Spatial and statistical methodologies to determine the distribution of dengue in Brazilian municipalities and relate incidence with the Health Vulnerability Index

Dengue fever is among the most important emerging infectious diseases in the world, and in recent years it has been a source of public concern for the public health control systems of many tropical and subtropical countries. Thus, the purpose of this study was to apply spatial and statistical methodologies to analyze the geographic distribution of dengue and to relate its incidence to the Health Vulnerability Index (HVI), an indicator that integrates different socioeconomic variables to estimate the degree of health vulnerability in different Brazilian cities. The cases of dengue, incidence rates and Bayesian incidence rates were determined using census tracts covering a period of 3 years in a city with socioeconomic and administrative characteristics typical of Brazilian municipalities. Distribution plots, descriptive statistics, kernel density maps, test of global and local spatial autocorrelation and Spearman correlation were used. No association was found between the incidence of dengue and the HVI. Conversely, statistically significant high-incidence clusters were found over the 3 years in an area identified as having lower health vulnerability. The finding that HVI was not a good indicator of dengue in the city studied may be explained by the complexity of the disease. Administrative and financial problems in the municipalities, environmental factors, cultural changes and the emergence of new serotypes are other factors that hinder the understanding and control of the disease. However, the spatial and statistical methodologies used here are suitable and useful tools for the accurate understanding of dengue and other infectious epidemiological processes.