Date of Award

1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Veterinary Medical Sciences - Pathobiological Sciences

First Advisor

Martin E. Hugh-Jones

Abstract

The Kruger National Park, (KNP), in the Republic of South Africa, provides a unique opportunity to investigate interesting and unresolved aspects of the epidemiology of the disease anthrax. Anthrax is a disease of primarily mammals caused by the Gram-positive, rod-shaped, spore-forming bacteria Bacillus anthracis. Beyond it's great historical significance anthrax is clearly important in the world today. From a rich legacy of empirical investigations and observations in the form of ecological and epidemiological studies conducted around the world this work endeavors to distill and extract the essence of what biotic and abiotic factors of environment might be causally associated with the incidence of anthrax mortalities. A systematic examination of the development of today's conceptual model of anthrax epidemiology in livestock and wildlife identifies some of the questions left unanswered. The distillate is then brought to the epidemiologist's work bench as a set of a priori hypotheses for testing in a Poisson regression model. Results indicate that species which browse at 1 to 3 meters have higher mortality rates than do other species of ungulates in the KNP, as do animals near to soil with high calcium and alkaline pH. The genetic diversity of anthrax in the KNP was characterized using a Multi-Locus VNTR Analysis. Ninety-two isolates were analyzed and mapped. Three epidemiological clustering methods were employed to examine genotype group clustering in time and space. The environmental characteristics were then compared for the genotype groups using a non-parametric analysis of variance. Finally, anthrax genotype groups were introduced as factors in the environmental model to determine the effect anthrax mortalities attributable to genotype group. A higher rate of mortality and a more stringent requirement for calcium for one anthrax genotype group relative to the other reveals two mechanisms by which one group may have been limited in its global distribution.

ISBN

9780599372719

Pages

138

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