Geographical heterogeneity in the analysis of factors associated with leprosy in an endemic area of Brazil: Are we eliminating the disease?

Abstract

Background: The leprosy transmission chain is very complex and, in order to intervene in this transmission, more must be known about the factors linked to falling ill. There are doubts as to the influence of population size, population density and the disease's magnitude in detection rate trends. This paper aimed to identify factors associated with detection of leprosy in an endemic municipality of Rio de Janeiro State, Brazil. Methods: This ecological study in Duque de Caxias municipality, Rio de Janeiro State, Brazil, used neighbourhoods (bairros) as the unit of analysis. Selecting new cases of leprosy detected from 1998 to 2006, the analysis examined clinical, socioeconomic and service variables using a Poisson log-Normal model. Results: In the municipality overall, 2572 new cases were detected, a rate of 3.70 cases/10,000 inhabitants. The results describe a heterogeneous distribution of cases and rates in the municipality. The final model displayed a significant association with indeterminate clinical form (β=2.599), proportion of homes with running water (β=-2.334) and presence of a decentralised health care unit (β=0.524). Conclusion: Although the results indicate progress towards elimination of the disease in the municipality, high rates continue to be detected in municipal sub-regions. The following question can thus be posed: over how wide a geographical area could the disease be thoroughly eliminated, given this heterogeneity within a small municipality?