A New Test of a Theory about Old Mosquitoes. Issue 3 (March 2021)

• Record Type: Journal Article
• Authors: Smith, David L.; Musiime, Alex K.; Maxwell, Kilama; Lindsay, Steven W.; Kiware, Samson
• Is Part Of: Trends in parasitology. Volume 37:Issue 3(2021)
• Page Start: 185
• Page End: 194
• Publication Date: 2021-03
• Subjects: malaria -- dynamics and control -- vector control -- mosquito ecology; Parasitology -- Periodicals; Parasitology -- Periodicals; Biology -- Periodicals; Parasitology; Biology; Parasitologie -- Périodiques; Online resources; 571.999
• DOI: 10.1016/j.pt.2020.10.011
• Languages: English
• ISSNs: 1471-4922

Abstract

Abstract : In vector control, it is widely accepted that killing adult mosquitoes would sharply reduce the proportion of old mosquitoes and cause the greatest changes to malaria transmission. The principle is based on a mathematical model of the sporozoite rate (the proportion of infective mosquitoes) that emphasized changes in mosquito age. Killing adult mosquitoes also reduces mosquito population densities, which are directly proportional to human biting rates (the number of bites, per person, per day). Effect sizes of vector control can be compared using sporozoite rates and human biting rates, which are commonly measured. We argue that human biting rates convey more useful information for planning, monitoring and evaluating vector control, and operational research should focus on understanding mosquito ecology. Highlights: Killing adult mosquitoes with vector control is highly effective because it reduces transmission in several ways: (i) mosquitoes are less likely to become infected and less likely to survive long enough for parasites to become infective, which affects the sporozoite rate (SR); (ii) adult mosquitoes lay fewer eggs, so fewer adults emerge, and each emerging mosquito gives fewer bites, which reduces the human-biting rate (HBR). A simple test of the importance of age versus density involves comparing changes in the HBR with changes in the SR. In some cases, variability in transmission intensity and the success of malaria control is clearly due to variability or changes in the HBR. The effects of vector control on the HBR are unpredictable across ecological settings. To reduce uncertainty and improve the outcomes of vector control, entomological surveillance should prioritize measuring the HBR.