Preferred resting surfaces of dominant malaria vectors inside different house types in rural south-eastern Tanzania

Msugupakulya, B. J., Kaindoa, E. W., Ngowo, H. S. , Kihonda, J. M., Kahamba, N. F., Msaky, D. S., Matoke-Muhia, D., Tungu, P. K. and Okumu, F. O. (2020) Preferred resting surfaces of dominant malaria vectors inside different house types in rural south-eastern Tanzania. Malaria Journal, 19, 22. (doi: 10.1186/s12936-020-3108-0) (PMID:31941508) (PMCID:PMC6964015)

[img]
Preview
Text
208839.pdf - Published Version
Available under License Creative Commons Attribution.

3MB

Abstract

Background: Malaria control in Africa relies extensively on indoor residual spraying (IRS) and insecticide-treated nets (ITNs). IRS typically targets mosquitoes resting on walls, and in few cases, roofs and ceilings, using contact insecticides. Unfortunately, little attention is paid to where malaria vectors actually rest indoors, and how such knowledge could be used to improve IRS. This study investigated preferred resting surfaces of two major malaria vectors, Anopheles funestus and Anopheles arabiensis, inside four common house types in rural south-eastern Tanzania. Methods: The assessment was done inside 80 houses including: 20 with thatched roofs and mud walls, 20 with thatched roofs and un-plastered brick walls, 20 with metal roofs and un-plastered brick walls, and 20 with metal roofs and plastered brick walls, across four villages. In each house, resting mosquitoes were sampled in mornings (6 a.m.–8 a.m.), evenings (6 p.m.–8 p.m.) and at night (11 p.m.–12.00 a.m.) using Prokopack aspirators from multiple surfaces (walls, undersides of roofs, floors, furniture, utensils, clothing, curtains and bed nets). Results: Overall, only 26% of An. funestus and 18% of An. arabiensis were found on walls. In grass-thatched houses, 33–55% of An. funestus and 43–50% of An. arabiensis rested under roofs, while in metal-roofed houses, only 16–20% of An. funestus and 8–30% of An. arabiensis rested under roofs. Considering all data together, approximately 40% of mosquitoes rested on surfaces not typically targeted by IRS, i.e. floors, furniture, utensils, clothing and bed nets. These proportions were particularly high in metal-roofed houses (47–53% of An. funestus; 60–66% of An. arabiensis). Conclusion: While IRS typically uses contact insecticides to target adult mosquitoes on walls, and occasionally roofs and ceilings, significant proportions of vectors rest on surfaces not usually sprayed. This gap exceeds one-third of malaria mosquitoes in grass-thatched houses, and can reach two-thirds in metal-roofed houses. Where field operations exclude roofs during IRS, the gaps can be much greater. In conclusion, there is need for locally-obtained data on mosquito resting behaviours and how these influence the overall impact and costs of IRS. This study also emphasizes the need for alternative approaches, e.g. house screening, which broadly tackle mosquitoes beyond areas reachable by IRS and ITNs.

Item Type:Articles
Additional Information:This study was supported by Ifakara Health Institute (Training and Capacity Building Department) as part of the Msc Studentship awarded to BJM, and Howard Hughes Medical Institute (HHMI)—Gates International Research Scholarship awarded to FOO (Grant No. OPP1099295).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Ngowo, Halfan and Okumu, Dr Fredros
Creator Roles:
Okumu, F.Conceptualization
Authors: Msugupakulya, B. J., Kaindoa, E. W., Ngowo, H. S., Kihonda, J. M., Kahamba, N. F., Msaky, D. S., Matoke-Muhia, D., Tungu, P. K., and Okumu, F. O.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Malaria Journal
Publisher:BMC
ISSN:1475-2875
ISSN (Online):1475-2875
Copyright Holders:Copyright © 2020 The Author(s)
First Published:First published in Malaria Journal 19:22
Publisher Policy:Reproduced under a Creative Commons License

University Staff: Request a correction | Enlighten Editors: Update this record