Attractive targeted sugar baits (ATSB) have shown potential in reducing malaria incidence in a cluster-randomized controlled trial conducted in Western Province, Zambia. The study, published in the Malaria Journal, evaluated the efficacy of ATSB stations in reducing malaria transmission in an area with seasonal malaria transmission, where the dominant vector species is Anopheles funestus.
Trial Design and Methodology
The two-arm cluster-randomized controlled trial was conducted across multiple districts in Western Province, Zambia. Seventy clusters were retained for the trial, using a 'fried egg' design to prevent contamination. Participants were recruited into two seasonal cohorts from November-December 2021, and November-December 2022. The primary outcome was the incidence of symptomatic malaria in children aged 12 months to 14 years, defined by fever and a positive rapid diagnostic test (RDT) result.
In intervention clusters, two ATSB stations (Sarabi version 1.2) were installed on each eligible structure of consenting households. The standard of care included insecticide-treated nets (ITN) and indoor residual spraying (IRS). Statistical analysis was performed using a generalized linear model (GLM) framework with Poisson likelihood and log link function.
Key Findings
The study found a non-significant reduction in malaria incidence in the ATSB intervention arm compared to the control arm. The primary unadjusted intention-to-treat (ITT) analysis showed no statistically significant difference in clinical malaria incidence between the two arms. Similarly, the secondary outcome of infection prevalence did not show a significant difference between the groups.
Intervention Details
ATSB stations were installed on exterior walls of structures at 1.8 meters above ground level, under eaves where possible. Trained community members monitored the stations every two months, replacing damaged or missing stations. The ATSB stations used in the trial contained a bait formulation designed to attract and kill malaria vectors.
Vector Control Context
The trial site included areas with both IRS and ITN interventions. IRS was conducted using clothianidin-deltamethrin. ITN distributions provided deltamethrin-impregnated nets and pyrethroid piperonyl butoxide (PBO) impregnated nets to households.
Study Limitations
The authors note that the trial results should be interpreted considering the existing malaria control interventions in the study area, such as ITNs and IRS. The lack of a significant reduction in malaria incidence may be due to the already high coverage of these interventions.
Implications for Malaria Control
While the study did not demonstrate a statistically significant reduction in malaria incidence, the use of ATSB could still be a valuable supplementary tool in integrated malaria control strategies. Further research is needed to optimize the deployment and formulation of ATSB, and to evaluate its effectiveness in different epidemiological settings. The study highlights the importance of considering local vector behavior and environmental factors when implementing malaria control interventions.
