Sierra Leone

According to Sierra Leone’s Malaria Indicator Survey (SLMIS) 2016, malaria is endemic in the country with the stable and perennial transmission. Malaria prevalence is 40% among children age 6-59 months and is the main cause of morbidity and mortality among children under 5 years. Malaria prevalence is two times higher in rural areas (49%) than in urban ones (25%).

Insecticide-treated bednets (ITNs) are distributed to children between 12 and 59 months of age upon successful completion of PENTA3 immunization, and to pregnant women during the first contact for antenatal care. The first mass distribution of ITNs took place in 2006 in Bo and Pujehun districts. The same year, a countrywide mass ITN distribution for children under 1 year of age occurred alongside a measles vaccine campaign. Mass distribution of ITNs was subsequently conducted in 2010, 2014, and 2017. These mass campaigns, together with other distribution channels, helped increase the ownership of ITNs from 37% in 2008 (SLDHS, 2008) to 60% in 2016 (SLMIS, 2016). In 2019, 67.9% of the households owned at least one ITN in Sierra Leone (DHS, 2019). The insecticide resistance monitoring conducted in 2018-2019 indicated strong resistance of the main malaria vector Anopheles gambiae in Sierra Leone to pyrethroids.

After pre-exposure to piperonyl butoxide (PBO), the mortality rate observed for both deltamethrin and permethrin increased in the four sentinel districts but was below the 90% cut-off point for confirmed resistance indicating that a monooxygenase-based resistance mechanism is partially involved, but is not fully responsible for the pyrethroid resistance observed. Based on this finding, the NMCP is planning an ITN mass campaign for May 2020. All ITNs distributed will contain either the pyrethroid deltamethrin or permethrin plus the synergist PBO. This will be the first time in Sierra Leone that a nationwide mass distribution campaign of ITNs with the PBO synergist will be undertaken.

In 2019, VectorLink Sierra Leone supported the NMCP in the maintenance and management of the insectary established in Makeni (Bombali District) which was established in 2018. VectorLink continued to maintain the susceptible Kisumu strain of An. gambiae. VectorLink also supported the monitoring of vector bionomics, providing information on vector density, distribution, and behaviors. The susceptibility of An. gambiae s.l. to the insecticides used in public health was assessed, and these data guided the development of the Insecticide Resistance Monitoring and Management Plan (IRMMP), the Integrated Vector Management Policy (IVMP), and Strategic plans. The information also helped the NMCP select the appropriate ITNs for distribution during the 2020 mass campaign. In 2020, the project will continue to provide technical and financial assistance to the NMCP to conduct malaria vector bionomics monitoring in 15 sentinel sites in five districts and insecticide resistance of An. gambiae s.l. (see Table 1 in Section 3.1). In 2020, VectorLink will continue to support the NMCP in holding quarterly meetings of the VCTWG and semi-annual meetings of the IVM National Steering Committee to review entomological data for decision making on vector control interventions for malaria and other vector-borne diseases

The information collected on vector density, seasonal distribution, behavior, and infectivity will be used to determine the optimal time to do IRS and it will serve as baseline data for assessing IRS impact. In addition, VectorLink will support ITN durability monitoring after the 2020 ITN mass campaign and will start the baseline data collection for the assessment of the impact of the co-deployment of PBO nets and IRS  in Sierra-Leone.

VectorLink Sierra Leone has the following objectives for 2021 (Year 4):


  • Support the NMCP in spraying an estimated 147,992 eligible structures in 12 chiefdoms in Bombali District and 16 chiefdoms in Bo District, using SumiShield TM
  • Ensure that the spraying is of high quality, achieves at least 85% spray coverage, and protects an estimated population of 706,357.
  • Build capacity at the national, district, and chiefdom levels to manage IRS operations, including planning, spraying, and monitoring and evaluation (M&E).
  • Engage District Health Management Teams (DHMT) and Peripheral Health Unit (PHU) staff in the planning, implementation, and supervision of IRS in the two districts.
  • Establish a system to promote gender equality and female empowerment by recruiting women to fill at least 30% of the IRS seasonal worker positions. VectorLink will encourage the health zone selection committees to achieve the mandatory quota.
  • Coordinate community mobilization activities in collaboration with PHU and local authorities to raise awareness and achieve high community acceptance of IRS.
  • Conduct high-quality M&E of IRS, including daily performance monitoring during the IRS campaign, to ensure the achievement of the objectives and targets assigned.
  • Prepare a Supplemental Environmental Assessment (SEA) to submit to PMI at least two months before the IRS campaign begins.
  • Under the leadership of the project Environmental Compliance Officer (ECO), provide capacity building and work in collaboration with the NMCP Directorate of Environmental Health in the Ministry of Environment to conduct environmental inspections.

Entomological Monitoring Activities

  • Continue to maintain functional insectaries in Makeni and Freetown with the gambiae Kisumu strain available at all times and annual colony verification.
  • Continue measuring the susceptibility of the main malaria vector, gambiae s.l., to (in order of priority) deltamethrin, permethrin, clothianidin, chlorfenapyr, alpha-cypermethrin, , and pirimiphos-methyl. Susceptibility of An. gambiae s.l. from Bo, Bombali, Kono, Port Loko, and Karene districts will be tested.
  • Measure the intensity of resistance to pyrethroids, and perform synergist assays, where appropriate.
  • Subcontract with the Centre for Research in Infectious Diseases (CRID), a regional laboratory in Cameroon or other suitable laboratories to use polymerase chain reaction (PCR) to process mosquitoes to identify samples to the species level, and use PCR/enzyme-linked immunosorbent assay (ELISA) to test sample mosquitoes for infectivity and determination of blood meal origin.
  • Subcontract with CRID or other suitable laboratory to use PCR to identify the mechanism associated with the resistance observed (knockdown resistance (kdr) and acetylcholinesterase 1 (Ace-1) mutations).
  • Work with NMCP and Universities to find a suitable laboratory partner in Sierra Leone and begin the capacity building process in 2022 in order to conduct in-country laboratory analysis of samples collected.
  • Monitor the density, biting rate, behavior, and parity of malaria vectors in 16 sentinel sites.

ITN Activities

  • Continue to support the NMCP in conducting the second round of ITN durability monitoring covering the two types of ITNs distributed in 2020.

Assessment of the Co-deployment of PBO Nets and IRS

  • Continue to support the NMCP in collecting baseline and post-IRS data to assess the impact of PBO nets and IRS co-deployment.

National-level Support:

  • Continue to build the capacity of the NMCP and district health staff to use entomological data for decision making.
  • Continue to support the NMCP in holding quarterly meetings of the VCTWG and semi-annual meetings of the IVM National Steering Committee.
  • Continue to provide technical support to the NMCP and other stakeholders for data review for IRS insecticide selection in 2022.
  • Support NMCP to review the Insecticide Resistance Monitoring and Management Plan (IRMMP)