1. Impacts of ivermectin mass drug administration for onchocerciasis on mosquito populations of Ogun state, Nigeria.
- Author
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Omitola OO, Umunnakwe CU, Bayegun AA, Anifowose SA, Mogaji HO, Oluwole AS, Odoemene SN, Awolola TS, Osipitan AA, Sam-Wobo SO, and Ekpo UF
- Subjects
- Animals, Anopheles physiology, Culex physiology, Female, Male, Mass Drug Administration, Nigeria, Population Density, Anopheles drug effects, Culex drug effects, Insecticides pharmacology, Ivermectin pharmacology, Mosquito Control methods
- Abstract
Background: The impact of single-dose mass drug administration (MDA) of ivermectin for onchocerciasis on mosquito populations was investigated in Ogun State, Nigeria., Methods: Indoor and outdoor collection of mosquitoes was carried out in two intervention (IC) and two control communities (CC) at three different periods: pre-MDA (baseline), 2-3 days after MDA and 13-14 days after MDA. The density and parity rate of female Anopheles and Culex mosquitoes were determined and compared. Environmental and climatic data of study locations were obtained to perform generalized linear model analysis., Results: A total of 1399 female mosquitoes were collected, including 1227 Anopheles and 172 Culex mosquitoes. There was a similar magnitude of reduction in the indoor density of Anopheles by 29% in the IC and CC 2-3 days post-MDA but the reduction in indoor parity rate was significantly higher (p = 0.021) in the IC, reducing by more than 50%. In the IC, observation of a significant reduction at 2-3 days post-MDA was consistent for both the indoor density (1.43 to 1.02) and indoor parity rate (95.35% to 44.26%) of Anopheles mosquitoes. The indoor parity rate of Anopheles remained significantly reduced (75.86%) 13-14 post-MDA. On the other hand, the indoor density of Culex increased from 0.07 to 0.10 at 2-3 days post-MDA while the indoor parity rate of Culex did not change. The outdoor density of Anopheles in the IC increased (p = 0.394) from 0.58 to 0.90 at 2-3 days post-MDA; a similar observation was consistent for the outdoor density (2.83 to 3.90) and outdoor parity rate (70.59% to 97.44%) of Culex, while the outdoor parity rate of Anopheles reduced from 85.71 to 66.67% at 2-3 days post-MDA. A generalized linear model showed that ivermectin MDA significantly caused a reduction in both the indoor density (p < 0.001) and indoor parity rate (p = 0.003) of Anopheles in the IC., Conclusion: Ivermectin MDA resulted in the reduction of both the survival and density of Anopheles mosquitoes. This has strong implications for malaria transmission, which depends strongly on vector survival.
- Published
- 2021
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