The rural-urban gradient of house infestation with Triatoma infestans in an endemic municipality of the Argentine Chaco region

GASPE, MARÍA S.; FERNANDEZ, MARÍA DEL PILAR; ENRIQUEZ, GUSTAVO; RODRÍGUEZ PLANES, LUCÍA INÉS; GÜRTLER, RICARDO E; CARDINAL, MARTA V.; MACCHIAVERNA, NATALIA

Baltimore

Encuentro; Sixty Sixth Annual Meeting; 2017

ASTMH

The Gran Chaco ecoregion is one of the main hotspots of neglected tropical diseases in the Americas, including Chagas disease. The occurrence of the major vector Triatoma infestans has historically been linked to poor rural housing, but (peri)urban infestations have been increasingly reported over recent decades. We conducted a cross-sectional survey of house infestation with T. infestans in all rural, periurban and urban sections of Avia Terai, an endemic municipality in the Argentine Chaco, as part of a 3-year intervention program combining insecticide spraying with educational aspects and community mobilization. The district had been sprayed with pyrethroid insecticides by Chagas vector control technicians 2-5 years before our survey. The baseline prevalence of house infestation decreased along a rural-to-urban gradient ranging from 43% (among 275 rural houses inspected), 16% (367 periurban houses) to 14% (402 urban houses), as determined by manual searches with a dislodging aerosol conducted over October 2015-March 2016. Bug colonies were found in nearly all infested houses. Most infestations occurred in peridomestic structures housing chickens and other domestic animals. Domestic infestations displayed a similar rural-to-urban gradient from 9%, 4% to 2%. Urban foci were spread through the town, and periurban infestations largely differed among neighborhoods (range, 0-59%). The village-specific prevalence rates of house infestation recorded in rural areas before control interventions (2011-2013) and in 2015 were similar. These results attest the fast recovery of triatomine populations after traditional insecticide spraying campaigns that did not include sustained vector surveillance and control afterwards. The large indices of house infestation found in periurban and urban habitats of traditionally endemic regions reveal the need of revising current vector control practices in affected areas of the Gran Chaco.