Feeding rates of malaria vectors from a prototype attractive sugar bait station in Western Province, Zambia: results of an entomological validation study

Chanda, Javan, Wagman, Joseph, Chanda, Benjamin, Kaniki, Tresford, Ng’andu, Mirabelle, Muyabe, Rayford, Mwenya, Mwansa, Sakala, Jimmy, Miller, John, Mwaanga, Gift, Simubali, Limonty, Mburu, Monicah Mirai, Simulundu, Edgar, Mungo, Alice, Fraser, Keith, Mwandigha, Lazaro, Ashton, Ruth, Yukich, Joshua, Harris, Angela F., Burkot, Thomas R., Orange, Erica, Littrell, Megan, and Entwistle, Julian (2023) Feeding rates of malaria vectors from a prototype attractive sugar bait station in Western Province, Zambia: results of an entomological validation study. Malaria Journal, 22. 70.

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Background: Attractive targeted sugar bait (ATSB) stations are a promising new approach to malaria vector control that could compliment current tools by exploiting the natural sugar feeding behaviors of mosquitoes. Recent proof of concept work with a prototype ATSB® Sarabi Bait Station (Westham Co., Hod-Hasharon, Israel) has demonstrated high feeding rates and significant reductions in vector density, human biting rate, and overall entomological inoculation rate for Anopheles gambiae sensu lato (s.l.) in the tropical savannah of western Mali. The study reported here was conducted in the more temperate, rainier region of Western Province, Zambia and was designed to confirm the primary vector species in region and to estimate corresponding rates of feeding from prototype attractive sugar bait (ASB) Sarabi Bait Stations.

Methods: The product evaluated was the Sarabi v1.1.1 ASB station, which did not include insecticide but did include 0.8% uranine as a dye allowing for the detection, using UV fluorescence light microscopy, of mosquitoes that have acquired a sugar meal from the ASB. A two-phase, crossover study design was conducted in 10 village-based clusters in Western Province, Zambia. One study arm initially received 2 ASB stations per eligible structure while the other initially received 3. Primary mosquito sampling occurred via indoor and outdoor CDC Miniature UV Light Trap collection from March 01 through April 09, 2021 (Phase 1) and from April 19 to May 28, 2021 (Phase 2).

Results: The dominant vector in the study area is Anopheles funestus s.l., which was the most abundant species group collected (31% of all Anophelines; 45,038/144,5550), had the highest sporozoite rate (3.16%; 66 positives out of 2,090 tested), and accounted for 94.3% (66/70) of all sporozoite positive specimens. Of those An. funestus specimens further identified to species, 97.2% (2,090/2,150) were An. funestus sensu stricto (s.s.). Anopheles gambiae s.l. (96.8% of which were Anopheles arabiensis) is a likely secondary vector and Anopheles squamosus may play a minor role in transmission. Overall, 21.6% (9,218/42,587) of An. funestus specimens and 10.4% (201/1,940) of An. gambiae specimens collected were positive for uranine, translating into an estimated daily feeding rate of 8.9% [7.7–9.9%] for An. funestus (inter-cluster range of 5.5% to 12.7%) and 3.9% [3.3–4.7%] for An. gambiae (inter-cluster range of 1.0–5.2%). Feeding rates were no different among mosquitoes collected indoors or outdoors, or among mosquitoes from clusters with 2 or 3 ASBs per eligible structure. Similarly, there were no correlations observed between feeding rates and the average number of ASB stations per hectare or with weekly rainfall amounts.

Conclusions: Anopheles funestus and An. gambiae vector populations in Western Province, Zambia readily fed from the prototype Sarabi v1.1.1 ASB sugar bait station. Observed feeding rates are in line with those thought to be required for ATSB stations to achieve reductions in malaria transmission when used in combination with conventional control methods (IRS or LLIN). These results supported the decision to implement a large-scale, epidemiological cluster randomized controlled trial of ATSB in Zambia, deploying 2 ATSB stations per eligible structure.

Item ID: 78765
Item Type: Article (Research - C1)
ISSN: 1475-2875
Copyright Information: © The Author(s) 2023. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
Date Deposited: 06 Jun 2023 05:59
FoR Codes: 42 HEALTH SCIENCES > 4206 Public health > 420699 Public health not elsewhere classified @ 50%
31 BIOLOGICAL SCIENCES > 3109 Zoology > 310913 Invertebrate biology @ 50%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1806 Terrestrial systems and management > 180602 Control of pests, diseases and exotic species in terrestrial environments @ 100%
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