Location: Mosquito and Fly Research
Project Number: 6036-32000-052-095-I
Project Type: Interagency Reimbursable Agreement
Start Date: Oct 1, 2020
End Date: Sep 30, 2021
Objective:
Discover, develop and evaluate new fabric treatments and optimize existing treatments to provide improved protection from insect bites through military clothing.
Approach:
Evaluation of bite protection of insecticide-treated fabrics provides information on how well clothing of a selected construction combined with an insecticide prevents mosquito bites compared to the bites received when the fabric is not treated. This bite protection” protocol was developed originally for permethrin-treated US Marine Corps uniforms and is now used to evaluate efficacy for treated combat uniforms supplied by the US Army and US Navy. The US Army is using results from this same protocol to guide their development of new uniforms treated with permethrin binder at the factory level. The protocol requires that at least 2 specimens of each fabric be tested on a minimum of 3 individuals at each laundering level, against two species, Ae. aegypti and An. albimanus, except for the control, which is tested once per species, per subject, per day of testing (n=18 measurements with two more for controls). Specimens are sewn into sleeves and analyzed for bite protection and permethrin content typically at the 0x- (unwashed), 20x-wash, and 50x-wash levels. Volunteers insert sleeved arms into a cage of 200 ± 25 female mosquitoes for 15 min. The order of testing is arranged from lowest to highest expected permethrin content (i.e., control then 50x-, 20x-, and 0x-washed permethrin-treated samples) to maximize mosquito feeding behavior by avoiding overstimulation observed when mosquitoes are exposed to high permethrin doses found in low number of washes. Blood-containing (“blooded”) mosquitoes are counted and a percentage blooded from the whole cage population is calculated. Abbott’s formula (Abbott 1925) is used to correct for the bite through of the untreated control sleeve. In essence, this protocol reports the level of protection afforded by the permethrin treatment on the uniform, relative to the level afforded in the same time interval for the control. Results will be reported as percent bite protection with standard errors and will be used to determine the best fabric/composition/repellent combination to produce optimum bite protection. Since the current repellent for clothing, permethrin, is the only compound registered for clothing and even then, limited to outer garments, an alternative or additional treatment, including ones with spatial effect will be sought. Alternative treatments (such as volatile pyrethroids) will be applied to or incorporated into devices placed strategically on military uniforms. Small scale “factory treatment” feasibility studies of these treated fabrics will follow. This will be accomplished with collaboration from commercial partners to produce the treated uniforms and Natick Soldier Center to perform the standardized wash cycles and to use their expertise to bind the repellent treatment onto or in the fibers. The next phase of studies will involve laboratory validation (bite protection assessment) of the “factory-treated” fabric supplied by Natick at the unwashed, 20x, and 50x-washed levels. Since these studies involve human volunteers, all participants are required to provide informed consent to participate. All data are collected in accordance with the approved Western Institutional Review Board.
