Beating the odds: sustained Chagas disease vector control in remote indigenous communities of the Argentine Chaco over a seven-year period.

GASPE MS; PROVECHO YM.; FERNANDEZ MP; VASSENA C; SANTO ORIHUELA PL; GÜRTLER RE

PLOS NEGLECTED TROPICAL DISEASES

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2018 vol. 12 p. 6804 - 6804

1935-2735

Rapid reinfestation of insecticide-treated dwellings hamper the sustained elimination of Triatomainfestans, the main vector of Chagas disease in the Gran Chaco region. We conducteda seven-year longitudinal study including community-wide spraying with pyrethroid insecticidescombined with periodic vector surveillance to investigate the house reinfestation processin connection with baseline pyrethroid resistance, housing quality and householdmobility in a rural section of Pampa del Indio mainly inhabited by deprived indigenous people(Qom).Methodology/Principal findingsDespite evidence of moderate pyrethroid resistance in local T. infestans populations, houseinfestation dropped from 31.9% at baseline to 0.7% at 10 months post-spraying (MPS),with no triatomine found at 59 and 78 MPS. Household-based surveillance corroborated therare occurrence of T. infestans and the house invasion of other four triatomine species. Theannual rates of loss of initially occupied houses and of household mobility were high (4.6±8.0%). Housing improvements did not translate into a significant reduction of mud-walledhouses and refuges for triatomines because most households kept the former dwelling orbuilt new ones with mud walls.Conclusions/SignificanceOur results refute the assumption that vector control actions performed in marginalized communitiesof the Gran Chaco are doomed to fail. The larger-than-expected impacts of theintervention program were likely associated with the combined effects of high-coverage,professional insecticide spraying followed by systematic vector surveillance-and-response,broad geographic coverage creating a buffer zone, frequent housing replacement and residentialmobility. The dynamical interactions among housing quality, mobility and insecticidebasedcontrol largely affect the chances of vector elimination.