- Dengue is a viral infection acquired through the bites of mosquitoes carrying the dengue virus.
- Travelers are at highest risk in populated urban and residential areas in most tropical countries.
- Symptoms range from a mild flu-like illness to high fever and rash associated with severe headache and muscle, joint, and back pain.
- Classic dengue is self-limited (average duration: 6 days), but severe fatigue that lasts for weeks or months may ensue. Rarely, severe cases progress to significant hemorrhage and organ damage.
- No vaccine for travelers is available. Prevention includes personal protective measures against mosquito bites.
Dengue is a viral infection acquired through the bites of mosquitoes carrying the dengue virus. Four different types of dengue virus (called serotypes) can cause the disease. Travelers can become infected by any of the serotypes that they have not previously encountered. Infection with one serotype confers protection against that virus for life but does not give protection against subsequent infection with the other serotypes.
Dengue infection is the most common cause of systemic febrile illness in travelers returning from the Caribbean, Latin America, and Southeast Asia. The incidence of dengue is usually higher during warm and humid seasons.
Travelers are at highest risk in populated urban and residential areas in most tropical countries. Infection rates range from 2.9 to 8.0% among travelers with fever who are returning from dengue areas in the tropics.
Humans become infected when bitten by the mosquitoes that carry the dengue virus.
These mosquitoes are associated with the living spaces of humans. Larvae are most frequently found in containers with stagnant water, such as discarded tires, flowerpots, and blocked rain gutters. These mosquitoes will interrupt their feeding at the slightest movement but return quickly to feed on the same or a different human host in the same location.
Unlike malaria-transmitting mosquitoes, dengue-transmitting mosquitoes are daytime feeders with 2 peak times of biting activity: 2-3 hours after dawn and mid-to-late afternoon. This pattern, however, changes to an all-day activity when the mosquitoes are indoors or during overcast days.
All persons in an endemic area who previously have not been exposed to the currently circulating serotype are at risk of acquiring dengue. The risk is higher for those staying in places near stagnant water.
Symptoms of dengue most often appear 2-5 days after exposure (uncommonly, more than 7 days and, rarely, up to 14 days after exposure). Fever that presents more than 14 days after last exposure is not due to dengue. Although mild cases with only flu-like symptoms occur, classic dengue cases present with the sudden onset of high-grade fever, severe muscle, joint, and lower back pain, severe pain behind the bony socket of the eye, nausea, vomiting, and generalized weakness. A subtle diffuse red rash appears in most patients during the initial fever phase, and in some cases, a diffuse bright red rash with scattered clear spots is observed 4-6 days into the recovery phase. In many cases, the fever subsides for a day and then returns. Mild bleeding from the nose, mouth, or under the skin (seen as bruising) may also occur.
Consequences of Infection
Classic dengue is self-limited, with an average total duration of 6 days, but severe fatigue that lasts for weeks or months may ensue.
Severe dengue is indistinguishable from classic dengue in its initial stages. In the period when fever has subsided, severe cases may infrequently progress to significant hemorrhage and organ (kidney, liver, brain) damage. Rarely, hemorrhagic fever or shock may ensue.
Experts have debated whether the risk of developing severe dengue is higher in persons who have been previously infected with a different viral serotype of dengue. The residual immune response from a previous infection is thought to be a contributor in a small percentage (less than 2%) of those who develop severe dengue. Thus, travelers who have already had an episode of dengue fever do not need to avoid future travel.
Need for Medical Assistance
Travelers with persistent fever should be seen by a health care professional when possible to ensure that another serious disease (e.g., malaria) is not present.
Travelers with severe abdominal pain, persistent vomiting, an abrupt change from fever to hypothermia (subnormal body temperature) with profuse sweating, extreme exhaustion, lack of energy, or mental status changes should seek immediate medical attention.
Travelers should avoid using aspirin and other nonsteroidal anti-inflammatory drugs for fever because they prevent formation of blood clots.
There is no dengue vaccine available for travelers. Prevention includes personal protective measures against mosquito bites (see Insect Precautions).
The mosquitoes that transmit dengue are generally day biters. In risk areas, travelers should be especially vigilant in applying repellent during daytime hours, especially during peak biting times in the the early morning and late afternoon. Travelers should also consider treating outer clothing, tents, and sleeping bag liners with permethrin (or another pyrethroid) when traveling in a very high-risk area for dengue or other mosquito-borne diseases.
In addition, containers with stagnant water that can serve as breeding sites for mosquitoes should be removed from the proximity of human habitation whenever possible.