The epidemiological behaviour of leprosy in Brazil

BACKGROUNDThe elimination strategy reduced known leprosy prevalence but the detection rate remains high in many countries, including Brazil. The high Brazilian detection rate imposes a limit to the reduction of known prevalence in the short term. The knowledge of time behaviour and spatial distribution of leprosy statistics will contribute to decision making for leprosy control.METHODThe numbers of newly diagnosed leprosy cases by region and year from 1980 to 2004, and prevalent cases from 1990 to 2007 were fitted as a parabolic function of time in negative binomial regression models. To detect areas with increased leprosy detection rates we used spatial scan statistics for cases detected from 2005 to 2007 in the three regions where leprosy is still a public health problem.RESULTSAll detection rate series except the one for the south region showed statistically significant regression coefficients for time and time squared, showing an initial increasing trend. Scan statistics detected 29 statistically significant spatial clusters. These clusters cover 789 municipalities with a total of 51,904 cases detected.CONCLUSIONTime behaviour of the detection rate is probably a result of better access to primary health care. According to spatial scan statistics, Brazil can be divided into highly endemic areas, containing 11.2% of the total Brazilian population, with a mean detection rate in 2007 of 76.4 per 100,000 inhabitants, and areas of much lower endemicity, containing 888% of the population with a mean detection rate of 132. Leprosy is concentrated in a small proportion of the Brazilian population.