Protection against Mosquitoes and Other Arthropods
Note: As of July 18, 2003,
this page has been updated to reflect new information.
Therefore, the text here varies from that available in
the printed version of the 2003-2004 Health Information
for International Travel. |
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Although vaccines or chemoprophylactic drugs are
available against important vector-borne diseases such as yellow
fever and malaria, travelers still should be advised to use repellents
and other general protective measures against biting arthropods.
The effectiveness of malaria chemoprophylaxis is
variable, depending on patterns of resistance and compliance with
medication, and no similar preventive measures exist for other mosquito-borne
diseases such as dengue. For many vector-borne diseases, no specific
preventives are available.
General Preventive Measures
The principal approach to prevention of vector-borne
diseases is avoidance. Tick- and mite-borne infections characteristically
are diseases of “place;” whenever possible, known foci
of disease transmission should be avoided. Although many vector-borne
infections can be prevented by avoiding rural locations, certain
mosquito- and midge-borne arboviral and parasitic infections are
transmitted seasonally, and simple changes in itinerary can greatly
reduce risk for acquiring them.
Travelers should be advised that exposure to arthropod
bites can be minimized by modifying patterns of activity or behavior.
Some vector mosquitoes are most active in twilight periods at dawn
and dusk or in the evening. Avoidance of outdoor activity during
these periods can reduce risk of exposure. Wearing long-sleeved shirts,
long pants, and hats minimizes areas of exposed skin. Shirts should
be tucked in. Repellents applied to clothing, shoes, tents, mosquito
nets, and other gear will enhance protection.
When exposure to ticks or biting insects is a possibility,
travelers should be advised to tuck their pants into their socks
and to wear boots, not sandals. Permethrin-based repellents applied
as directed (see the following section, “Repellents”)
will enhance protection. Travelers should be advised to inspect themselves
and their clothing for ticks, both during outdoor activity and at
the end of the day. Ticks are detected more easily on light-colored
or white clothing. Prompt removal of attached ticks can prevent some
infections.
When accommodations are not adequately screened or
air conditioned, bed nets are essential to provide protection and
comfort. Bed nets should be tucked under mattresses and can be sprayed
with a repellent, such as permethrin. The permethrin will be effective
for several months if the bed net is not washed. Aerosol insecticides
can help clear rooms of mosquitoes.
Repellents
Travelers should be advised that permethrin-containing
repellents (e.g., Permanone or deltamethrin) are recommended for
use on clothing, shoes, bed nets, and camping gear. Permethrin is
highly effective as an insecticide and as a repellent. Permethrin-treated
clothing repels and kills ticks, mosquitoes, and other arthropods
and retains this effect after repeated laundering. There appears
to be little potential for toxicity from permethrin-treated clothing.
The insecticide should be reapplied after every five washings.
Most authorities recommend repellents containing
N,N-diethylmetatoluamide (DEET) as an active ingredient. DEET repels
mosquitoes, ticks, and other arthropods when applied to the skin
or clothing. In general, the more DEET a repellent contains, the
longer time it can protect against mosquito bites. However, there
appears to be no added benefit of concentrations greater than 50%.
A microencapsulated, sustained-release formulation can have a longer
period of activity than liquid formulations at the same concentrations.
Length of protection also varies with ambient temperature, amount
of perspiration, any water exposure, abrasive removal, and other
factors.
No definitive studies have been published about what
concentration of DEET is safe for children. No serious illness has
arisen from use of DEET according the manufacturer’s recommendations.
DEET formulations as high as 50% are recommended for both adults
and children >2 months of age. Lower concentrations are not as
long lasting, offering short-term protection only and necessitating
more frequent reapplication. Repellent products that do not contain
DEET are not likely to offer the same degree of protection from mosquito
bites as products containing DEET. Non-DEET repellents have not necessarily
been as thoroughly studied as DEET and may not be safer for use on
children. Parents should choose the type and concentration of repellent
to be used by taking into account the amount of time that a child
will be outdoors, exposure to mosquitoes, and the risk of mosquito-transmitted
disease in the area. The recommendations for DEET use in pregnant
women do not differ from those for nonpregnant adults.
DEET is toxic when ingested and may cause skin irritation
in sensitive persons. High concentrations applied to skin can cause
blistering. However, because DEET is so widely used, a great deal
of testing has been done, and over the long history of DEET use,
very few confirmed incidents of toxic reactions to DEET have occurred
when the product is used properly.
Travelers should be advised that the possibility
of adverse reactions to DEET will be minimized if they take the following
precautions:
- Use enough repellent to cover exposed skin or clothing. Do not
apply repellent to skin that is under clothing. Heavy application
is not necessary to achieve protection. If repellent is applied to
clothing, wash treated clothing before wearing again.
- Do not apply repellent to cuts, wounds, or irritated skin.
- After returning indoors, wash treated skin with soap and water.
- Do not spray aerosol or pump products in enclosed areas; do not
breathe in.
- Do not apply aerosol or pump products directly to the face. Spray
your hands and then rub them carefully over the face, avoiding eyes
and mouth.
- When using repellent on a child, apply it to your own hands and
then rub them on your child. Avoid the child’s eyes and mouth
and apply sparingly around the ears.
- Do not apply repellent to children’s hands. (Children tend
to put their hands in their mouths.)
- Do not allow children under ten years old to apply insect repellent
to themselves; have an adult do it for them. Keep repellents out
of reach of children.
- Protect infants two months of age and under by using a carrier
draped with mosquito netting with an elastic edge for a tight fit.
- Bed nets, repellents containing DEET, and permethrin should be
purchased before traveling and can be found in hardware, camping,
sporting goods, and military surplus stores. Overseas, permethrin
or another insecticide, deltamethrin, may be purchased to treat bed
nets and clothes.
— Paul
Arguin, Ann Barber, Meghna Desai, Roger Nasci, Monica Parise, Robert
Wirtz
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