This blog will focus on another vital topic in travel medicine – Mosquito avoidance. A multitude of travel-related diseases is carried by that pesky mosquito vector. The list includes several of the most common reasons for medical prophylaxis on international trips – such as malaria, yellow fever, and Japanese Encephalitis. There is also a multitude of mosquito driven diseases in which there are no vaccinations/medications to help limit risk, some of which include dengue virus, chikungunya virus, and Zika virus – All we can do is avoid bites for prevention!
The first step is identifying the endemic risks at a traveler’s destination. If there are mosquito-transmitted disease threats we then need to focus on mosquito avoidance and/or disease prophylaxis. There are many tools at a traveler’s disposal when it comes to mosquito avoidance. Let’s start going over strategies to limit mosquito risk.
Avoiding mosquito bites is the foundation of prevention (even if medication/vaccination prophylaxis is used). The most logical initial strategy is to decrease the amount of exposed skin by wearing long sleeve shirts/pants. This, in theory, seems simple but at tropical/searing destinations this can be easier said than done. No one wants to wear turtlenecks at the beach!
Staying in air-conditioned or a screened/enclosed area can help limit mosquito exposure (and should absolutely be sought after especially while sleeping). It is recommended but again difficult to accomplish on a multitude of trips. Most people want to go out and explore the terrain of their locality. One could also plan their days around mosquito schedules – avoiding outdoor exposure between dusk and dawn (nighttime hours), the typical feeding time of Anopheles mosquitoes if there is a malaria risk; or avoiding outdoor exposure between dawn to dusk (daytime hours), this is the typical feeding time of Aedes mosquitoes if there is Yellow Fever, Dengue Fever, or Chikungunya Fever risk. Again these methods can be helpful but very cumbersome on an international trip. People tend to go out at all times of the day/night.
There are several recommended mosquito avoidance measures by the US Centers for Disease Control to help limit mosquito risk during travel. Let’s list them out:
Insecticide treated bed nets at bedtime while sleeping (Permethrin laced)
a. Clothing and bed netting treated with permethrin can repel mosquitoes for more than one week even with heavy use and washing
b. Standard permethrin nets are effective for three washes. Newer permethrin formulations can remain functional over 20 washes
c. Long-lasting insecticide impregnated nets (LLINs) can remain effective as long as three years
d. Travelers to endemic areas lacking screens or air conditioning (such as hikers/adventure seekers) should sleep under insecticide treated nets
Utilizing insect repellent (for clothing or exposed skin) –
Insect repellents recommended by the United States Centers for Malaria Disease Control and Prevention (CDC) include:
A. N-diethyl-m-toluamide (DEET):
i. Developed by U.S. Army in 1946 and has been regularly used as an insect repellant since 1957.
ii. DEET is the most widely used repellent in the world
iii. Can work for mosquitoes and ticks
iv. As a precaution, manufacturers advise that DEET products should not be used under clothing or on damaged skin, and that preparations be washed off after they are no longer needed or between applications
v. Lower percentage preparations provide a shorter duration of protection generally
1. DEET ranges in strength from 10% (for about 2 hours of protection) up to 98% (up to 10 hours). (see product label)
2. Controlled-release “micro-encapsulated” formulas of 30%-34% DEET can potentially protect for 11-12 hours (see product label)
vi. When used as directed, products containing between 10% and 30% DEET have been found by the American Academy of Pediatrics to be safe to use on children, as well as adults, but recommends that DEET not be used on infants less than two months old
i. Started as DEET alternative in Europe beginning in 1998
ii. Has been approved for use in the U.S. since 2005
iii. This agent (20 percent concentration) and DEET (35 percent concentration) have comparable efficacy
iv. Typically holds protection against malaria vectors up to eight hours after application (see product label)
v. Does note work to repel ticks as well as some competitiors
vi. Has not been shown to damage fabrics, surfaces or materials
vii. The American Academy of Pediatrics has made no recommendation on the use of picaridin for children
i. Developed by Merck in Germany in early 1980s as a DEET alternative
ii. Registered for use by the EPA in the U.S. in 1999
iii. Has activity against mosquitoes and ticks
iv. Can hold protection ranging from 2 to up to 8 hrs (see product label)
v. The EPA has approved for use citing over 20 years of European data without any substantial adverse events whether it is ingested, inhaled, or used on skin
vi. The American Academy of Pediatrics has made no recommendation on the use of IR3535 for children
D. Oil of Lemon Eucalyptus
i. chemically synthesized version of oil of lemon eucalyptus has been registered by EPA in 2000 for use as an insect repellant (see label to ensure product is EPA approved)
ii. Has activity against mosquitoes and ticks
iii. “Pure” oil of lemon eucalyptus is not registered with EPA as an insect repellent
iv. it’s potentially effective up to 6 hours (at a concentration of 30%)
v. Can cause skin irritation – not recommended for children under the age of 3 yo
vi. The American Academy of Pediatrics has made no recommendation on the use of Oil of Lemon Eucalyptus for children
E. 2-undecanone (methyl-nonyl-ketone, IBI-246)
i. Oily organic liquid manufactured synthetically
ii. Can also be found in and extracted from oil of rue – found naturally in bananas, cloves, ginger, guava, strawberries, wild-grown tomatoes, and the perennial Houttuynia cordata
iii. It protects against mosquitoes for about four hours and against ticks for two hours.
iv. It also repels dogs and cats – can be an issue if interacting with them is planned during the trip
v. The American Academy of Pediatrics has made no recommendation on the use in children
I hope some of the information above has helped ease some of the worry on preparing for your trips. Like always – Travel smart and travel safe everyone!