Project Lead(s): Prosper Chaki
New reports suggest that malaria vectors are undergoing a behavioural shift, with disease-spreading mosquitoes increasingly feeding and resting outdoors. The composition of the dominant vector species of mosquitoes is also changing.
Implemented in Tanzania, the project aimed to exploit the biting behaviour of Anopheles gambiae s. – the major vector species in the region. Most bites from the Anopheles gambiae s. occur on the feet and legs of their human hosts, so protecting the lower limbs may significantly reduce the biting intensity.
The study aimed to demonstrate that individuals using repellent-impregnated footwear (RIF) would receive significantly fewer mosquito bites, compared to individuals not using this impregnated footwear, and are more likely to be protected from malaria transmitted by mosquito bites.
The repellant used was transfluthrin, a pyrethroid insecticide, which was mixed with synthetic resins to ensure slow release. This was impregnated in locally grown sisal with different doses.
Rubber, plastic and leather sandals were purchased and the impregnated sisal strips were sewn onto these sandals in different designs to improve community acceptance and allow people their preferred fashion.
The study was carried out in a semi-field system (SFS), situated in the natural ecosystem of the target vector and exposed to ambient conditions necessary for the completion of the life cycle of the vector.
The mosquitoes used in these experiments were laboratory-reared Anopheles arabiensis (Ifakara strain).
Male volunteers aged between 18 and 40 years participated in the study.
Hessian strips used were impregnated with different concentrations of technical-grade transfluthrin, donated by SC Johnson (SC Johnson Home Hygiene Products), and tested.
Controlled tests were carried out with volunteers wearing RIF footwear, sitting at a randomly assigned position 20m away from an individual wearing non-impregnated footwear.
Results showed that repellent-impregnated footwear provided significant protection from mosquito bites, with the intervention providing >70% efficacy against An. gambiae s. bites.
RIF provides a potential intervention to supplement current interventions outdoors and, in the early evening, a focus that is becoming increasingly important in malaria transmission as we move from sustained malaria control to elimination.
Information on the project has been presented at conferences and a paper on the study is being prepared.
After determining the efficacy of the prototype in semi-field and field settings, the project team intends to evaluate the efficacy of this intervention in the community and against malaria transmission. To achieve this goal, they will seek support from industrial partners that promote the development of essential technologies.