Using repellents to avoid mosquito-borne diseases

By Mark Gallo
This item appears on page 54 of the September 2017 issue.
In some places — like this bamboo grove in the Arashiyama district west of Kyoto, Japan — travelers need to be aware that mosquitoes may be present. Photo by Mark Gallo

Understandably, the Zika virus is getting plenty of attention right now for travelers considering visiting Brazil or the Caribbean; however, mosquito-borne diseases like dengue fever, malaria and chikungunya are much more widespread.

Dengue is considered a leading cause of illness and death in the tropics, according to the Centers for Disease Control & Prevention (CDC), with an estimated 400 million people infected yearly. It occurs in more urban areas than does malaria and is transmitted by the Aedes aegypti mosquito, the same species responsible for the Zika virus.

Malaria occurs in warm, humid regions. There were an estimated 200 million cases in 2015. The disease comes from the Plasmodium parasite that infects Anopheles mosquitoes. It is most prevalent in sub-Saharan Africa, southern India and New Guinea.

Chikungunya is a virus transmitted by the Aedes mosquito and occurs in the Caribbean, Mexico, South America, equatorial Africa, parts of the Middle East, India and Southeast Asia. 

Most of us are aware that deer ticks can be infected with lyme disease, but you should also be aware that this disease — called borreliosis outside of the US — occurs in Central and Eastern Europe as well as southern Canada.

Visit to learn more about what diseases may be prevalent in your destination country and which vaccines and preventative measures the CDC recommends.

The best bug repellents 

No one likes the idea of rubbing chemicals on their skin to ward off bugs, but the risk of getting seriously ill from a mosquito bite in the tropics is very motivating. 

Follow the CDC’s recommendations and use only EPA-registered bug repellents. 

Testing by Consumer Reports determined that repellents with 20% picaridin or 25% DEET were the most long-lasting and effective against mosquitoes. Consumer Reports specifically recommended avoiding products with citronella, lemongrass oil or rosemary oil, as they were ineffective. 

In the Arashiyama district of Japan's Honshu Island, conditions favorable to growing rice may also bring an increase in mosquitoes. Photo by Mark Gallo

Lastly, remember, when applying both sunscreen and bug repellent, apply the sunscreen first.

• One product recommended by Consumer Reports is a 20% solution of picaridin insect repellent. You can find it in a carryon-sized, 3-ounce spray-pump bottle.

• Another product — insect repellent wipes with 20% picaridin — can be used to apply the repellent exactly where you want it.

• Insect-repellent lotion with 30% DEET is recommended by Dr. Mary-Louise Scully, Director of the Sansum Clinic – Travel & Tropical Medicine Center of Santa Barbara. You can find it in a 2-ounce, carryon-sized tube.

• A 30% DEET spray is available in a 3.4-ounce bottle, the maximum carry-on size allowed. Wipes with 30% DEET are also available from several suppliers.

• Permethrin insecticide spray is available for clothing. A 6-ounce can contains enough to cover one entire outfit, and it lasts for up to six washings. 

This is a synthetic version of a chemical produced naturally in chrysanthemums, and it is CDC-recommended. In fact, several clothing brands offer field shirts, pants, hats and socks pretreated with permethrin. 

Adding credence to permethrin’s effectiveness, the US military has been using treated uniforms since the 1990s. 

Note that you should still apply insect repellent to exposed skin even when wearing permethrin-treated clothing.

Mark Gallo is the owner of Circa­Terra Travel Outfitters (Santa Barbara, CA; 805/568-5402, circaterra, and he can be reached at