Dengue Fever

What's the Problem?

Dengue is an increasing problem in the Americas and throughout the tropical and subtropical world. It is a disease caused by one of four related viruses (Dengue 1, Dengue 2, Dengue 3 or Dengue 4). Dengue is transmitted to humans by the bite of an infected mosquito. Dengue fever is most common during the rainy season in areas where infected Aedes mosquitoes are present. The symptoms of dengue fever include: sudden onset of fever; painful headaches; eye, joint, and muscle pain; and rash. The symptoms begin 3 to 14 days after the infected mosquito has bitten the person and usually resolve within 1 to 2 weeks. A small number of people experience dengue hemorrhagic fever (DHF), a very serious illness characterized by abnormal internal or external bleeding. If not properly treated, the patient may experience very low blood pressure (shock). DHF can be fatal, particularly in children.

Who's at Risk?

The risk for international travelers is minimal. Children under the age of 15 years who live in countries where dengue is transmitted every year, and who experience a second infection appear to have the highest risk of developing DHF. When traveling to urban tropical areas that have increased dengue fever activity, people should avoid exposure to mosquitoes during their hours of highest activity. Aedes mosquitoes are usually most active during the day and may be found indoors or outdoors. Repellents containing DEET, when used according to label instructions, can be very effective in reducing mosquito-human contact and the risk of contracting the virus.

Can It Be Prevented?

The emphasis for dengue prevention in areas where it is commonly transmitted should focus on sustainable, community-based, integrated mosquito control, with limited reliance on insecticides. Preventing epidemic disease requires a coordinated community effort to increase awareness about dengue, in addition to motivated government officials and community residents to help in controlling the mosquito that transmits it.

The Bottom Line

• Vaccines against dengue are still in development.
• The best preventive measure for residents living in areas infested with Aedes aegypti or Aedes albopictus mosquitoes is to eliminate or control potential breeding places, primarily artificial containers that hold water where the female mosquito lays her eggs.
• Residents need to be responsible for keeping their yards and patios free of sites where mosquitoes can be produced.

Case Example

A 17-year-old girl is taking music class when she starts feeling bad back pain. She tells a classmate she feels weak, dizzy, and has chills. Her mother, Celia, takes her to the doctor but no one suspects she has dengue. The girl is sent home but has to return to the emergency room because she has small skin hemorrhages, rash, nausea, and body pain. She is feeling weaker. She has to be hospitalized because her liver is swollen and her platelet count is low.

Celia notices that a junk car parked in front of the house has accumulated rainwater, and the water has lots of mosquito larvae. Dozens of mosquitoes are flying out of the old car. Celia mentions this to the doctor who now considers dengue hemorrhagic fever as the possible cause of her daughter's illness. With appropriate treatment, her daughter recovers. Next time, the physicians will know to suspect dengue hemorrhagic fever.

Celia, seeking assistance from the local health department, forms a group to spread the word about dengue, and works to mobilize neighbors to conduct "clean up days" twice a month to control potential dengue breeding sites in the neighborhood.