Characteristic Presentation of Avian Tuberculosis in Different Species of Birds

Zoo and private collections of birds, where a large variety of species are kept in relatively confined spaces, favor the presence and spread of mycobacteria infections. Several mycobacterial species can be involved in the etiology of avian tuberculosis. The disease is most often caused by Mycobacterium avium belonging to serotypes 1, 2, 3, and 6, and M. genavense, while other species are rarely involved [1]. Also in birds, the pathological forms of tuberculosis vary according to the host immune response (related to the species and the individual immunological status), and the specie/serotype of mycobacterium involved. Regarding the host specie susceptibility to disease, Hejlicek and Treml [2] broadly classified bird species into four groups (high, and less susceptible, moderately resistant, and highly resistant). Regarding the anatomic forms of the disease, Gerlach [3] classified typical tuberculoid, diffuse-paratubercoloid, and non-tubercoloid or inapparent forms, often undiagnosed during necropsy. In our series of necropsies (2008-2019), tuberculosis was observed in different species of birds: diffuse intestinal paratubercular form was observed in parrots of the genus Brotogeris spp., and in the Fringillidae of the species Serinus canaria, C. carduelis, Carduelis c. caniceps, C. tristis, C. atrata; the nodular pulmonary form in birds of the genus Euplectes and Ploceus, and in estrildid finches of genus Pyrenestes, while granulomatous-erosive lesions located at the base of the tongue were found only in a Guinea Turaco (Tauraco persa). Authors hypothesize that these particular pathological forms may be linked to some anatomical peculiarities and to the cell-mediated response of the host.