Effectiveness of repellent formulations containing deet against mosquitoes in northeastern Thailand

Formulations of the repellent diethyl methyl benzamide (deet) were evaluated against mosquitoes in field tests conducted in Sisaket Province, northeastern Thailand. Thirty-three percent deet in an applicator stick provided > or = 87.1% protection against primarily Culex vishnui, Cx. gelidus, and Cx. tritaeniorhynchus for up to 5 h, and 50% deet in ethanol provided > or = 93.3% protection against Anopheles sp. and culicines for up to 8 h. The U.S. Army Extended Duration Repellent Formulation ([EDRF], containing 33% deet), 50% deet in ethanol, and 75% deet in ethanol provided complete protection for up to 6 h against primarily Culex vishnui and Anopheles dirus.