Preventing Zika and Other Mosquito-borne Diseases While Traveling Outside of the U.S.
Every year, millions of US residents travel to countries where mosquito borne diseases including Zika, dengue, chikungunya, yellow fever , Japanese encephalitis and malaria are common. These diseases can cause severe illness and death in some cases. As the general public has become aware of the threat of Zika due to the recent outbreak in the Western Hemisphere, it is important to learn what measures a traveler can take to prevent not only Zika, but other mosquito borne diseases that may be associated with an even higher morbidity and mortality.
When and why do mosquitoes bite and which diseases can they transmit?
Only the female mosquito bites for blood, which she needs to mature her eggs. To find a host, female mosquitoes are attracted to chemical compounds emitted by mammals including humans. These compounds include ammonia, carbon dioxide, lactic acid and octanol.
Mosquito bites can transmit viruses or parasites responsible for a variety of infections. Below is a table with certain mosquitos, some of the diseases they spread, and the biting times.
Daytime (Dawn to Dusk)
Nighttime (Dusk to Dawn)
West Nile Virus
Nighttime (Dusk to Dawn)
Why is mosquito bite prevention needed to prevent diseases?
There is no preventive medicine or vaccine for certain mosquito borne infections including Zika, dengue and chikungunya. Although antimalarial drugs are very effective in preventing malaria, they are not 100% effective. Therefore, taking measures to decrease the chances of being bitten will decrease the probability of getting any mosquito borne illness.
What are the most effective ways to avoid being bitten by mosquitoes?
- Apply mosquito repellent
- Wear protective clothing
- Use bed nets if not sleeping in air conditioned, well screened area.
Let us understand each of the above precautions in more detail.
Use insect repellants on exposed skin. While the purpose of this article is to discuss preventing mosquito borne illnesses, the repellents also prevent diseases spread by other biting insects. When using sun screen, apply the sun screen first, then apply the insect repellent. Combined sunscreen and repellent products are not recommended. To prevent mosquito borne-illnesses it is important to use the repellants during the biting times of the mosquitoes that carry the diseases. This will vary depending on location Let us learn about the two most effective mosquito repellents available today.
DEET: N, N -Diethylmetatoluamide
- Very effective and long safety record (used on millions of children for over 5 decades)
- Apply to exposed skin
- Use products with 25-50% DEET (5-7% only lasts1-2 hours and products over 50% do not provide much more increased duration of protection)
Brand names: OFF, Cutter, Sawyer, Ultrathon
- Picardin offers protection that's comparable to DEET when used at concentrations of 20% or higher
- Picardin is nearly odorless- a good alternative if you are sensitive to the smells of insect repellent.
Brand Names: Cutter advanced, Natrapel, Sawyer
There are other Environmental Proctection Agency (EPA) approved insect repellants, including Oil of Eucalyptus and IR3535, but they have not been as extensively studied.
Are insect repellents safe?
- Both DEET and Picaridin are safe for children >2 months of age and in pregnancy.
- Children <2 months: use tight fitting net on infant carrier or crib.
- Children should not handle repellents. Instead, adults should apply repellents to their own hands first and then gently spread on the child’s exposed skin. Avoid applying directly to children’s hands. After returning indoors, wash your child’s treated skin and clothing with soap and water or give the child a bath. Never use repellents over cuts, wounds, or irritated skin.
- When using sprays, do not spray directly on face—spray on hands first and then apply to face.
- Do not apply repellents to eyes or mouth, and apply sparingly around ears.
- Apply on exposed skin. Do not apply to skin under clothing.
Your clothes provide a barrier between your skin and mosquitoes. By using long sleeves, long pants, closed shoes and socks during the biting times you will decrease the chances of being bitten. Tucking shirt into pants, and pants into socks can provide additional protection.
When travelling to areas of increased risk of mosquito and other insect borne diseases consider treating outer clothing and certain gear with permethrin. (Permethrin is an insecticide that kills mosquitoes and other insects)
- They can stay effective after multiple washes. Read product information to find out how long the protection will last.
- Use permethrin to treat clothing and gear (mosquito nets and tents) or purchase clothing that is pre-treated.
- Always follow the product instructions to apply the treatment.
- DO NOT use on skin.
Sleep under a bed net if you are outside or in a room that is not well air-conditioned and/or the windows are not adequately screened. Research your accommodations prior to travelling. Having a bed net that is pre-treated with permethrin can increase its effectiveness.
Select a WHOPES-approved bed net (like Pramax): compact, white, rectangular, with 156 holes per square inch, and long enough to tuck under the mattress. (WHOPES - WHO - Pesticide Evaluation Scheme)
- Use Permethrin-treated bed nets if that option is available, as these provide more protection than untreated nets.
Refer to label instructions with regards to washing permethrin-treated bed nets as well as exposing them to sunlight as this may breakdown the insecticide more rapidly
Pregnant women and travel
Pregnant women and women trying to become pregnant should consider postponing travel to Zika-affected areas, as well as areas that are at increased risk for malaria or yellow fever. If they do travel, they should speak to a travel health specialist
What is the best way to prevent getting ill while traveling?
The best way to prevent getting ill while travelling is to see a travel health specialist ideally 4-6 weeks prior to travel.
Your travel health specialist will provide:
- Recommended and required vaccines
- Prescriptions to prevent or self-treat common travel-related illnesses
- Health and safety counseling tailored to your specific itinerary, activities, and medical history