Observing the distribution of mosquito bites on humans to inform personal protection measures against malaria and dengue vectors

Mponzi, W. P. et al. (2022) Observing the distribution of mosquito bites on humans to inform personal protection measures against malaria and dengue vectors. PLoS ONE, 17(7), e0271833. (doi: 10.1371/journal.pone.0271833) (PMID:35877666) (PMCID:PMC9312397)

Abstract

Background: Understanding mosquito biting behaviours is important for designing and evaluating protection methods against nuisance biting and mosquito-borne diseases (e.g. dengue, malaria and zika). We investigated the preferred biting sites by Aedes aegypti and Anopheles arabiensis on adult volunteers in standing or sleeping positions; and estimated the theoretical protection limits affordable from protective clothing or repellent-treated footwear. Methods: Adult volunteers dressed in shorts and t-shirts were exposed to infection-free laboratory-reared mosquitoes inside screened chambers from 6am to noon (for day-biting Ae. aegypti) or 6pm to midnight (night-biting An. arabiensis). Attempted bites on different body parts were recorded. Comparative observations were made on same volunteers while wearing sandals treated with transfluthrin, a vapour-phase pyrethroid that kills and repels mosquitoes. Results: An. arabiensis bites were mainly on the lower limbs of standing volunteers (95.9% of bites below the knees) but evenly-distributed over all exposed body surfaces when the volunteers were on sleeping positions (only 28.8% bites below knees). Ae. aegypti bites were slightly concentrated on lower limbs of standing volunteers (47.7% below knees), but evenly-distributed on sleeping volunteers (23.3% below knees). Wearing protective clothing that leave only hands and head uncovered (e.g. socks + trousers + long-sleeved shirts) could theoretically prevent 78–83% of bites during sleeping, and at least 90% of bites during non-sleeping hours. If the feet are also exposed, protection declines to as low as 36.3% against Anopheles. The experiments showed that transfluthrin-treated sandals reduced An. arabiensis by 54–86% and Ae. aegypti by 32–39%, but did not change overall distributions of bites. Conclusion: Biting by An. arabiensis and Ae. aegypti occur mainly on the lower limbs, though this proclivity is less pronounced in the Aedes species. However, when hosts are on sleeping positions, biting by both species is more evenly-distributed over the exposed body surfaces. High personal protection might be achieved by simply wearing long-sleeved clothing, though protection against Anopheles particularly requires covering of feet and lower legs. The transfluthrin-treated footwear can reduce biting risk, especially by An. arabiensis. These findings could inform the design and use of personal protection tools (both insecticidal and non-insecticidal) against mosquitoes and mosquito-borne diseases.

• Item Type: Articles
• Additional Information: This study was funded by United states Agency for International development (USAID) (Grant number AID-OAA-F-16-00093) awarded to FO. Also this study was supported by Wellcome Trust Intermediate Fellowship in Public Health and Tropical medicine (Grant Number: WT 102350/Z/13) and Howard Hughes Medical Institute (HHMI) and Gates foundation (Grant: 0PP1099295) awarded to FOO. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ngowo, Halfan and Okumu, Professor Fredros

Creator Roles

Ngowo, H. S.: Formal analysis, Methodology, Writing – review and editing
Okumu, F. O.: Conceptualization, Formal analysis, Methodology, Supervision, Writing – review and editing

• Authors: Mponzi, W. P., Swai, J. K., Kaindoa, E. W., Kifungo, K., Eiras, A. E., Batista, E. P. A., Matowo, N. S., Sangoro, P. O., Finda, M. F., Mmbando, A. S., Gavana, T., Ngowo, H. S., and Okumu, F. O.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: PLoS ONE
• Publisher: Public Library of Science
• ISSN: 1932-6203
• ISSN (Online): 1932-6203
• Copyright Holders: Copyright © 2022 Mponzi et al.
• First Published: First published in PLoS ONE 17(7): e0271833
• Publisher Policy: Reproduced under a Creative Commons License