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Chagas disease in the Andean region

The main vector in the Andean region is R. prolixus, principally in Venezuela and Colombia where it is mainly associated with the foothills of the Andes and adjacent plains (Llanos). R. prolixus is a close relative of the Amazon species R. robustus,9394 and it seems probable that R. prolixus represents a lineage that adapted to exploit drier environments north of the Amazon, thereby predisposing it to be an efficient invader of domestic environments. However, unlike T. infestans, R. prolixus has widespread sylvatic foci that pose the threat of reinvasion of houses postintervention; this was demonstrated by a population genetics study comparing domestic and sylvatic samples in Venezuela40 and by the identification of palm trees as a risk factor to domestic infestations.13 However, previous studies have suggested that the risk of invasion by sylvatic R. prolixus is unlikely.7,95 T. dimidia- ta is implicated in transmission in Colombia and Ecuador. However, there is strong evidence to suggest that T. dimidiata in Ecuador was introduced from mid-Central America in association with human migration patterns.96,97 Therefore, it may represent a more domiciliated population with fewer sylvatic refuges and better prospects for control.

R. ecuadoriensis is an important vector implicated in transmission in Ecuador and northern Peru.18,98 Like R. prolixus, it maintains sylvatic populations in palm trees that pose the risk of reinvasion after the control of domestic populations.19 The Andean initiative (Colombia, Ecuador, Peru, and Venezuela) was inaugurated in 1997. This program, like the Central American countries, has more complications than the Southern Cone initiative because there are more vector species involved which maintain sylvatic habitats and pose the threat of reinvasion post control.94

 
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