MYCOBACTERIOSIS CAUSED BY MYCOBACTERIUM GENAVENSE IN BIRDS KEPT IN A ZOO - 11-YEAR SURVEY

We report on a disease in 27 birds (1 bird belonging to the order Cora ciiformes, 3 to Piciformes, 4 to Galliformes, 7 to Psittaciformes, and 12 to Passeriformes) caused by fastidious mycobacteria, All birds wer e caged at the Antwerp Zoo and died suddenly between 1983 and 1994, Se venteen birds had no previous signs of disease, and 10 birds showed em aciation, Gross necropsy findings were generally nonspecific, but all the birds were smear positive for acid-fast bacilli (AFB), Histopathol ogic evaluation performed on 14 birds revealed predominantly intracell ular AFB, Extracellular AFB were more abundant in advanced lesions, es pecially in necrotic areas, In the intestine the mucosal area was gene rally heavily infiltrated, suggesting an intestinal origin of the infe ction, There was extensive invasion of the lungs in most birds. In 11 birds sparse growth was obtained after at least 6 months of incubation on Lowenstein-Jensen medium or on Ogawa medium supplemented with myco bactin. Subculture was unsuccessful in all instances. The 16S rRNA gen e sequence of the cultured organisms or tissues from seven birds revea led the characteristic signature sequence for Mycobacterium genavense. Direct bird-to-bird transmission in the zoo was unlikely, and the pat hogenicity of M. genavense in birds seems to be limited, The source of M. genavense in nature and the epidemiology of the disease in birds r emain obscure. As suspected for human cases of M. genavense infection, an oral route of infection has been suggested, and contaminated local water distribution systems may have been the source of the infection, Our study confirms that infections caused by M. genavense should be s uspected in birds (especially in Passeriformes and Psittaciformes orde rs) that die suddenly without previous symptoms and that have AFB in t issues that are difficult to grow on conventional media.