Tuberculosis in elephants-a reemergent disease: diagnostic dilemmas, the natural history of infection, and new immunological tools.

Tuberculosis (TB) in elephants has been described since ancient times. However, it was not until 1996 when infection with Mycobacterium tuberculosis was identified in a herd of circus elephants that significant research into this disease began. The epidemiology and natural history of TB were unknown in elephants since there had been no comprehensive screening programs, and diagnostic techniques developed for cervidae and bovidae were of unknown value. And, while precepts of test and slaughter were the norm for cattle and deer, this was considered untenable for an endangered species. With no precedent for the treatment of TB in animals, treatment regimens for elephants were extrapolated from human protocols, which guided changes to the Guidelines for the Control of Tuberculosis in Elephants. In the absence of diagnostic testing to confirm cure in elephants, the efficacy of these treatment regimens is only beginning to be understood as treated elephants die and are examined postmortem. However, because of pressures arising from public relations related to elephant husbandry and the added considerations of TB infection in animals (whether real or imagined), sharing of information to aid in research and treatment has been problematic. Here we review the challenges and successes of the diagnosis of tuberculosis in elephants and discuss the natural history of the disease to put the work of Landolfi et al on the immunological response to tuberculosis in elephants in perspective.