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Center for Nonlinear Studies |
Foot-and-Mouth Disease (FMD) is a highly infectious illness of livestock with economic devastating consequences. We used data from the 2001 FMD epidemic in Uruguay to retrospectively explore for clustering of infections. By identifying clusters, we can look for specific risk factors that may help or hinder the epidemic. The disease location and time of infection were analyzed for the 11 weeks of the epidemic. This included 250 counties (of which 160 were infected). We analyzed the impact of human population density and road density on the spread of the disease. without and with control for human mobility-related factors (human population and road densities). Between the second and the sixth week, a principal disease cluster was observed in 33 contiguous counties (p<0.01). Two secondary clusters, located at >100 km from each other, were also observed (p<0.01). The test that controlled for human population density identified 2 non-contiguous clusters (p<0.01). Human mobility related factors autocorrelated with the spread of the disease. Removal of human population/road densities eliminated 94% of the counties included in the principal disease cluster. Statistically significant correlations (p<0.05) were observed in the first 3 epidemic weeks between road density and the growth rate and showed a decreasing trend in the latter weeks of the epidemic. I will describe a method that potentially can predict the population at risk in future FMD epidemics by looking at correlations with road density.