Impact of Wearing and Washing/Drying of Permethrin-Treated Clothing on Their Contact Irritancy and Toxicity for NymphalIxodes scapularis(Acari: Ixodidae) Ticks

Abstract

Permethrin-treated clothing is available as consumer products to prevent bites by tick and insect pests. We used bioassays to examine the impact of wearing and washing/drying of permethrin-treated shirts, pants, and socks, and wearing of treated shoes, on their contact irritancy and toxicity for nymphal Ixodes scapularis Say (Acari: Ixodidae) ticks, the primary vectors in the eastern United States of the causative agents of Lyme disease, human anaplasmosis, and human babesiosis. Pristine permethrin-treated clothing displayed strong contact irritancy and toxicity toward I. scapularis nymphs, with 0–30% of ticks across clothing types and tick sources displaying normal movement 1 h after forced contact for 30–120 s with treated textile. Following 16 d of wear and 16 rounds of machine washing and drying, we recorded reduced concentrations (by 50–90%) of permethrin, compared with pristine treated clothing, from shirts, pants, and socks. This loss of permethrin was associated with reduced contact irritancy and toxicity for ticks after forced contact with worn and washed/dried treated clothing: 31–67% of ticks displayed normal movement 1 h after contact. Nevertheless, the worn and washed/dried treated clothing was still superior to nontreated textile, for which 90–100% of ticks displayed normal movement. Treated shoes, which were worn but not washed, remained as toxic to the ticks as pristine treated shoes. We caution that these laboratory bioassay results should not be interpreted as being directly indicative of the outcome of using washed/worn permethrin-treated clothing in daily life. Although wear and washing/drying did reduce the irritancy and toxicity of permethrin-treated clothing for I. scapularis nymphs more than we had expected, the remaining effect might still reduce the risk of tick bites in a real-life scenario.

Three molecules found in rosemary or nutmeg essential oils repel ticks (Dermacentor variabilis) more effectively than DEET in a no‐human assay

“…The lack of known host cues mean that the results must be contextualized with further studies that are closer to the field. Also, the reason for the tick to cross onto the repellent‐treated surface is unclear, and for future bioassays, changing the dish from horizontal to a 45° angle could encourage host‐seeking behavior from the ticks 26 . The concentration of active ingredients was chosen to have DEET give middle to low repellent times, which was done to allow for statistical resolution of multiple compounds with repellent times greater than DEET.…”

“…Also, the reason for the tick to cross onto the repellent-treated surface is unclear, and for future bioassays, changing the dish from horizontal to a 45°angle could encourage host-seeking behavior from the ticks. 26 The concentration of active ingredients was chosen to have DEET give middle to low repellent times, which was done to allow for statistical resolution of multiple compounds with repellent times greater than DEET. This, however, meant that our DEET treatment was at a lower concentration than found in some commercial products.…”

Powassan Virus Encephalitis Following Brief Attachment of Connecticut Deer Ticks

“…Parents should be educated about the need to treat outdoor clothing with permethrin, an effective mode of preventing tick bites. Permethrin binds tightly to fabric, lasting for at least a dozen wash cycles [31]. Although there is some repellent action from permethrin, contact with treated fabric will kill all ticks within 2 hours and thus reduce the risk that ticks brought into the home will seek hosts there.…”

Human and Veterinary Vaccines for Lyme Disease

“…In both human and veterinary medicine, acaricides are available for use. The application of permethrin (0.5%) (Connally et al, 2018) to clothing is one preventative strategy recommended by the CDC. Permethrin is long-lasting and has been demonstrated to convey significant protection against bites from I. scapularis in laboratory studies and sustained protection against bites by Amblyomma americanum ticks in field tests.…”