Twelve-Hour Duration Testing of Cream Formulations of Three Repellents Against Amblyomma americanum

摘要

The repellent efficacies of the U.S. military repellent 33% N,N- diethy l-3-methylbenzamide (deet), 10% and 20% (1S, 2 'S) 2-methylpiperidinyl-3- cyclohexene- 1-carboxamide (SS220) and 10% and 20% 1-methyl-propyl-2- (hydroxyethyl)- 1-piperidinecarboxylate (Bayrepel) cream formulations on human volunteers against the lone star tick Amblyomma americanum (L.) were evaluated in a simulated forest floor environment over a 12-h testing period. At 2-h intervals, volunteers, with repellent applied in a 5-cm-wide band around each ankle, stood for 5 min in plastic tubs containing leaf litter and 100 host- seeking A. americanum nymphs. Ticks were allowed to remain on a volunteer s feet and ankles for an additional 5 min after the volunteer exited the tub. All repellent formulations provided high levels of protection for the entire 12 h. No ticks crossed 5-cm-wide bands of 20% SS220 and Bayrepel during any challenge, and thus 100% protection was afforded throughout the test. These formulations showed a long lasting efficacy hitherto unknown in tick repellents intended for use on human skin.