Study of Avian Tuberculosis in a Zoo at the Bogota savannah through Tuberculin Testing and Active Epidemiologic Surveillance

Abstract

The flow of wild birds is a weakness in epidemiologic surveillance because of its unknown potential as a source of disease dissemination. The investigation focused on an epidemiological tracking of the mixed wild bird population in a zoo in the Bogota Savannah, where three birds died with a presumptive diagnosis of tuberculosis. In order to verify the presence of Mycobacterium avium and to plan the required measures to avoid risk factors, a control group of five poultry birds of the Hy Line Brown variety that had already been exposed was used, as well as a sentinel group of the poultry birds from the same batch as the control group, and an external control group of 102 birds from cages near the area of the problem. Retrospective and prospective studies were carried out through histopathological, microbiological, epidemiological and molecular analysis. One hundred percent (100%) of the birds from the original cages that died were genotypically diagnosed with tuberculosis caused by Mycobacterium avium. Thirty-five percent (35.5%) of the sentinel group was affected by Mycobacterium avium, 28.6% by Mycobacterium gordonae, 14.3% by Mycobacterium chelonae and 21.4% by a mycobacterium that is very difficult to classify. The other animals outside the cage showed no evidence of infection. It is concluded that the problematic enclosure is affected by avian tuberculosis, which is of high risk both for birds and for humans. The poultry used as sentinels are excellent infective agent detectors, particularly of mycobacteria present in the environment, and the tuberculin test is a good indicator of infection with this type of microorganisms in poultry.