Passive prophylaxis with permethrin-treated tents reduces mosquito bites among North American summer campers.
OBJECTIVE
Over 2 million adolescents participate in summer-camp experiences, placing themselves at risk for mosquito-borne illness. Insect repellent is recommended but often not used. It is unknown whether permethrin treatment of a location, such as a campsite, provides passive prophylaxis reducing mosquito bites among all persons in the immediate vicinity.


METHODS
This randomized, double-blind controlled trial used 0.4% permethrin (2.5% permethrin diluted by 7 parts water) sprayed once onto the external surface of canvas tents at a Boy Scout summer camp. During a 9-week period, subjects (n = 545) completed nightly mosquito-bite and -landing counts for 5 minutes at dusk and recorded insect-repellent use within 2 hours of counting. Weekly mosquito sampling with CO2-baited Centers for Disease Control and Prevention traps occurred at study campsites. The primary outcome measure was the number of mosquito bites per 5 minutes.


RESULTS
A total of 1614 person nights averaged 5.1 +/- 7.2 (+/- SD) mosquito bites per 5 minutes. The permethrin-treated campsites had decreased mosquito landings and bites (relative risk reduction [RRR] 44%; 95% CI 34% to 55%; P < .001) compared with controls. Insect repellent was used only 32% of nights, decreasing bites by 36% (RRR 36%; 95% CI 25% to 47%; P < .001). Permethrin was superior to insect repellent alone (RRR 20%; 95% CI 4% to 37%; P = .01).


CONCLUSIONS
Permethrin treatment of tents is an effective, inexpensive public health measure to reduce mosquito bites. Permethrin is effective among all individuals in a camping setting and was more effective than topical insect repellent alone, which, although recommended, was inconsistently used.
Boulware
David R
DR
Division of Infectious Disease and International Medicine, University of Minnesota, MMC 250, 420 Delaware St SE, Minneapolis, MN 55455, USA. Boulw001@umn.edu
Beisang
Arthur A
AA
D000293:Adolescent; D000330:Aedes; D000818:Animals; D002165:Camping; D002648:Child; D004311:Double-Blind Method; D006801:Humans; D007299:Insect Bites and Stings / Q000517:prevention & control*; D007303:Insect Vectors; D007306:Insecticides / Q000008:administration & dosage*; D008297:Male; D009032:Mosquito Control / Q000379:methods; D026023:Permethrin / Q000008:administration & dosage*; D016896:Treatment Outcome; D014901:West Nile Fever / Q000517:prevention & control; D014922:Wisconsin
D007306:Insecticides; D026023:Permethrin