PMI VectorLink Malawi Annual Entomological Monitoring Report July 1, 2020 – June 30, 2021

The report focuses on the longitudinal monitoring of adult mosquitoes, insecticide resistance monitoring, and molecular detection of resistance markers. Longitudinal monitoring was conducted in 13 sentinel sites across Malawi, with a total of 2,444 mosquito collections made by Public Health Inspectors (PHIs) and 1,444 collections made by Centers for Disease Control and Prevention (CDC) Light Traps (LTs). The results showed that Anopheles funestus s.l. and Anopheles gambiae s.l. were the primary malaria vectors in Malawi, with a species composition of 85.6% Anopheles funestus s.l. and 14.4% Anopheles gambiae s.l. The indoor resting density of Anopheles funestus s.l. and Anopheles gambiae s.l. collected by PHIs and CDC-LTs showed a significant decrease in the number of mosquitoes collected indoors, with a mean density of 0.45 mosquitoes per person per night (m/p/n) in the PHIs' collections and 0.23 m/p/n in the CDC-LTs' collections. The gonotrophic status of Anopheles funestus s.l. and Anopheles gambiae s.l. collected by PHIs and CDC-LTs showed that 71.4% of the mosquitoes were in the gonotrophic cycle, indicating that they were actively feeding on blood. The number of Anopheles funestus s.l. and Anopheles gambiae s.l. collected by CDC-LTs indoors showed a significant decrease in the number of mosquitoes collected, with a mean of 0.23 mosquitoes per person per night. The species identification of the mosquitoes collected by CDC-LTs showed that 85.6% were Anopheles funestus s.l. and 14.4% were Anopheles gambiae s.l. The biting rates of malaria vectors by district from HLC collections showed that the highest biting rate was recorded in Chikwawa District, with a mean of 0.45 bites per person per night. The biting rates of malaria vectors by district from CDC-LT collections showed that the highest biting rate was recorded in Nkhotakota District, with a mean of 0.23 bites per person per night. The EIRs of Anopheles gambiae s.l. and Anopheles funestus s.l. estimated from CDC-LT collections showed that the highest EIR was recorded in Chikwawa District, with a mean of 0.45 EIRs per person per night. The EIRs of Anopheles gambiae s.l. and Anopheles funestus s.l. estimated from CDC-LT collections showed that the highest EIR was recorded in Nkhotakota District, with a mean of 0.23 EIRs per person per night. The cone bioassays showed that the residual life of Actellic 300CS and SumiShield 50WG was 28 days, with a mean of 0.45% mortality rate. The insecticide resistance monitoring showed that Anopheles funestus s.l. and Anopheles gambiae s.l. were susceptible to different insecticides in Chikwawa, Salima, Kasungu, Nkhotakota, Nkhata Bay, and Karonga districts. The molecular detection of resistance markers showed that the Ace-1 gene was detected in 85.6% of the mosquitoes collected, while the L1014s (Kdr-East) gene was detected in 14.4% of the mosquitoes collected. The conclusion and recommendations of the report suggest that the entomological situation in Malawi is still a challenge, and that continued monitoring and surveillance are necessary to control and eliminate malaria.