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Improving houses in the Bolivian Chaco increases effectiveness of residual insecticide spraying against infestation with Triatoma infestans, vector of Chagas disease

Gonçalves, Raquel, Landivar, Daniel, Liendo, Edson Grover Sañez, Fernandez, Janet Mamani, Ismail, Hanafy, Paine, Mark ORCID: https://orcid.org/0000-0003-2061-7713, Courtenay, Orin and Bern, Caryn (2021) 'Improving houses in the Bolivian Chaco increases effectiveness of residual insecticide spraying against infestation with Triatoma infestans, vector of Chagas disease'. Tropical Medicine & International Health, Vol 26, Issue 9, pp. 1127-1138.

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Abstract

Objective
Failure to control domestic Triatoma infestans in the Chaco is attributed to vulnerable adobe construction, which provides vector refuges and diminishes insecticide contact. We conducted a pilot to test the impact of housing improvement plus indoor residual spraying (IRS) on house infestation and vector abundance in a rural community in the Bolivian Chaco.

Methods
The intervention included three arms: housing improvement + IRS [HI], assisted IRS [AS] in which the team helped to clear the house pre-IRS and routine IRS [RS]. HI used locally available materials, traditional construction techniques and community participation. Vector parameters were assessed by Timed Manual Capture for 2 person-hours per house at baseline and medians of 114, 173, 314, 389 and 445 days post-IRS-1. A second IRS round was applied at a median of 314 days post-IRS-1.

Results
Post-intervention infestation indices and abundance fell in all three arms. The mean odds of infestation was 0.29 (95% CL 0.124, 0.684) in the HI relative to the RS arm. No difference was observed between AS and RS. Vector abundance was reduced by a mean 44% (24.8, 58.0) in HI compared to RS, with no difference between AS and RS. Median delivered insecticide concentrations per house were lower than the target of 50 mg/m2 in >90% of houses in all arms.

Conclusion
Housing improvement using local materials and community participation is a promising strategy to improve IRS effectiveness in the Bolivian Chaco. A larger trial is needed to quantify the impact on reinfestation over time.

Item Type: Article
Subjects: QX Parasitology > Insects. Other Parasites > QX 503 Hemiptera (e.g., Bedbugs)
WA Public Health > Health Problems of Special Population Groups > WA 395 Health in developing countries
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 705 Trypanosomiasis
Faculty: Department: Biological Sciences > Vector Biology Department
Digital Object Identifer (DOI): https://doi.org/10.1111/tmi.13640
Depositing User: Mel Finley
Date Deposited: 01 Jul 2021 14:52
Last Modified: 13 Sep 2021 10:09
URI: https://archive.lstmed.ac.uk/id/eprint/18136

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