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Dengue Fever

Dengue is a disease caused by any one of four closely related dengue viruses (DENV 1, DENV 2, DENV 3, or DENV 4). Dengue hemorrhagic fever (DHF) is a more severe form of dengue infection. It can be fatal if unrecognized and not properly treated in a timely manner. DHF is caused by infection with the same viruses that cause dengue fever. Dengue has become a worldwide problem since the 1950s. The Center for Disease Control has an interactive map showing areas of the world that have confirmed the presence of dengue. Dengue cases have been confirmed in the United States. In Alabama, reported cases of dengue have occurred in people who have traveled outside of the state and were infected by a mosquito before returning home.

About Dengue Infection

Dengue is transmitted to people by the bite of a mosquito that is infected with a dengue virus. The most common mosquito vectors of dengue are Aedes aegypti and Aedes albopictus. These are the same mosquitoes that spread Zika and chikungunya. These mosquitoes live closely to humans and lay their eggs in water-holding containers close to human dwellings.

The mosquito becomes infected with dengue virus when it bites a person who has dengue virus in their blood. The person can either have symptoms of dengue fever or dengue hemorrhagic fever (DHF), or they may have no symptoms. After about one week, the mosquito can then transmit the virus while biting a healthy person.

  • Dengue cannot be spread directly from person to person.
  • In rare cases dengue can be transmitted in organ transplants and blood transfusions from infected donors, and possibly by pregnancy (pregnant mother to fetus).
  • Dengue fever and dengue hemorrhagic fever are caused by the same four viruses but differ by severity of symptoms.

1) Dengue fever: The principal symptoms of dengue fever are: high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, and mild bleeding (e.g., nose or gums bleed, easy bruising). Generally, younger children and those with their first dengue infection have a milder illness than older children and adults.

2) Dengue hemorrhagic fever: The principal symptoms of dengue hemorrhagic fever (DHF) are characterized by a fever that lasts from 2 to 7 days, with general signs and symptoms consistent with dengue fever. When the fever declines, symptoms including persistent vomiting, severe abdominal pain, and difficulty breathing may develop. This marks the beginning of a 24- to 48-hour period when the smallest blood vessels (capillaries) become excessively permeable (“leaky”). This may lead to failure of the circulatory system and shock followed by death, if circulatory failure is not corrected. In addition, the patient with DHF has a low platelet count and hemorrhagic manifestations, tendency to bruise easily or other types of skin hemorrhages, bleeding nose or gums, and possibly internal bleeding.


  • There is no vaccine for preventing dengue fever or DHF.
  • There is no specific medication for dengue or DHF.
  • People who believe they have dengue should only use pain relievers with acetaminophen and should not use non-steroidal anti-inflammatory drugs (NSAIDS) for the risk of bleeding (these include Ibuprofen, Naproxen, and aspirin).
  • Getting plenty of rest and staying hydrated are very important.
  • If you have dengue, be careful to prevent mosquito bites to prevent the virus being spread by a mosquito to another person.
  • If a clinical diagnosis is made early, a health care provider can effectively treat DHF with fluid replacement therapy.
  • Generally DHF requires hospitalization.
  • If you or a family member develop the symptoms of dengue virus or DHF, contact your healthcare provider.

Visit the Centers for Disease Control and Prevention (CDC) Traveler’s Health for information on travel notices to dengue endemic destinations.

Detect, Test, and Report

The best preventive measure for residents living in areas infested with Aedes aegypti or Aedes albopictus is to eliminate the places where the mosquito lays her eggs, primarily artificial containers that hold water.

Items that collect rainwater or to store water (for example, plastic containers, 55-gallon drums, buckets, or used automobile tires) should be covered or properly discarded. Pet and animal watering containers and vases with fresh flowers should be emptied and cleaned (to remove eggs) at least once a week. This will eliminate the mosquito eggs and larvae and reduce the number of mosquitoes present in these areas. For more info on how to control mosquitos around your home Vector Control.

Using air conditioning or window and door screens reduces the risk of mosquitoes coming indoors. Proper application of mosquito repellents on exposed skin and clothing decreases the risk of being bitten by mosquitoes. To learn more about insect repellents, visit this Environmental Protection Agency website: Insect Repellent Information from the EPA

To learn more about dengue: CDC Dengue Information

Dengue Fever Resources

For questions or concerns regarding insect-borne disease in Alabama, see the Contact Us page, or email us at

Page last updated: December 7, 2021