Biology and Ethology of Triatoma Dimidiata (Latreille, 1811). III. Habitat and blood sources1

Abstract
Of 3459 specimens of Triatoma dimidiata found in and around 198 houses in an endemic Chagas' disease area in Costa Rica, most of those captured indoors were concentrated near the beds. In the periphery of the houses these insects were more common in stacks of firewood; they were also found in firewood being carried inside. Within a radius of 1000 m from the nearest house, T. dimidiata was also found in hollow trees, mainly those inhabited by opossums. Precipitin tests revealed that human blood was the most common in the gut content of the bugs (63.7% for those captured indoors and 21.9% for those outdoors), followed in descending order by blood from dog, rat (or mouse), chicken, and opossum. This does not indicate a preference for man but rather that he is the most available host. Mobility of T. dimidiata is indicated by the fact that human blood was found in those captured outside which presumably came from indoor populations. Blood from other hosts including cold-blooded animals, either alone or in combination, was also identified in some T. dimidiata. One bug contained blood from 6 different hosts. Rat and opossum bloods were more common in T. cruzi-positive insects whereas blood of chicken and toad were more frequent in the negative groups. The concurrent finding of human and or domestic animal and opossum blood in some T. dimidiata, plus the natural association of the marsupial and T. dimidiata in Costa Rica, is strong evidence of a link between the wild and the domestic cycles of T. cruzi.

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