Spatial distribution of triatomines (Reduviidae: Triatominae) in urban areas of the city of Salvador, Bahia, Brazil

Abstract

Environmental changes have a strong influence on the emergence and/or reemergence of infectious diseases. The city of Salvador, Brazil--currently the focus of a housing boom linked to massive deforestation--is an example in point as the destruction of the remaining areas of the Atlantic Forest around the city has led to an increased risk for Chagas disease. Human domiciles have been invaded by the triatomine vectors of Trypansoma cruzi, the flagellate protozoan causing Chagas disease, a problem of particular concern in urban/suburban areas of the city such as the Patamares sector in the north-east, where numbers of both the vector and human cases of the disease have increased lately. To control and prevent further deterioration of the situation, the control programme for Chagas disease, developed by the Bahia Center for Zoonosis Control, has divided the area into a grid of designated surveillance units (ZIs) that are subjected to vector examination. In six out of 98 of these ZIs, 988 triatomes were collected and georeferenced during the 3-year period between 2006 and 2009. The hottest months, that are also generally the driest, showed the highest numbers of triatomines with Triatoma tibiamaculata being the predominant species (98.3%) with Panstrongylus geniculatus present only occasionally (0.6%). Fifty-four percent of all triatomines captured were found inside the homes, and 48.6% out of 479 individuals in the affected ZIs selected for analysis tested positive for T. cruzi infection. The study presented here is a pioneering initiative to map the spatial distribution of triatomines based on geographical information systems with the additional aim of contributing to an expanded knowledge-base about T. cruzi and its vectors in urban areas and raise public health awareness of the risks involved.