Eco-Epidemiology of Visceral Leishmaniasis in Argentina

SALOMÓN OD; FERNANDEZ MS; SANTINI MS; ACARDI SA; GOULD IT; LIOTTA DJ; QUINTANA MG

Congreso; 5º World Congress on Leishmaniasis, Worldleish 5; 2013

From 1925 to 1989, 14 cases of Visceral Leishmaniasis (VL) were reported in Argentina. These cases were scattered through the area of cutaneous leishmaniasis without records of competent vectors. Phlebotomine surveillance was intensified in border areas since the year 2000 due to the reports of urban VL in Brazil and Paraguay. Lutzomyia longipalpis was found spatially clustered in Clorinda (Formosa) in 2004, the first urban report of the vector of VL in Argentina despite of previous captures in the same area; however, the spatial distribution of canine cases (VLc) was more related to pet transit patterns than to vector abundance. The first autochthonous human case, concurrent with VLc and vectors, was reported during 2006 in Posadas (Misiones). Since then 113 human cases were reported (Misiones: 94, Corrientes: 10, Santiago del Estero: 6, Salta: 3) with a fatality rate of 10.6% (less than 8% in youngsters). Social and commercial pet-related networks dispersed VLc in almost all the country. Lu longipalpis dispersion was evaluated each summer, up to 2011 the vector reaches the northern border of Misiones, Corrientes (since 2008), Chaco (Resistencia), Entre Rios (Chajari), and the Republic of Uruguay (Salto, Bella Unión). In Santiago del Estero and Salta VL in humans and dogs were related with a different transmission scenario, at least in former focus associated with Migonemyia migonei as a putative vector. The localities are stratified according to the risk and control measures consistent with WHO recommendations are proposed. Lu. longipalpis in the city of Posadas was distributed in 41.5% (2007) and 31.0% (2009) of the sampled households, with 8.3 (SD 40.6) individuals per trap-night in 2007 and 22.3 (SD 93.2)individuals per trap-night in 2009. The sites with higher vector abundances were clustered in patches that increased in size and number from 2007 to 2009, supporting a meta-population structure hypothesis. The higher vector abundances were associated with areas with higher tree and bush cover (macrohabitat) and the peridomiciles with chickens, trees, and unused materials (microhabitat). The distribution of Lu. longipalpis by hour, the human-dog attractiveness, and the impact of current anti-vectorial insecticide measures were evaluated. Leishmania infantum genotypification was achieved from humans, dogs and vectors by PCR-RFLP and sequencing-based confirmation assays. Risk maps at different scales are currently developed.