Changing epidemiology of visceral leishmaniasis in northeastern Brazil: a 25-year follow-up of an urban outbreak.

Background: Visceral leishmaniasis (VL) continues to be a deadly parasitic disease in Brazil but the epidemiology has changed. The objective of this study was to assess the evolution of urban VL in the city of Natal, Brazil, over the past 25 y.

Methods: A retrospective study of human VL was performed, considering reported cases over the past 25 y in Natal. Analyses considered the spatial distribution of VL cases, human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) co-infection, Leishmania infantum infection in dogs, density of the insect vector (Lutzomyia longipalpis) and socio-economic factors.

Results: Paralleling migration of the population, VL cases changed from mostly rural to predominantly urban regions. The incidence of human VL was highest during the initial years (1990-1994) of our study. Human VL was positively associated with a high density of L. longipalpis, a high prevalence of canine L. infantum infection and HIV/AIDS co-infection. The average age at diagnosis increased over prior years and males were more frequently affected. The overall fatality rate was 6%. Socio-economic variables indicative of poverty were associated with a greater incidence of VL and clusters of VL.

Conclusion: VL has become endemic in Natal. The disease is associated with poverty and male gender. Surprisingly, there has been an increase in the age at diagnosis.