Abstract
Background Triatoma infestans —the principal vector of the infection that causes Chagas disease— defies elimination efforts in the Gran Chaco region. This study identifies the types of human-made or -used structures that are key sources of these bugs in the initial stages of house reinfestation after an insecticide spraying campaign.Methodology and Principal FindingsWe measured demographic and blood-feeding parameters at two geographic scales in 11 rural communities in Figueroa, northwest Argentina. Of 1,297 sites searched in spring, 279 (21.5%) were infested. Bug abundance per site and female fecundity differed significantly among habitat types (ecotopes) and were highly aggregated. Domiciles (human sleeping quarters) had maximum infestation prevalence (38.7%), human-feeding bugs and total egg production, with submaximal values for other demographic and blood-feeding attributes. Taken collectively peridomestic sites were three times more often infested than domiciles. Chicken coops had greater bug abundance, blood-feeding rates, engorgement status, and female fecundity than pig and goat corrals. The host-feeding patterns were spatially structured yet there was strong evidence of active dispersal of late-stage bugs between ecotopes. Two flight indices predicted that female fliers were more likely to originate from kitchens and domiciles, rejecting our initial hypothesis that goat and pig corrals would dominate.Conclusions and SignificanceChicken coops and domiciles were key source habitats fueling rapid house reinfestation. Focusing control efforts on ecotopes with human-fed bugs (domiciles, storerooms, goat corrals) would neither eliminate the substantial contributions to bug population growth from kitchens, chicken coops, and pig corrals nor stop dispersal of adult female bugs from kitchens. Rather, comprehensive control of the linked network of ecotopes is required to prevent feeding on humans, bug population growth, and bug dispersal simultaneously. Our study illustrates a demographic approach that may be applied to other regions and triatomine species for the design of innovative, improved vector control strategies.
Highlights
Of the approximately 140 species of Triatominae (Heteroptera: Reduviidae) currently recognized, Triatoma infestans (Klug) expresses the extreme of an evolutionary trend toward domesticity [1,2]
Our study illustrates a demographic approach that may be applied to other regions and triatomine species for the design of innovative, improved vector control strategies
The current study aims to fill this knowledge gap and identify the types ofdomestic structures that function as key sources of bugs at the initial stages of house reinfestation after an insecticide spraying campaign
Summary
Of the approximately 140 species of Triatominae (Heteroptera: Reduviidae) currently recognized, Triatoma infestans (Klug) expresses the extreme of an evolutionary trend toward domesticity [1,2]. This adaptation and epidemiological significance as the most important vector of human Chagas disease justified targeting T. infestans for elimination in the southern cone countries of South America since 1991 [3]. Inadequate housing and subsistence rural economies facilitate the persistence of T. infestans in the Gran Chaco. Triatoma infestans —the principal vector of the infection that causes Chagas disease— defies elimination efforts in the Gran Chaco region. This study identifies the types of human-made or -used structures that are key sources of these bugs in the initial stages of house reinfestation after an insecticide spraying campaign
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