Epidemiological surveys confirm an increasing burden of cutaneous leishmaniasis in north-east Brazil

Health service records for north-east Brazil suggest a consistent rise in numbers of cases of cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis over the past decade. In a study site in Pernambuco, prospective, cross-sectional and retrospective epidemiological surveys of infection (a positive Montenegro skin test response) and/or clinical symptoms confirmed a high current force of infection (0.092/year), and an approximately 10-fold increase in transmission during the last 10 years. Cross-sectional analysis indicated that the incidence rate among children (aged less than or equal to 15 years) was lower than that among adult immigrants exposed for similar time periods, but there was no apparent difference in transmission rate according to gender. Coupled with the known behaviour of the local sandfly vector, Lutzomyia whitmani, this suggests that most people are infected outside their houses, rather than either indoors or while visiting remnant rainforest. The estimated proportion of infections which lead to cutaneous lesions (0.81-0.87) is relatively high for L. braziliensis areas. However, an unusually low proportion of clinical infections (0.0042) apparently leads to metastasis.