Risk of Trypanosoma cruzi I (Kinetoplastida: Trypanosomatidae) transmission by Panstrongylus geniculatus (Hemiptera: Reduviidae) in Caracas (Metropolitan District) and neighboring States, Venezuela

The collection of Panstrongylus geniculatus bugs by inhabitants of dwellings in Caracas city (Metropolitan District) and in the<br>neighboring Miranda and Vargas Sates, Venezuela, allowed for the gathering of data on the potential role of this sylvatic triatomine bug as a<br>vector of Chagas disease in this area. The natural infection by Trypanosoma cruzi was recorded by examining fresh and stained faeces of the<br>bugs. Additionally, a random amplification of polymorphic DNA technique for parasite identification and group typing was employed. A dot-<br>ELISA test was used to identify the gut content of the triatomine bugs with the aim of assessing and quantifying the vector–human contact.<br>Sixty-seven specimens (76.1%) were positive to T. cruzi (identified as T. cruzi I) and 60.2% (53/88) gave a positive reaction to the human<br>antiserum. The human blood-positive samples included mixed blood meals with domestic animals (dog, pig and cow) (9.4%) and with mouse<br>(3.8%). The overall Human Blood Index, measured as the percentage of bugs whose gut contents reacted with human antiserum on the total<br>numbers of bugs that reacted with all the antisera tested, was 98.1%. Almost 41% of the bugs that had fed on humans were also positive for<br>T. cruzi. These data show that the feeding of P. geniculatus on humans does not seem to be accidental and that its rate of infection by T. cruzi<br>is high in this area which is not regarded as endemic for Chagas disease by the National Control Programme. This situation is particularly<br>striking because it occurs in and around Caracas, the capital city, where 20% of the whole population of Venezuela live, human migrations<br>from endemic areas are continuous, people in the crowded shantytown as well as people living in high-quality country houses are equally at<br>risk and the epidemiological cycle Didelphis marsupialis/Rattus rattus–P. geniculatus–human does appear to occur successfully.<br>q 2005 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved