Journal Article

Eave ribbons treated with transfluthrin can protect both users and non-users against malaria vectors

Kifungo, Khamis, Ngowo, Halfan S., Okumu, Fredros O., Mwanga, Emmanuel P., Mmbando, Arnold S., Ogoma, Sheila B., Finda, Marceline F., Monroe, April C., Stica, Caleb, Mrosso, Paul C., Mapua, Salum A., Kafwenji, Andrew

2019

Overview

Background Eave ribbons treated with spatial repellents effectively prevent human exposure to outdoor-biting and indoor-biting malaria mosquitoes, and could constitute a scalable and low-cost supplement to current interventions, such as insecticide-treated nets (ITNs). This study measured protection afforded by transfluthrin-treated eave ribbons to users (personal and communal protection) and non-users (only communal protection), and whether introducing mosquito traps as additional intervention influenced these benefits. Methods Five experimental huts were constructed inside a 110 m long, screened tunnel, in which 1000 Anopheles arabiensis were released nightly. Eave ribbons treated with 0.25 g/m 2 transfluthrin were fitted to 0, 1, 2, 3, 4 or 5 huts, achieving 0, 20, 40, 60, 80 and 100% coverage, respectively. Volunteers sat near each hut and collected mosquitoes attempting to bite them from 6 to 10 p.m. (outdoor-biting), then went indoors to sleep under untreated bed nets, beside which CDC-light traps collected mosquitoes from 10 p.m. to 6 a.m. (indoor-biting). Caged mosquitoes kept inside the huts were monitored for 24 h-mortality. Separately, eave ribbons, UV–LED mosquito traps (Mosclean) or both the ribbons and traps were fitted, each time leaving the central hut unfitted to represent non-user households and assess communal protection. Biting risk was measured concurrently in all huts, before and after introducing interventions. Results Transfluthrin-treated eave ribbons provided 83% and 62% protection indoors and outdoors respectively to users, plus 57% and 48% protection indoors and outdoors to the non-user. Protection for users remained constant, but protection for non-users increased with eave ribbons coverage, peaking once 80% of huts were fitted. Mortality of mosquitoes caged inside huts with eave ribbons was 100%. The UV–LED traps increased indoor exposure to users and non-users, but marginally reduced outdoor-biting. Combining the traps and eave ribbons did not improve user protection relative to eave ribbons alone. Conclusion Transfluthrin-treated eave ribbons protect both users and non-users against malaria mosquitoes indoors and outdoors. The mosquito-killing property of transfluthrin can magnify the communal benefits by limiting unwanted diversion to non-users, but should be validated in field trials against pyrethroid-resistant vectors. Benefits of the UV–LED traps as an intervention alone or alongside eave ribbons were however undetectable in this study. These findings extend the evidence that transfluthrin-treated eave ribbons could complement ITNs.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Adult / Animals / Anopheles / Anopheles arabiensis / Aquatic insects / Biomedical and Life Sciences / Biomedicine / Biting / Culicidae / Cyclopropanes / Eave ribbons / Entomology / Fluorobenzenes / Households / Human diseases / Humans / Ifakara Health Institute / Indoor environments / Infectious Diseases / Insect Bites and Stings - prevention & control / Insect Repellents / Insecticides / LEDs / Light traps / Malaria / Malaria - prevention & control / Male / Microbiology / Mortality / Mosquito Control - methods / Mosquito Vectors / Mosquitoes / Nets / Outdoors / Parasitology / Pest control / Prevention / Protection / Public Health / Pyrethroids / Repellents / Retirement benefits / Risk factors / Sleep / Tanzania / Transfluthrin / Tropical Medicine / Tunnels / Ultraviolet radiation / Vector-borne diseases / Vectors / Young Adult