Evaluating ATSBs for Malaria Reduction in Kenya
- Conditions
- Malaria
- Interventions
- Device: Attractive Targeted Sugar Bait (ATSB)
- Registration Number
- NCT05219565
- Lead Sponsor
- Liverpool School of Tropical Medicine
- Brief Summary
The effectiveness of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) in western Kenya are threatened by insecticide resistance and vector behaviour changes toward early evening and outdoor biting malaria vectors. New tools to control malaria are needed to reduce and even interrupt malaria transmission. Attractive Targeted Sugar Bait (ATSB) is a promising new intervention designed to attract and kill mosquitoes, including those that IRS and LLINs do not effectively target. The ATSB 'bait stations' are A4-sized panels containing thickened fruit syrup laced with a neonicotinoid insecticide, dinotefuran, to attract and kill the foraging vectors. Entomological field trials in western Mali showed that ATSBs successfully reduce mosquito densities and longevity and thus have the potential to reduce malaria transmission. In Kenya, the investigators will conduct an open-label cluster-randomized controlled trial in 80 village clusters (40 per arm) to evaluate the effect of ATSBs on the burden of malaria. During two years, households in half of these village clusters will receive two or three ATSB bait stations per household structure on exterior walls approximately 1.8 meters above the ground. ATSBs will be replaced every six months. The primary outcome will be the incidence of clinical malaria in children aged 1-\<15 years enrolled in a prospective cohort followed monthly for about six months each during a 2-year period. Secondary outcomes include malaria infection prevalence assessed by rapid diagnostic tests through household surveys and the case burden of clinical malaria assessed by passive facility-based and community-based surveillance. The study includes entomological monitoring and nested acceptability, feasibility, and health economics studies. The stand-alone trial in western Kenya is a part of a multi-country ATSB consortium conducting similar trials in Zambia and Mali.
- Detailed Description
The current malaria vector control tools, long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are critically important and have saved many lives. However, their effectiveness in western Kenya is threatened by insecticide resistance and vector behaviour changes toward more early evening and outdoor biting malaria vectors. LLINs and IRS specifically target indoor-biting and indoor-resting mosquitoes. Malaria vectors exhibit different behavioural characteristics that mitigate the effectiveness of vector control strategies. For example, traditionally, An. gambiae s.s. has been regarded as human-biting with late-night indoor-feeding and indoor-resting behaviours, while An. Arabiensis is found more often in drier environments and is more zoophagic with outdoor biting and resting behaviours. Following LLINs and IRS's widespread scale-up, the dominant African vectors' distributions and behaviours changed with An. gambiae s.s. and An. Funestus (also an indoor human biter) diminishing in abundance relative to An. arabiensis. Subsequently, shifts towards earlier evening biting by An. Gambiae s.s. (before people enter houses to sleep under LLINs) and later biting by An. Funestus (biting in the morning after sunrise) are examples of behavioural plasticity enabling these species to avoid contact with the LLIN and IRS insecticides.
There is a need for interventions that supplement and complement LLINs and IRS by killing mosquitoes outside houses using other biologic mechanisms (e.g., targeting sugar feeding behaviour). Furthermore, insecticides are required with novel modes of action that may restore sensitivity to pyrethroids by killing both pyrethroid-resistant and sensitive mosquitoes. Attractive Targeted Sugar Bait (ATSB) (the name was recently changed from Attractive Toxic Sugar Bait to highlight that it targets malaria vectors) is a promising new intervention that potentially fills the need for outdoor interventions with novel killing effects.
ATSB 'bait stations' are A4-sized panels containing thickened fruit syrup laced with a neonicotinoid insecticide (dinotefuran) to attract and kill the foraging vectors. Entomological field trials in Mali showed that ATSBs successfully reduce mosquito densities and longevity and thus have the potential to reduce malaria transmission. Large scale efficacy studies are now needed to establish the efficacy of ATSB for controlling malaria transmission.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 2962
Not provided
Not provided
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description Attractive Targeted Sugar Bait (ATSB) Attractive Targeted Sugar Bait (ATSB) Clusters within the ATSB arm will have 2 ATSBs hung on all eligible structures in the cluster where consent from the corresponding compound has been given.
- Primary Outcome Measures
Name Time Method Clinical malaria Two years The incidence rate of clinical malaria defined as current fever (axillary temperature of ≥37.5°C) or history of fever in last 48 hours and a positive rapid diagnostic test (RDT, pLDH or HRP2), in children aged 1-\<15 years enrolled in the cohort study
- Secondary Outcome Measures
Name Time Method Sporozoite rate Two years Entomological outcomes: Sporozoite rate
Incidence of non-malaria illness (passive surveillance) Two years The incidence rate of non-malaria illness assessed by health-facility and community-based surveillance
Prevalence of non-malaria illness Two years The prevalence of non-malaria illness in cross-sectional household surveys
Markers of insecticide resistance (deltamethrin) Two years Entomological outcome: Proportion of mosquitoes with resistance to deltamethrin among total mosquitoes collected in 4 WHO mosquito tubes in the trial area
AEs Two years Number of adverse events associated with misuse of ATSBs.
Perceptions of ATSBs Two years The proportion of household heads who perceive ATSBs as safe and effective out of all household head who consented to ATSB deployment on their household structures.
Time to first malaria infection by PCR Two years The time to first malaria infection assessed by PCR in children aged 1-\<15 years enrolled in a cohort study
Malaria infection incidence by RDT (pLDH) Two years The incidence rate of malaria infection detected by RDT (pLDH) in children aged 1-\<15 years enrolled in a cohort study
Non-Target Organisms (NTOs) attracted to ATSBs Two years Entomological outcome: Proportion of monitoring visits where NTOs were observed on bait stations
Incidence of malaria illness (passive surveillance) Two years The incidence rate of malaria illness (sick-visit with a positive malaria rapid diagnostic test or microscopy) assessed by health-facility and community-based surveillance
Entomological Inoculation Rate (EIR) Two years Entomological outcome: Entomological Inoculation Rate (EIR)
Complexity of infection (COI) Two years The complexity of (malaria) infection assessed by molecular markers, including, but not limited to, 24-single-nucleotide polymorphisms (24-SNP) barcodes
Household care seeking behavior in the setting of ATSBs Two years The proportion of children aged 1-\<15 years enrolled in a cohort study who sought care for febrile illness
Incidence of non-malaria illness (cohort) Two years The incidence rate of non-malaria illness in children aged 1-\<15 years enrolled in a cohort study
Markers of insecticide resistance (dinotefuran) Two years Entomological outcome: Proportion of mosquitoes with resistance to dinotefuran among total mosquitoes collected in 4 WHO mosquito tubes in the trial area
Markers of insecticide resistance (permethrin) Two years Entomological outcome: Proportion of mosquitoes with resistance to permethrin among total mosquitoes collected in 4 WHO mosquito tubes in the trial area
Antibody concentrations against malaria antigen MSP-1 Two years Antibody concentration against merozoite surface protein-1 (MSP-1) among cohort participants
Antibody concentrations against malaria antigen CSP Two years Antibody concentration against circumsporozoite proteins (CSP) among cohort participants
Malaria vector density Two years Entomological outcome: Malaria vector densities
Malaria infection prevalence by RDT (pLDH) Two years The prevalence of malaria infection detected by RDT (pLDH) in cross-sectional household surveys
Proportion of female anopheles mosquitoes older than three gonotrophic cycles, Two years Entomological outcome: The proportion of female anopheles mosquitoes older than three gonotrophic cycles.
Mosquito salivary antigens Two years Presence of mosquito salivary antigens in human blood as a measure for mosquito biting rates among cohort participants
ATSB removal rate Two years The proportion of ATSBs that have been moved/removed
Household use of LLINs in the setting of ATSBs Two years The proportion of children aged 1-\<15 years enrolled in a cohort study who used an LLIN the night prior
Cost-effectiveness Two years Incremental cost-effectiveness of ATSB above the standard of care measured through costing of intervention and efficacy outcomes
Trial Locations
- Locations (9)
Naya Health Centre
🇰🇪Siaya, Siaya County, Kenya
Rabar Dispensary
🇰🇪Siaya, Siaya County, Kenya
Benga Dispensary
🇰🇪Siaya, Siaya County, Kenya
Manyuanda Health Centre
🇰🇪Siaya, Siaya County, Kenya
Nyadhi Dispensary
🇰🇪Siaya, Siaya County, Kenya
Boro Dispensary
🇰🇪Siaya, Siaya County, Kenya
Rambugu Dispensary
🇰🇪Siaya, Siaya County, Kenya
Rageng'ni Dispensary
🇰🇪Siaya, Siaya County, Kenya
Ong'ielo Model Health Centre
🇰🇪Siaya, Siaya County, Kenya