Michele Miller1, DVM, MPH, PhD; Peter Buss2, BVSc, MMedVet; Jennifer Hofmeyr2, BTech(Vet), BSc(Hon); Eliza Stout3, BS; Francisco Olea-Popelka3,4, DVM, MS, PhD; Konstantin Lyashchenko5, PhD; Sven Parsons1, BVSc, MSc, PhD; Paul van Helden1, PhD
1DST/NRF Centre of Excellence for Biomedical TB Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa; 2Veterinary Wildlife Services, South African National Parks, Kruger National Park, Skukuza, South Africa; 3Applied Veterinary Epidemiology (AVE) Research Group, Colorado State University, Fort Collins, CO, USA; 4Department of Clinical Sciences and Mycobacteria Research Laboratories, Colorado State University, Fort Collins, CO, USA; 5Chembio Diagnostic Systems, Inc., Medford, NY, USA
Tuberculosis has been a growing concern in the free-ranging lion population in Kruger National Park since its initial discovery in 1995.1 Understanding the impact of tuberculosis on lions requires accurate methods of detecting pathogenic mycobacterial infection. Therefore, we undertook a study to identify and evaluate associations between culture results and other immunological tests.
Samples were collected in Kruger National Park from 242 free-ranging immobilized lions and a cohort of 31 necropsied lions. Sera were tested using the ElephantTB STAT-PAKa, as previously described.2 One hundred and forty-five tracheal lavage samples were obtained for mycobacterial culture using an adapted field technique and typing was used to identify different mycobacterial species. The tuberculin skin test (TST) was performed in 44 of these lions.
Mycobacterium species were identified in 50 lions. Fifteen isolates were M. bovis (8 ante-mortem and 7 post-mortem samples) and the remaining 35 isolates were classified as species belonging to non-tuberculous mycobacteria (NTM). All M. bovis-infected lions with TST results had positive reactions. Nine out of fourteen lions that were M. bovis-infected were seropositive on STAT-PAK (64.3%). In 16 lions with skin test results from which NTMs were isolated, the majority (81.2%) reacted positively to the skin test. There were only 3 STAT-PAK positive results out of 35 NTM-positive lions tested (8.6%); none were positive using VetTB DPPa. These results suggest that the role of different mycobacterial infections on immunological responses used for screening and diagnosing TB in lions deserves further attention.
a. Chembio Diagnostics Systems, Inc.
The authors thank Morris Animal Foundation for their financial support of this project through Grant #D10ZO-039. In addition, the authors acknowledge the contributions of the veterinary and capture teams of South African National Parks for their crucial role in obtaining lion samples.
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2. Miller M, Joubert J, Mathebula N, De Klerk-Lorist L, Lyashchenko KP, Bengis R, van Helden P, Hofmeyr M, Olea-Popleka F, Greenwald R, Esfandiari J, Buss P. Detection of antibodies to tuberculosis antigens in free-ranging lions (Panthera leo) infected with Mycobacterium bovis in Kruger National Park, South Africa. J Zoo Wildl Med. 2012;43:317–323.