Adaptive intervention strategies for malaria vector control in western Kenya: a cluster, sequential,...

Area of Science:

• Malariology and Vector Control
• Public Health Interventions
• Epidemiology

Background:

• High malaria burden in Africa necessitates improved, locally adapted vector control tools.
• Existing interventions like pyrethroid-only long-lasting insecticidal nets (LLINs) show limitations in some areas.

Purpose of the Study:

• To develop and evaluate adaptive malaria vector control strategies tailored to local eco-epidemiological contexts in Kenya.
• To compare the efficacy of different LLIN types and indoor residual spraying (IRS) regimens.

Main Methods:

• A two-stage, cluster, sequential, multiple-assignment, randomised trial involving 84 clusters in western Kenya.
• Stage 1 interventions included standard LLINs, piperonyl butoxide-treated LLINs (PBO nets), or standard LLINs + annual IRS.
• Non-responding clusters were re-randomised in Stage 2 to evaluate supplemental microbial larviciding or enhanced IRS strategies.

Main Results:

• PBO nets significantly reduced malaria incidence compared to standard LLINs at 1-12 months.
• Standard LLINs + annual IRS was more effective than standard LLINs alone.
• In Stage 2, enhanced IRS combined with LLINs showed greater efficacy than biannual IRS; PBO nets + IRS outperformed PBO nets + larviciding.

Conclusions:

• Replacing conventional pyrethroid-only LLINs with PBO nets is recommended as a primary malaria control strategy.
• Adaptive strategies, including annual IRS or microbial larviciding, can further reduce malaria burden in moderate-to-high-risk areas.