Field evaluation of personal protection methods against outdoor-biting mosquitoes in Lao PDR

Tangena, Julie-Anne A.; Thammavong, Phoutmany; Chonephetsarath, Somsanith; Logan, James G.; Brey, Paul T.; Lindsay, Steve W.

Abstract

Background: Protecting people outdoors against mosquito-borne diseases is a major challenge. Here we compared commercially available personal protection methods to identify the most effective method for outdoor use in northern Lao PDR. Methods: From June to August 2016 the protective efficacy of treatments were compared in a secondary forest during the afternoon and a village during the evening. Comparisons were made using a replicated Latin square design between: (i) short permethrin-treated overalls; (ii) long permethrin-treated overalls; (iii) short untreated overalls with para-menthane-3,8-diol (PMD) applied topically; (iv) short permethrin-treated overalls plus PMD applied topically; (v) short untreated overalls with metofluthrin coils in a metal casing worn on a belt; and (vi) long untreated overalls. Short untreated overalls served as the control. Cone tests were conducted on the treated and untreated fabric before and after field experiments. A questionnaire survey was used to measure social acceptability. Results: Mosquito coils in a metal casing worn on a belt resulted in 92.3% (95% confidence interval, CI: 88.9–94.6%). landing protection from female mosquitoes in the afternoon and 68.8% (95% CI: 41.7–83.3%) protection in the evening compared to short untreated clothing. PMD was protective both when combined with short permethrin-treated overalls (afternoon, 68.2%, 95% CI: 52.6–78.7%; evening, 52.3%, 95% CI: 33.8–65.7%) and when used in combination with short untreated overalls (afternoon, 55.0%, 95% CI: 41.7–65.2%; evening, 25.2%, 95% CI: 9.4–38.2%). Whilst long permethrin-treated overalls were protective (afternoon, 61.1%, 95% CI: 51.4–68.8%; evening, 43.0%, 95% CI: 25.5–56.4%), short permethrin-treated overalls and long untreated overalls were not. Exposure to new permethrin-treated fabric in cone tests resulted in 25.0% (95% CI, 17.8–32.2%) and 26.2% (95% CI 16.7–35.8%) mortality for susceptible Ae. albopictus and susceptible Ae. aegypti, respectively. There was a loss of efficacy of permethrin-treated clothing after use in the field, with 3 min knockdown rates of Ae. albopictus and 1 h knockdown of Ae. aegypti decreasing over time. Participants considered all treatments acceptable. Conclusions: The portable mosquito coils were highly protective against outdoor biting mosquitoes, although there are safety concerns related to its use. The combination of permethrin-treated clothing and PMD repellent represent an alternative treatment for protection against outdoor-biting mosquitoes.

Citation

Tangena, J. A., Thammavong, P., Chonephetsarath, S., Logan, J. G., Brey, P. T., & Lindsay, S. W. (2018). Field evaluation of personal protection methods against outdoor-biting mosquitoes in Lao PDR. Parasites and Vectors, 11(1), Article 661. https://doi.org/10.1186/s13071-018-3239-0

• Journal Article Type: Article
• Acceptance Date: Nov 28, 2018
• Online Publication Date: Dec 17, 2018
• Publication Date: Dec 17, 2018
• Deposit Date: Jan 3, 2019
• Publicly Available Date: Jan 3, 2019
• Journal: Parasites and Vectors
• Publisher: BioMed Central
• Peer Reviewed: Peer Reviewed
• Volume: 11
• Issue: 1
• Article Number: 661
• DOI: https://doi.org/10.1186/s13071-018-3239-0
• Public URL: https://durham-repository.worktribe.com/output/1340654