Mosquito Bites and Insect Repellents: What to Tell Your Patients

Audrey Lenhart, PhD, MPH


July 06, 2015

Editorial Collaboration

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Hello. My name is Dr Audrey Lenhart, of the Entomology Branch, Division of Parasitic Diseases and Malaria at the Centers for Disease Control and Prevention (CDC).

I'm pleased to speak with you as part of the CDC Expert Commentary Series on Medscape, about the important role that insect repellents play in preventing malaria and other mosquito-borne infections.

Mosquitoes transmit diseases that kill as many as 750,000 people a year.[1] Globally, there are limited vector-control options to effectively prevent and mitigate mosquito-borne disease threats. Until better vaccine and vector-control options are available, the best way to prevent most mosquito-borne diseases is to avoid mosquito bites.

For some mosquito-borne diseases, such as malaria, an antimalarial drug is generally recommended. However, in some areas, such as El Salvador and Azerbaijan, that only report rare cases of malaria, CDC recommends solely mosquito avoidance to prevent infection. If an antimalarial drug is recommended, healthcare providers should discuss with their patients the importance of taking the drug as prescribed to prevent malaria infection.

For other mosquito-borne diseases, such as West Nile, dengue, and chikungunya, no vaccines are available to prevent disease and no drugs are available for treatment. Therefore, preventing infective mosquito bites, primarily through use of insect repellents, is the best way to prevent infection.[2]

However, numerous studies have shown that a majority of travelers do not regularly use insect repellents as recommended.[3,4,5,6] Fears about the safety and smell of repellents are common barriers, as is the inappropriate timing of application or irregular use of products. Therefore, it is vital that travelers likely to be exposed to infective mosquitoes are well counseled on:

  • Which mosquito-borne diseases are common in the area they are traveling to;

  • When mosquitoes are most actively biting (daytime vs from dusk to dawn); and

  • How to select and properly apply an effective insect repellent to themselves and their children.

Products containing the following four Environmental Protection Agency (EPA)-registered active ingredients provide hours of protection against disease-carrying mosquitoes, can be applied to skin and clothing, and are more reliable options than natural product repellents[7,8]:

  • DEET;

  • IR3535;

  • Oil of lemon eucalyptus (OLE) or PMD (the abbreviated name for the synthesized version of OLE) and;

  • Picaridin (KBR 3023).

Some examples of repellent brand names can be found on a new insect repellent fact sheet for consumers.

Before applying a repellent, encourage your patients to read the label first.

The label provides the active ingredients, directions for use, duration of repellency, and whether the product is EPA-registered.

Remind patients about basic safety issues when applying a repellent:

  • Follow the label directions to ensure proper use.

  • Apply repellents only to exposed skin and/or clothing.

  • Do not use under clothing.

  • Do not apply near eyes and mouth, and apply sparingly around ears.

  • When using sprays, do not spray directly into face; spray on hands first and then apply to face.

  • Never use repellents over cuts, wounds, or irritated skin.

  • Do not spray in enclosed areas.

  • Avoid breathing a spray product.

  • Do not use near food.

  • After returning indoors, wash treated skin and clothes with soap and water.

  • Store insect repellents safely out of the reach of children, in a locked utility cabinet or garden shed.

EPA does not recommend any additional precautions for repellent use by pregnant or nursing women.

Education for parents should emphasize:

  • Before an insect repellent is applied to a child, the label should be carefully read for directions.

  • Insect repellents should not be sprayed directly on a child.

  • An adult should put a small amount of insect repellent in their hands and then apply on the child's skin not covered by clothing.

  • Insect repellent should never be applied on the child's hands.

  • After returning indoors, the child's treated skin and clothes should be washed with soap and water or the child can bathe.

  • Insect repellents should not be applied to children younger than 2 months of age. They should instead be protected from mosquitos by draping their infant carrier with fitted mosquito netting.

  • The American Academy of Pediatrics recommends lower concentrations of DEET (no more than 30%) on children.

  • Products containing lemon eucalyptus should not be used on children under the age of 3 years.

  • If a suspected reaction to an insect repellent occurs, such as a rash, the parents should stop using the insect repellent and wash the area with soap and water.

  • If medical evaluation of the reaction is sought, instruct the person to bring the insect repellent container to the office visit.

The Poison Control hotline can be consulted as well at 1-800-222-1222.

Additional measures to prevent mosquito bites include wearing a long-sleeved shirt, long pants, and a hat when outdoors, and sleeping in a well-screened or air-conditioned room, or under an insecticide-treated bed net, especially in areas where malaria transmission occurs, because these mosquitoes bite mostly at night (dusk until dawn).

Travelers should also be advised to bring their own repellent because some products available internationally may contain ingredients not registered in the United States.

Web Resources

CDC: Malaria

CDC: Travelers' Health

CDC: Malaria Fact Sheets, Brochures, and Posters

CDC: Malaria and Travelers

Audrey Lenhart, PhD, MPH, is a research entomologist in the Entomology Branch of the Division of Parasitic Diseases and Malaria in the Center for Global Health at the Centers for Disease Control and Prevention in Atlanta, Georgia, where she provides technical support to the Amazon Malaria Initiative and runs a research laboratory that focuses on the biology and control of mosquitoes that transmit malaria and other parasitic diseases, as well as dengue fever. She is Honorary Research Fellow at the Liverpool School of Tropical Medicine and is adjunct faculty in the Department of Environmental Sciences at Emory University. Dr Lenhart received her PhD from the Liverpool School of Tropical Medicine and her MPH from the Rollins School of Public Health at Emory University.