Spatial assessment of the effects of deforestation, wildfire, and drought on the incidence of rabies in herbivores in the state of Maranhão, Brazil

Abstract

This study aimed to analyze the effects of the frequency and intensity of fires, as well as variations in the land surface covered by water, on the incidence of animal rabies. It sought to contribute to the improvement of control and prevention strategies for the disease. The analysis was based on cases of rabies reported in cattle and horses in the state of Maranhão, from 2006 to 2022, using the state's geographical microregions as study units. The relationship between the variables was analyzed using Poisson regression and the Local Bivariate Moran's Index. The results indicated a higher incidence of animal rabies in the northern part of the state, where there are lower livestock densities. It was observed that an increase in fire frequency and greater deforestation are associated with a reduction in rabies incidence, suggesting that the impact of these variables on the habitat of the main vectors has a positive effect on the migratory population dynamics of these animals and on the spread of the rabies virus. Additionally, the loss of water surface showed a positive correlation with the virus incidence, indicating that drought might be related to internal migration, closer proximity, and increased interaction among the disease's transmitter populations. The study proved effective in estimating the risk of occurrence and spread of rabies in the state, recommending the inclusion of measures to mitigate the environmental impacts caused by fires in rabies control and prevention strategies.