| From 1991 to 2004, bovine tuberculosis (Mycobacterium bovis, BTB) moved north and increased in prevalence in the African buffalo ( Syncerus caffer) population of the Kruger National Park, South Africa. I use this epidemic as a case study to understand how host population structure affects disease dynamics. Radio-tracking data indicated that all sex and age groups moved between herds, but males over eight years old had higher mortality and dispersal rates than any other sex or age category. BTB appeared to have only minor effects upon survival. Models incorporating these data suggest that the success of vaccination programs will depend strongly upon the duration that a vaccine grants protection, which is currently unknown. Even with a lifelong vaccine, however, eradication is unlikely unless vaccination is combined with other control strategies.; To analyze the radio-tracking and association data, I proposed a new metric of association, the fission decision index (FDI) that significantly reduces the biases that exist in traditional association analyses in fission-fusion societies. Adult female and juvenile buffalo made non-random fission decisions while adult male choices were indistinguishable from a random coin toss. Incorporating the association data into a dynamic social network model suggested that the dynamic nature of the network has a strong influence on disease dynamics, particularly for diseases with shorter infectious periods. Buffalo herds were more tightly associated in 2002 than 2003, perhaps due to drier conditions in 2003 prompting additional movement that would facilitate the spread of disease among herds.; Using a metapopulation model, I illustrate how the group-level metric, R*, which is the average number of groups infected by the initial group, is a better predictor of disease invasion than the traditional individual-level R0 in structured host populations. R* is a function of group size, movement rate, infection rate, and length of the infectious period. Chronic diseases allow for more host mixing between groups; thus they 'perceive' a more well-mixed host population. As a result, chronic diseases are more likely to invade structured populations than acute diseases, given the same R0, and it is more important to incorporate the spatial structure of the host population for acute diseases than chronic diseases. |
