Visceral Leishmaniasis in Southern Brazil: an overview of current epidemiology.

Visceral leishmaniasis (VL), caused by the protozoan parasite Leishmania (Leishmania) infantum, is transmitted in Brazil through the bites of female phlebotomine sandflies. Until 2008, no cases of autochthonous VL transmission were reported in the southern Brazilian states of Paraná (PR), Santa Catarina (SC), and Rio Grande do Sul (RS). The first case of canine VL (CVL) in RS was reported in 2008, followed by that of human VL (HVL) in 2009. Since then, CVL and HVL cases have emerged in 12 and five additional municipalities in the RS, respectively. In SC, CVL was first reported in Santa Catarina Island in 2010 and is now present in 44 of 89 localities. By 2014, CVL had appeared in western SC, with new cases reported in the midwestern and southern areas in 2021and 2024, respectively. Between 2017 and 2022, five autochthonous HVL cases were diagnosed in Florianópolis. In the PR, CVL was first reported in Foz do Iguaçu in 2012, followed by HVL in 2015. Although Lutzomyia longipalpis, the primary vector of L. infantum in Brazil, has been found in certain municipalities of RS and PR, it has not been reported in other endemic or vulnerable areas of RS and SC. This suggests that other sandfly species may also contribute to disease transmission. This highlights the urgent need for research on the diversity of hosts, vectors, and parasite strains, along with enhanced epidemiological surveillance to clarify the transmission dynamics of VL in these regions.