Although
vaccines or chemoprophylactic drugs are available against important
vector-borne diseases such as yellow fever and malaria, there
are none for most other mosquito-borne diseases such as dengue,
and travelers still should avail themselves of repellents and
other general protective measures against arthropods. The effectiveness
of malaria chemoprophylaxis is variable, depending on patterns
of resistance and compliance with medication, and for many vector-borne
diseases, no specific preventatives are available.
General
preventative 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 arbo-viral and parasitic infections
are transmitted around human residences and in urban locations.
Most vector-borne infections are transmitted seasonally and simple
changes in itinerary may greatly reduce risk for acquiring certain
infections.
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 may reduce risk of exposure. Wearing
long-sleeved shirts, long pants and hats will minimize 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 mites are a possibility, pants should be
tucked into socks and boots should be worn; sandals should be
avoided. Permethrin-based repellents applied as directed (see
below) will enhance protection. During outdoor activity and at
the end of the day, travelers should inspect themselves and their
clothing for ticks. Ticks are detected more easily on light colored
or white clothing. Prompt removal of attached ticks may prevent
infection.
When
accommodations are not adequately screened or air-conditioned,
bednets are essential to provide protection and comfort. Bednets
should be tucked under mattresses and can be sprayed with repellent.
Aerosol insecticides and mosquito coils may help to clear rooms
of mosquitoes; however, some coils contain DDT and should be used
with caution.
Repellents
Permethrin-containing repellents (Permanone)* are recommended
for use on clothing, shoes, bednets and camping gear. Permethrin
is highly effective as an insecticide/ acaricide and as a repellent.
Permethrin-treated clothing repels and kills ticks, mosqui-toes
and other arthropods and retains this effect after repeated laundering.
There appears to be little potential for toxicity from permethrin-treated
clothing.
Permethrin-containing
shampoo (Nix)* and cream (Elimite)*, marketed for use against
head lice and scabies infestations, potentially could be extremely
effective as repellents when applied on the hair and skin. However,
they are approved only to treat existing conditions. Most authorities
recommend repellents containing deet (N,N-diethylmeta-toluamide)
as an active ingredient. Deet repels mosquitoes, ticks, and other
arthropods when applied to skin or clothing. Formulations containing
Deet is toxic when ingested. High concentrations applied to skin
may cause blistering. Rare cases of encephalopathy in children,
some fatal, have been reported after cutaneous exposure. Other
neurologic side effects also have been reported. Toxicity did
not appear to be dose-related in many cases and these may have
been idiosyncratic reactions in predisposed individuals. However,
a dose-related effect leading to irritability and im-paired concentration
and memory has been reported. Recommendations and precautions
on the use of repellents are given in Table 24.
TABLE
24. Precautions to Minimize Potential for Adverse Reactions from
Repellents
- Apply
repellent sparingly only to exposed skin or clothing.
- Avoid
applying high-concentration (>30% DEET) products to
the skin, particularly of children.
- Do
not inhale or ingest repellents or get them into the eyes.
- Wear
long sleeves and long pants, when possible, and apply
repellents (e.g., permethrin) to clothing to reduce cutaneous
exposure.
- Avoid
applying repellents to portions of children’s hands
that are likely to have contact with eyes or mouth.
- Pregnant
and nursing women should minimize use of repellents.
- Never
use repellents on wounds or irritated skin.
- Use
repellent sparingly; one application will last approximately
4 hours. Saturation does not increase efficacy.
- Wash
repellent-treated skin after coming indoors.
- If
a suspected reaction to insect repellents occurs, wash
treated skin, and call a physician. Take the repellent
container to the physician.
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†
Use of tradenames is for identification only and does not imply
endorsement by the Public Health Service or the U.S. Department
of Health and Human Services
Reference:
CDC Health Information for International Travel
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