Visceral leishmaniasis in Southern Rio de Janeiro State and the risk of propagation to São Paulo State, Brazil.

Visceral leishmaniasis (VL), also known as American VL, or neotropical kala-azar, is an epidemic zooanthroponosis endemic to Brazil. It affects both rural and peri-urban areas, and can also spread into urban areas. The causative agent is Leishmania infantum chagasi, and the principal vector is the sand fly species Lutzomyia longipalpis. Domestic dogs are the main host for the insect vector, and once infected can transmit the protozoan infection to other canids and humans(1). Human and canine VL propagated by L. longipalpis has recently been observed in Rio de Janeiro City, the Middle Paraíba Valley and the Costa Verde Fluminense. This has exposed the contiguous Paraíba Valley (Vale do Paraiba) and the North Coast (Litoral Norte), in the neighboring São Paulo State, to new infections. Although a similar situation occurred in the 1990s in western São Paulo State, during which the infection traversed highways and railways connecting the region to Mato Grosso do Sul State, the latter was already endemic for VL. The current complexity of urban VL transmission poses new challenges, and there is an urgent need for new strategies to control the spread of infection. The increased circulation of human populations and infected dogs, and greater distribution of the sand fly vector, which is also influenced by human activities, need to be considered(1).