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Home arrow Economics arrow American Trypanosomiasis Chagas Disease, Second Edition: One Hundred Years of Research


Does vector transmission occur outside human dwellings?

The existence of vector-borne transmission outside dwellings is virtually undocumented; however, it may exist. Only one report suggests this kind of transmission. In the northern part of the state of Amazonas, three cases of chronic chagasic cardiopathy have been reported in patients who were bitten several times by triato- mine bugs in their camping huts while gathering pia ava fibers.105 Moreover, some species are aggressive, and one of the authors has personally experienced severe attacks by T. guasayana and T. sordida outdoors at dusk in the Gran Chaco region, Bolivia. For the Indians of the Sierra Nevada in Colombia, the economy is based on agriculture located in different climatic zones. They travel into the mountains to reach their crops and commonly stay in camps. In addition to the classic transmission related to colonization of dwellings by R. prolixus and T. dimidiata, the practice of camping results in people being exposed to triatomine bites independent of human dwellings (Dib, personal communication). Moreover, a Yucatan farmer reported to us that he had collected wild T. dimidiata specimens during a 1-month camping trip in the forest where he hunted; every day at dusk he was attacked by about five triatomines when he was resting in his hammock. Another interesting case occurred during light trap collection of triatomines in Southern Ecuador106: a male Rhodnius ecuadoriensis, attracted by the light, remained a long moment on the leg of a person sitting approximately 6 m from the light trap.

Indirectly, the identification of blood meals taken on humans by specimens of T. infestans, including nymphs, caught in a wild environment in Bolivia shows that the risk exists.107-109 Lastly, human blood meals in T. sanguisuga captured in a wild environment were also reported in Louisiana.110 These experiences show that travelers in the Americas should be informed that camping in the forest or in other uninhabited environments where natural populations of triatomines exist is dangerous; self-protection is indispensable during the night.

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