Interruption of Chagas' disease transmission through vector elimination

The evolution of Chagas disease (American Trypanosomiasis) control after 90 years since Carlos Chagas discovery

“…Where vector control has been satisfactorily implemented in these countries, acute cases of Chagas disease are no longer seen, and serology of young children (born since the launch of the control campaigns) shows very low rates of infection (Dias 1993a, Schmunis et al 1996, WHO 1997. In addition, the prevalence of T. cruzi infection is also decreasing amongst blood donors and women of child-bearing age, bringing corresponding reductions in the risk of transfusional and congenital transmission (Dias 1997).…”

“…In the case of highly domestic species of Triatominae, such as T. infestans in Southern Cone countries, new infestations arise primarily through passive transport of bugs in the clothes and belongings of people travelling from infested to non-infested dwellings (Schofield 1988, Schofield & Dias 1998. Consequently, the broad international strategy (PAHO 1993, Schmunis et al 1996 is to eliminate all domestic foci of T. infestans throughout the region in order to eliminate the possibility of passive transport of bugs from one region to another. In the case of species that retain silvatic ecotopes however, complete elimination is impossible, so that greater emphasis is placed on adequate surveillance, selective retreatment of new infestations, and progressive improvement of rural housing , Briceño-León 1993.…”

Identification and characterization of microsatellite markers in the Chagas disease vector Triatoma dimidiata

“…While the domestic species R. prolixus has been reported to support higher transmission rates to humans and is therefore considered to be a more important disease vector (Ponce, 1999;Tabaru et al, 1999), T. dimidiata is a much greater challenge to control because of its adaptation to both domestic and peri-domestic habitats. Vector control programs in South America have proven highly successful at reducing both home infestation rates and the incidence of new infections in affected areas (Schmunis et al, 1996). Unfortunately, reinfestation rates among treated houses have ranged from 3 to 88%, up to 7 years post spraying (Gurtler et al, 1994;Cecere et al, 1997;Dujardin et al, 1997;Rojas de Arias et al, 1999).…”

Wild Triatoma infestans, a potential threat that needs to be monitored

“…The maximum estimated distribution range of T. infestans, reached during the 1970s, covered the 12 most populated states of Brazil and vast areas of Bolivia, Southern Peru, Chile, Northern Argentina, Paraguay and Uruguay; current estimates show that the distribution of the vector has been reduced by over 80%, but T. infestans foci persist in the highland valleys of Bolivia and in the Gran Chaco Region (Schofield et al 2006). When the Southern Cone Initiative was launched, in 1991, its expected success relied on some peculiar traits of the vector, in particular its lack of insecticide resistance and its almost exclusively domestic nature, as wild populations had only been detected in the highland valley of Cochabamba, in Central Bolivia (Schmunis et al 1996). This latter characteristic, which in principle precluded the recolonisation of treated areas by insects from sylvatic environments, was a pivotal argument for undertaking large-scale control campaigns.…”