Long-lasting permethrin-impregnated clothing: protective efficacy against malaria in hyperendemic foci, and laundering, wearing, and weathering effects on residual bioactivity after worst-case use in the rain forests of French Guiana.

Personal protective measures against hematophagous vectors constitute the first line of defense against arthropod-borne diseases. However, guidelines for the standardized testing and licensing of insecticide-treated clothing are still lacking. The aim of this study was to analyze the preventive effect of long-lasting polymer-coated permethrin-impregnated clothing (PTBDU) against malaria after exposure to high-level disease transmission sites as well as the corresponding loss of permethrin and bioactivity during worst-case field use. Between August 2011 and June 2012, 25 personnel wearing PTBDUs and exposed for 9.5 person-months in hyperendemic malaria foci in the rain forest of French Guiana contracted no cases of malaria, whereas 125 persons wearing untreated uniforms only, exposed for 30.5 person-months, contracted 11 cases of malaria, indicating that PTBDU use significantly (p = 0.0139) protected against malaria infection. In the field, PTBDUs were laundered between 1 and 218 times (mean 25.2 ± 44.8). After field use, the mean remaining permethrin concentration in PTBDU fabric was 732.1 ± 321.1 min varying between 130 and 1270 mg/m2 (mean 743.9 ± 304.2 mg/m2) in blouses, and between 95 and 1290 mg/m2 (mean 720.2 ± 336.9 mg/m2) in trousers. Corresponding bioactivity, measured according to internal licensing conditions as KD99 times against Aedes aegypti mosquitoes, varied between 27.5 and 142.5 min (mean 47.7 ± 22.1 min) for blouses, and between 25.0 and 360 min (mean 60.2 ± 66.1 min) for trousers. We strongly recommend the use of long-lasting permethrin-impregnated clothing for the prevention of mosquito-borne diseases, including chikungunya, dengue, and zika fevers, which are currently resurging globally.

Factory-based permethrin impregnation of uniforms: residual activity against Aedes aegypti and Ixodes ricinus in battle dress uniforms worn under field conditions, and cross-contamination during the laundering and storage process.

The factory-based permethrin coating technique has only recently been developed. Consequently, no data are available on residual activity, laundering, and weathering resistance in impregnated battle dress uniforms (BDUs) worn under military deployment conditions, or on the cross-contamination potential of such uniforms. Herein, factory-impregnated BDUs worn-out during military deployment to Afghanistan were investigated for residual permethrin concentration, residual efficacy against arthropod vectors, and cross-contamination during laundering and storage. When compared with BDUs subjected to 50 defined washings using the U.S. Insect/Arthropod Repellent Fabric Treatment method, no significant differences in efficacy were observed against Aedes mosquitoes, but remaining knockdown activity in Ixodes ticks was significantly better in polymer-coated BDUs. BDUs impregnated by the polymer-coating method were found to be effective for the life of the uniform, ensuring protection of soldiers in the field from arthropod vectors, while causing less cross-contamination than those treated by the Insect/Arthropod Repellent Fabric Treatment method.

Contact toxicity and residual activity of different permethrin-based fabric impregnation methods for Aedes aegypti (Diptera: Culicidae), Ixodes ricinus (Acari: Ixodidae), and Lepisma saccharina (Thysanura: Lepismatidae).

The effectiveness and residual activities of permethrin-impregnated military battle dress uniforms were evaluated by comparing a new company-manufactured ready-to-use polymer-coating method with two "dipping methods" that are currently used to treat uniforms. Residual permethrin amounts and remaining contact toxicities on treated fabrics before and after up to 100 launderings were tested against Aedes aegypti (L.), Ixodes ricinus (L.), and Lepisma saccharina (L.). The residual amount of permethrin was considerably higher with the polymer-coating method: 280 mg a.i./m2 after 100 launderings, compared with 16 and 11 mg a.i./m2, respectively, obtained when using the two dipping methods. Hard ticks were most susceptible to the new polymer-coating method, resulting in prelaundering 100% knockdown times of 7.0 +/- 0.9 min, whereas equivalent times for the dipping methods were 7.9 +/- 0.35 min and 8.0 +/- 0.54 min, respectively. After 100 launderings, 100% knockdown of I. ricinus nymphs was reached at 15.2 +/- 1.04 min using the polymer-coating method, compared with 178.8 +/- 24.7 min and 231 +/- 53.6 min, respectively, using the dipping methods. Similar results were obtained for Ae. aegypti and L. saccharina, indicating that the polymer-coating method is more effective and efficient when compared with the dipping methods.