Project Lead(s): Johnson Odera
Diseases transmitted by insect vectors remain major causes of morbidity and mortality.
Treated clothing can offer personal protection and reduce vector transmission when used either indoors or outdoors.
To date, only permethrin is used and registered for the treatment of protective clothing against blood-sucking insects, and the use of permethrin-treated clothing is limited to the tourism and military sectors.
The objective of the project was to develop affordable, protective clothing against blood-sucking parasites.
The team set out to identify active ingredients (AI) that could replace permethrin for treatment of protective clothing. Furthermore, they aimed to develop innovative knitting patterns that would make permethrin-treated clothing safer and more cost-effective than the commercially available alternative.
Candidate AIs of four essential oils or essential oil derivatives and one pyrethroid derivative were tested. Additionally, a unique fabric knitting pattern treated with permethrin was developed and tested.
Three different formulation technologies were used to treat fabric and evaluated by direct comparison with a commercially available permethrin-coated fabric (Insect Shield®).
Suitability of a treated fabric to confer long-term AI release and offer protection was assessed by measuring wash resistance and blood-feeding inhibition (BFI) of mosquitoes when exposed to a blood meal source in conjunction with the treated fabric being tested.
One essential oil derivative (based on incorporation) and one essential oil (based on microencapsulation) formulation were selected as the best candidates to replace permethrin in the long term. These will, however, require further evaluation. A unique textile knitting pattern that allows online incorporation of a very low dose of permethrin into the yarn used for making clothing fabric has been developed.
The innovative fabric knitting pattern developed in the course of this project limits the presence of the permethrin only to the outer surface of the fabric, with no direct contact between the treated material and human skin. In addition, the new pattern requires 35–55% less AI (permethrin), thus making it both safer and more cost-effective. This technology has the potential for immediate scaling after refinement of dose release rates and risk assessment.
Bioassays conducted using the formulations developed in this study maintained almost full efficacy (>90% BFI) after 80 washes. Under similar conditions, the commercially available reference material started to lose efficacy after 70 washes (<50% BFI).
The two non-permethrin active ingredients and the permethrin-based formulation, when combined with an innovative knitting pattern, will provide protective garments that are highly effective, wash-resistant, safer and more economical than currently available commercial technology.
Detailed results have not been disseminated due to the commercial sensitivity and confidential nature of the work, but will be disseminated once the final choice of AIs and technologies, have been confirmed and scaling up of the project begins.