. avium complex are the most important. Both may produce infection in different host species but M. tuberculosis complex infects principally mammals while M. avium complex principally birds [2].
Although the M. avium complex is the primary causes of tuberculosis in birds, also other species of the genus Mycobacterium may cause avian tuberculosis. In an investigation done in the Netherlands on wild birds between 1975 and 1985 [6], on a total of 82 birds found positive to Mycobacterium spp., six different strains were detected, 76 times M. avium, 4 M. fortuitium, 1 M. terrae, 1 M. nonchromogenicum, 1 M. flavescens and 1 not better defined Mycobacterium sp, with 2 cases of coinfection (simultaneous infection by different Mycobacterium species).