ABSTRACTBackground The worldwide th

ABSTRACT
Background The worldwide threat of arthropod- transmitted diseases, with their associated morbidity and mortality, underscores the need for effective in- sect repellents. Multiple chemical, botanical, and “al- ternative” repellent products are marketed to consum- ers. We sought to determine which products available in the United States provide reliable and prolonged complete protection from mosquito bites.
Methods We conducted studies involving 15 volun- teers to test the relative efficacy of seven botanical insect repellents; four products containing N,N-diethyl- m-toluamide, now called N,N-diethyl-3-methylben- zamide (DEET); a repellent containing IR3535 (ethyl butylacetylaminopropionate); three repellent-impreg- nated wristbands; and a moisturizer that is commonly claimed to have repellent effects. These products were tested in a controlled laboratory environment in which the species of the mosquitoes, their age, their degree of hunger, the humidity, the temperature, and the light–dark cycle were all kept constant.
Results DEET-based products provided complete protection for the longest duration. Higher concentra- tions of DEET provided longer-lasting protection. A formulation containing 23.8 percent DEET had a mean complete-protection time of 301.5 minutes. A soybean- oil–based repellent protected against mosquito bites for an average of 94.6 minutes. The IR3535-based re- pellent protected for an average of 22.9 minutes. All other botanical repellents we tested provided protec- tion for a mean duration of less than 20 minutes. Re- pellent-impregnated wristbands offered no protection.
Conclusions Currently available non-DEET repel- lents do not provide protection for durations similar to those of DEET-based repellents and cannot be relied on to provide prolonged protection in environments where mosquito-borne diseases are a substantial threat. (N Engl J Med 2002;347:13-8.)
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