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Chagas disease in the Amazon region

The Amazon region is vast, extending across much of northwestern Brazil, the Guyanas, northern Bolivia, eastern Peru and Ecuador, and southern Colombia and Venezuela. The region has a high number of sylvatic triatomine species.8,85 However, only the following seven (mostly Rhodnius species) have been implicated in disease transmission: R. prolixus, R. pictipes, R. robustus, R. stali, P. geniculatus, P. herreri, and T. maculata. There are also a plethora of reservoir hosts (e.g., marsupials, bats, rodents, edentates, carnivores, and primates). In the Amazon, the observed tendency is that infestation by triatomine species is occasional and sporadic. Most Amazon species seem to be constrained from readily exploiting domestic environments by preadaptation to humid environments.

Human activities that negatively impact the natural ecology of triatomines species, such as deforestation, are likely to drive adaptation to the domestic environment.85

There is a diverse range of T. cruzi strains reported from the Amazon from TcI to TcV. Predominantly TcI and TcIII circulate,55 and both have been associated with human infections along with TcIV.42,47 There are many reports of acute cases of disease in humans,86 but chronic forms of the disease are considered to be relatively rare in the region. As described by Miles et al., , currently the main type of transmission cycle in the Amazon region is enzootic (i.e., no/few domestic colonies of triatomines exist), but infrequent, sporadic cases of Chagas disease may occur due to bugs sporadically flying into houses and infecting people or contaminating food. There are numerous reports of small epidemics in the Brazilian

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Amazon, mainly attributed to oral transmission. ,

Often oral contamination involves palm-dwelling species (most likely Rhodnius species) that are accidentally collected along with palm fruits, such as acai, and subsequently pressed to make juice. The most recent outbreaks was reported by de Noya and Gonzalez.91 Another paradigm is communities are frequently attacked by R. brethesi when venturing into the forest along the Rio Negro (Brazil, Colombia, and Venezuela) to harvest piassaba palm fibers.86 There are also reports of foci of transmission associated with vector infestation, such as P. geniculatus in the Amazon basin, R. stali in Bolivia, and P. herreri in Peru. An initiative for Chagas disease surveillance and prevention in the Amazon (AMCHA) was officially launched with the backing of Pan American Health Organization (PAHO) in 2004.92

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