Disease Risk Assessment of Mycobacterium bovis in African Lions
American Association of Zoo Veterinarians Conference 2011
Margaret Kosmala1, BS; Philip Miller2, PhD; Douglas Armstrong3, DVM; Roy Bengis4, BVSc, MSc, PhD; Peter Buss5, BVSc, MMedVet; Brenda Daly6; Sam Ferreira7, PhD; Paul Funston8, PhD; Markus Hofmeyr5, BVSc, MRCVS, MDP; Dewald Keet9, BVSc, MMedVet; Craig Packer1, PhD; John P. Pollack10, BS
1Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, USA; 2Conservation Breeding Specialist Group, IUCN Species Survival Commission, Apple Valley, MN, USA; 3Omaha’s Henry Doorly Zoo, Omaha, NE, USA; 4State Veterinary Services, Department of Agriculture, Skukuza, South Africa; 5Veterinary Wildlife Services, South Africa National Parks, Skukuza, South Africa; 6Conservation Breeding Specialist Group Southern Africa, Parkview, South Africa; 7Scientific Services, South Africa National Parks, Skukuza, South Africa; 8Department of Nature Conservation, Tshwane University of Technology, Pretoria, South Africa; 9State Veterinary Services, Department of Agriculture, Phalaborwa, South Africa; 10Department of Information Science, Cornell University, Ithaca, NY, USA
In 1995, lions in Kruger National Park were discovered to be infected with Mycobacterium bovis (bovine tuberculosis), a non-endemic disease maintained by the park’s buffalo.1 While M. bovis certainly affects individual animals, it is not known how M. bovis will affect the lion population in Kruger as a whole.
Lions in Kruger contract M. bovis from eating infected buffalo and from other lions (through aerosol transmission and through percutaneous transmission from bite wounds), but measuring these transmission rates directly is difficult.2 We merged a stochastic, spatial, individually-based lion simulation model with a disease model to investigate the relative importance of different modes of M. bovis transmission in Kruger’s lion population. We varied M. bovis transmission rates from buffalo to lion, from mother to cub, from lion to lion within a pride, and from lion to lion between prides within reasonable ranges estimated by experts familiar with the system. We then simulated lion populations and measured population size, disease prevalence, and disease spread over that time. We matched our simulation results against observational data of Kruger’s lions to determine the parameter space of possible disease transmission rates. We then used these rates to forecast lion population size and disease prevalence.
The model suggests that transmission of M. bovis from buffalo to lions dominates the spread of bovine tuberculosis in Kruger National Park. It is therefore likely that lions are a spill-over species for M. bovis and that the prevalence and spread of M. bovis in buffalos will be the biggest predictor of prevalence and spread of M. bovis in the lion population.
1. Keet DF, NPJ Kriek, M-L Penrith, A Michel. Tuberculosis in lions and cheetahs. Proceedings of a Symposium on Lions and Leopards as Game Ranch Animals, Onderstepoort. 1997:151–156.
2. Kee, DF, A Michel, DGA Meltzer. Tuberculosis in free-ranging lions (Panthera leo) in the Kruger National Park. Proceedings of the South African Veterinary Association Biennial Congress. Durban. 2000:232–241.