Failure of permethrin treated military uniforms to protect against a laboratory maintained knockdown resistant (kdr) strain of aedes aegypti

Authors: ESTEP, ALDEN - Navy Entomology Center Of Excellence, Cmave Detachment; Sanscrainte, Neil; Cuba, Ingeborg; Allen, Greg; BECNEL, JAMES - Retired ARS Employee; Linthicum, Kenneth - Ken

Submitted to: Journal of the American Mosquito Control Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2020
Publication Date: 6/1/2020
Citation: Estep, A.S., Sanscrainte, N.D., Cuba, I., Allen, G.M., Becnel, J.J., Linthicum, K. 2020. Failure of permethrin treated military uniforms to protect against a laboratory maintained knockdown resistant (kdr) strain of aedes aegypti. Journal of the American Mosquito Control Association. 36(2):127-130. https://doi.org/10.2987/19-6906.1.
DOI: https://doi.org/10.2987/19-6906.1

Interpretive Summary: Mosquito-borne diseases are a global problem and a continued threat to public and military health. Emergence of resistance to the primary class of pesticides may lead to failure of some methods used to protect people from disease. In this study, we examine whether pesticide treated uniforms, commonly used by the US and German military forces, work as effectively as expected when the mosquito is resistant to the pesticide. We make two conclusions; the uniforms fail when exposed to pesticide resistant mosquitoes, and that DEET repellent is still effective. We discuss how this may effect the risk of disease transmission.

Technical Abstract: Military forces, as well as the recreational industry, rely on the repellent properties of permethrin-treated fabrics and N, N-Diethyl-meta-toluamide (DEET)-based lotions to provide protection from disease vectors and hematophagous organisms. The combination of DEET on exposed skin and permethrin treated uniform fabric is the main countermeasure used by operational US military forces. However, concerns have been raised as resistance to the pyrethroid class of insecticides becomes more common, particularly in disease vectors like Aedes aegypti and anopheline species. A few published reports indicated strong pyrethroid resistance can cause failure in treated fabrics while a more recent report indicated continued efficacy against a resistant vector. More data are needed therefore to better understand these contrasting results. In this initial study, volunteers were exposed to 2 strains of Ae. aegypti, the susceptible ORL1952 strain and the >60-fold permethrin -resistant Puerto Rico (PR) strain while wearing permethrin-treated or untreated FRACU III army combat uniform sleeve fabric or DEET-treated forearms. The levels of toxicologic and genetic resistance in both strains were confirmed both by CDC bottle bioassay and knockdown resistance (kdr) genotyping. DEET was nearly 100% effective against both the susceptible and resistant strains. In contrast, permethrin-treated fabric was greater than 98% effective against the susceptible ORL1952 strain but provided no protection against the resistant PR strain relative to untreated control sleeves. These results confirm that pyrethroid-resistant vectors can compromise the efficacy of permethrin-treated uniforms, the major component of the DoD’s recommended personal protective repellent system. Additional testing with resistant field strains are needed to better understand the risk to service members.