ABSTRACT
Background The worldwide threat of arthropodtransmitted
diseases, with their associated morbidity
and mortality, underscores the need for effective insect
repellents. Multiple chemical, botanical, and “alternative”
repellent products are marketed to consumers.
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 volunteers
to test the relative efficacy of seven botanical
insect repellents; four products containing N,N-diethylm-toluamide,
now called N,N-diethyl-3-methylbenzamide
(DEET); a repellent containing IR3535 (ethyl
butylacetylaminopropionate); three repellent-impregnated
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 concentrations
of DEET provided longer-lasting protection. A
formulation containing 23.8 percent DEET had a mean
complete-protection time of 301.5 minutes. A soybeanoil–based
repellent protected against mosquito bites
for an average of 94.6 minutes. The IR3535-based repellent
protected for an average of 22.9 minutes. All
other botanical repellents we tested provided protection
for a mean duration of less than 20 minutes. Repellent-impregnated
wristbands offered no protection.
Conclusions Currently available non-DEET repellents
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.)