Advice for protection against mosquitoes and ticks.

Emerging vector-borne diseases have become a concern for travelers and nontravelers alike. Although Ebola has dominated recent headlines, tropical arboviruses such as dengue and chikungunya have more quietly reached the United States. Local transmission of chikungunya virus was first documented in the United States in July 2014, and local spread of dengue has occurred in Florida, Texas, and Hawaii.1,2 West Nile virus was initially detected in the United States in 1999 and has since been found in every state in the continental United States.3 Furthermore, tickborne diseases such as Lyme disease, southern tick-associated rash illness, and Rocky Mountain spotted fever are endemic to many parts of the country. The changing epidemiology of vector-borne diseases highlights the importance of personal protective measures, including the use of insect repellents. There are many myths and misperceptions about repellents, and there is increasing consumer interest in “natural” alternatives to conventional products. Therefore, family physicians should be knowledgeable about which products are effective and safe. Table 1 lists effective insect repellents registered by the Environmental Protection Agency (EPA).4 N,N-diethyl-m-toluamide (DEET) is the first-line mosquito repellent, and numerous studies have demonstrated its effectiveness and safety.4,5 Repellents with 20% to 50% DEET provide up to several hours of protection (there is no significant increase in effectiveness with concentrations greater than 50%.) DEET-impregnated wristbands repel mosquitoes only from areas covered by the band, so their usefulness is limited. DEET is considered safe in the second and third trimesters of pregnancy and in children older than two months.4,5 It should be noted that it can damage plastics and synthetic materials; therefore, care should be taken when it is used around plastic watches, eyeglasses, and synthetic fabrics. Effective alternatives to DEET include Picaridin (KBR 3023) and IR3535 (3-[N-butyl-N-acetyl]-aminopropionic acid, ethyl ester).4 Picaridin does not affect plastic or synthetic materials and is essentially odorless. IR3535 is available in the United States as Avon Skin-So-Soft Bug Guard Plus IR3535 lotion. Picaridin and IR3535 are generally considered safe in children and pregnant women. There is growing interest in natural insect repellents, but most are not recommended because of lack of effectiveness.6 An exception is oil of lemon eucalyptus (p-menthane-3, 8-diol), a plant-based repellent that has been shown to have effectiveness and duration of action comparable to DEET. It is the only plant-based repellent recommended by the Centers for Disease Control and Prevention,4 but should not be used by pregnant women or children younger than three years. Studies have also shown that a repellent combining 2% soybean oil with other oils and emollients protects against mosquitoes for 1.5 to 7.2 hours.5 This type of repellent is available in the United States as Bite Blocker but is not registered by the EPA as a repellent. Citronella is a common ingredient in many natural repellents. However, citronellabased products at lower concentrations have Editorials