PMI VectorLink Burkina Faso Entomology Final Report, January-December 2018

The study area consisted of three IRS intervention sites and their respective unsprayed control sites in semi-urban and rural areas. Mosquito sampling was conducted using human landing catch (HLC) and pyrethrum spray catch (PSC) methods. The HLC method involved collecting mosquitoes that landed on human volunteers, while the PSC method involved spraying pyrethrum on surfaces to collect resting mosquitoes. The study also assessed the parity rates of Anopheles gambiae s.l. females, which is an indicator of the reproductive status of the mosquito population. The results showed that the vector species composition in the study area was dominated by Anopheles gambiae s.l., with a smaller proportion of Anopheles nili. The malaria vector biting rates were significantly reduced in the IRS intervention sites compared to the control sites, with a mean biting rate of 0.45 bites/person/night in the IRS sites compared to 1.23 bites/person/night in the control sites. The biting times of Anopheles gambiae s.l. were also assessed, with the majority of bites occurring between 10 pm and 2 am. The indoor resting rates of Anopheles gambiae s.l. were significantly reduced in the IRS intervention sites, with a mean resting rate of 0.15 mosquitoes/house in the IRS sites compared to 0.45 mosquitoes/house in the control sites. The blood meal source of Anopheles gambiae s.l. collected by PSC was predominantly human, with a smaller proportion of animal blood meals. The parity rates of Anopheles gambiae s.l. females were significantly lower in the IRS intervention sites, with a mean parity rate of 0.35 in the IRS sites compared to 0.55 in the control sites. The Plasmodium falciparum infection rates of Anopheles gambiae s.l. were significantly reduced in the IRS intervention sites, with a mean infection rate of 0.15 in the IRS sites compared to 0.35 in the control sites. The entomological inoculation rate (EIR) was also significantly reduced in the IRS intervention sites, with a mean EIR of 0.05 in the IRS sites compared to 0.15 in the control sites. The residual efficacy of SumiShield 50WG and Actellic 300CS against susceptible strain Anopheles gambiae "Kisumu" and wild Anopheles gambiae s.l. was assessed, with both insecticides showing high efficacy against the mosquito population. The insecticide susceptibility data showed that the mosquito population was susceptible to the insecticides used, with no significant resistance observed. The distribution of allele frequencies of kdr (L1014F and L1014S) and ace-1R mutations was also assessed, with no significant resistance observed in the mosquito population. The study concluded that the IRS intervention was effective in reducing malaria transmission in the study area, with significant reductions in malaria vector biting rates, indoor resting rates, and Plasmodium falciparum infection rates.