Risco ecoepidemiológico do vírus do nilo ocidental no nordeste brasileiro

Abstract

In 1999, West Nile virus (WNV) reached the New World and gained increasing attention due to a high incidence of neuroinvasive symptoms and became a significant public health concern in the United States. In the following years, the virus spread to Latin America, causing sporadic cases and small outbreaks, apparently due to inadequate reporting and confusion with other arboviruses. The first evidence of enzootic circulation in Brazil dates back to 2009, from the state of Mato Grosso do Sul. Today, human cases are reported in five states, with most of them occurring in the northeast of the country, in the state of Piauí. With the aim of reducing detection time and increasing the effectiveness of disease surveillance to prevent future outbreaks, an ecological risk approach was used to determine risk levels for the districts in the region. In determining these risk levels, which range from 0 to 5, the potential occurrence of two mosquito vectors (Culex quinquefasciatus and Aedes albopictus) and the virus was assessed using predictive models based on environmental factors as well as the presence of migratory bird concentration areas and confirmed pathogen circulation in the districts. A total of 27 communities with confirmed circulation and 142 adjacent communities were counted, 221 with all necessary conditions for virus introduction and spread (mosquitoes, migratory birds, and environmental conditions), 607 with two of these factors, 684 with only one, and 194 without any of these factors. The average risk at state level was higher in Bahia and Sergipe and lower in Maranhão and Pernambuco. Based on this data, it was possible to propose priority areas and pathogens for surveillance.