TRAVELERS SHOULD ADVISE THEIR PHYSICIAN OF ANY ACUTE ILLNESS WITH FEVER OCCURRING WITHIN 3 WEEKS AFTER LEAVING A TROPICAL AREA

Aedes Mosquito Dengue is a viral disease transmitted by urban Aedes mosquitos. The principal vector mosquito is Aedes aegypti, a species found living in close association with humans in most tropical urban areas. Mosquito biting activity is greatest in the morning for several hours after daybreak and in the late afternoon for several hours before dark. It may feed all day indoors, in shady areas, or when it is overcast. This mosquito breeds in artificial water containers, such as discarded tires, cans, barrels, buckets, 55 gallon drums, flower vases, and cisterns, all frequently found in the domestic environment. Since 1980, the incidence of dengue has increased dramatically in tropical countries worldwide, with endemic and/or epidemic virus transmission documented in most countries of the Caribbean Basin, Central and South America, the Pacific Islands, Asia, and Africa; many countries have had multiple outbreaks. Epidemics are frequently not reported because of inadequate disease surveillance.

Virus types and distribution

There are four dengue virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4), and all are currently circulating in the Pacific Islands, Americas, Asia, and Africa. In the Americas, all but DEN-3 have widespread distribution. DEN-3 was only recently (October 1994) reintroduced into Central America and is now spreading throughout the region. Since this serotype has been absent from the region for 18 years, there is a low level of immunity and rapid spread is expected.

Risk to the Traveler

The risk of dengue infection for the international traveler appears to be small, unless an epidemic is currently in progress. Current data suggest that the strain of dengue virus, and the age, immune status, and genetic background of the human host are important risk factors for developing DHF. In Asia, children under the age of 15 years who are experiencing a second dengue infection appear to have the highest risk of developing DHF. This suggests that most international travelers from nonendemic areas, such as the United States, have a low risk of developing DHF.

Protection against Dengue

No vaccine is available for dengue, but travelers can protect themselves by using anti-mosquito measures to avoid being bitten.

General recommendations to avoid mosquito bites:

• Apply insect repellent sparingly to exposed skin. An effective repellent will contain 20% to 30% DEET (N,N-diethyl-m-toluamide). DEET in high concentrations (>30%) may cause side effects, particularly in children.
• Avoid formulations containing >30% DEET. Use aerosols in an open space to avoid inhalation. Avoid applying repellent to the hands of children.
• Wear long-sleeved clothing and long pants if you are outdoors during the day and evening.
• Spray permethrin or DEET repellents on clothing, as mosquitos may bite through thin clothing.
• Use mosquito netting over the bed if your bedroom is not air conditioned or screened. For additional protection, treat the mosquito netting with the insecticide permethrin.
• Spray permethrin or a similar insecticide in your bedroom before going to bed.

Note: Vitamin B and ultrasound devices are NOT effective in preventing mosquito bites.

Reduce Your Risk for Infection

Your risk for becoming infected with dengue is lower if you:

• Spend most of your time in air conditioned buildings, hotels, or other closed circulation environments;
• Avoid highly populated residential areas;
• Spend time on beaches or in forested areas.

Think You Have Dengue?

• Avoid analgesics with aspirin; use those with acetaminophen.
• Rest and drink plenty of fluids.
• Consult a physician.