Dispersion of Lutzomyia longipalpis in the Chaco province, Argentina.

ENRIQUE ALEJANDRO SZELAG; MATÍAS ARIEL PARRAS; JUAN RAMÓN ROSA; OSCAR DANIEL SALOMÓN

Puerto Iguazú

Simposio; 8th International Symposium on Phlebotomine Sandflies; 2014

Instituto Nacional de Medicina Tropical - Ministerio de salud de la Nación

In Argentina Lutzomyia longipalpis, the main vector of Leishmaniainfantum, was recorded for the first time in 2004 in Formosa province.In the following years, the vector spread to the south and west of thecountry being recorded in the provinces of Misiones (2006),Corrientes (2009), Chaco, Entre Ríos (2010) and Salta (2013). Giventhis fact, the aim of this work was monitoring the spread of Lu.longipalpis in a receptive area of Visceral Leishmaniasis (VL)transmission, in the Chaco province. Captures of Phlebotominae weremade in the city of Resistencia (27°27´S 58°59'W), based on astratified systematic sampling method. From November 2010 to May2012, four strata were sampled once every season, except in winter.The samples were selected by listing and numbering theneighborhoods of each stratum and randomly, selecting 12neighborhood per season. In each neighborhood, the house consideredthe ?worst case epidemiological scenario? was selected as sample site.At each sample site, insects were captured by light CDC traps locatedat 1.5 m, above the animal shelter (kennel, henhouse, etc.) in thecourtyard of the house, during one single night (from 17.00 to 9.00 h).Urban localities near Resistencia were also selected as sentinel sitessampled one per season, to monitor any eventual spread fromResistencia. These sentinel sites included the villages of MargaritaBelén (27°15'S- 58°58'W), Isla del Cerrito (27º17'S- 58°37'W) andBarrio de los Pescadores (27°27'S- 58°51'W).During the study period,14 out of 85 traps installed had at least one phlebotomine, obtaining atotal of 38 Phlebotominae distributed in three locations: Resistencia,Margarita Belen and Barrio de Pescadores. The species recorded wereLu. longipalpis (13.2%), Migonemyia migonei (15.8%), Nyssomyianeivai (39.5%) and cortelezzii complex (31.6%), represented byEvandromyia sallesi and Ev. cortelezzii. In this monitoring Lu.longipalpis was absent in the city of Resistencia, and its presence wasrestricted to Barrio de los Pescadores, the closest area to the city ofCorrientes (with confirmed presence of the vector, VL human andcanine cases). In conclusion, this monitoring of Lu. longipalpisshowed that the incipient colonization of the VL vector observed in2010 with captures of low relative abundance in the city ofResistencia, was not followed by continuous installation of vectorpopulations and expansion of their spatial distribution as in otherurban centers of Argentina.