Permethrin: An underused tool for prevention of tick-borne infection
The authors of new research in the Journal of Medical Entomology conclude that permethrin-treated clothing is important for decreasing the risk of tick bites in military personnel.
Permethrin treated clothing is often recommended as an evidence-based means of preventing tick bites. Unfortunately, in Canada, there are limited options for purchasing permethrin treated clothing and permethrin spray is not easily available in the 0.5% concentration suitable for do-it-yourself treatment of clothing.
A recently-published study in the Journal of Medical Entomology authored by Nadolny and colleagues looks at the use of permethrin treated uniforms for American military personnel over a nine year period as part of a program called “Military Tick Identification/Infection Confirmation Kit Program (MilTICK)”.
Service personnel self-reported whether they were wearing permethrin treated uniforms at the time of tick bites. Ticks were examined for presence or absence of engorgement as a proxy for likelihood of pathogen transmission.
A total of 13,795 ticks were submitted with permethrin data. In the absence of permethrin 27% of ticks had fed to engorgement while in the presence of permethrin 12% of ticks were engorged.
During the study the proportion of engorged ticks increased over time, likely a reflection of decreased effectiveness of permethrin with age and multiple washings. Care instructions for the uniforms were not always followed. For example, some cadets reported dry-cleaning their uniforms, a process which removes most of the permethrin.
The authors conclude that permethrin-treated clothing is important for decreasing the risk of tick bites in military personnel. They further suggest that permethrin treated clothing is an underused approach for prevention in the general public.
It seems likely that this is particularly true in Canada. However, even with permethrin treated clothing, tick avoidance is necessarily multi-faceted. Don’t forget repellent (recommended with 20% picaridin (Piactive) or 25%-30% Deet) And ALWAYS do a thorough tick check!
Citation
Nadolny, R., Jones, J., Taylor, B. J., Bowman, L., & Harkins, K. (2024). Effects of permethrin-treated uniforms on tick submissions to a military passive tick surveillance program. Journal of Medical Entomology. https://doi.org/10.1093/jme/tjae111
