What is dengue?

Dengue is a mosquito-borne disease caused by any one of four closely related dengue viruses (DENV-1, DENV-2, DENV-3, and DENV-4).

Where does dengue occur?

Dengue occurs in many tropical and sub-tropical areas of the world, particularly sub-Saharan Africa, the Middle East, Southeast Asia, and Central and South America. With the exception of Mexico, Puerto Rico, small areas in southern Texas and southern Florida, and some regions of Hawaii, dengue transmission does not occur in North America. Worldwide there are an estimated 50 to 100 million cases of dengue per year.

How do people get dengue?

People get dengue from the bite of an infected mosquito. The mosquito becomes infected when it bites a person who has dengue virus in their blood. It takes a week or more for the dengue organisms to mature in the mosquito; then the mosquito can transmit the virus to another person when it bites. Dengue is transmitted principally by Aedes aegypti(yellow fever mosquito) and Aedes albopictus (Asian tiger mosquito). These mosquitoes are not native to California, but infestations have been identified in multiple counties in California. Dengue virus cannot be transmitted from person to person.

What are the symptoms of dengue?

There are two types of illness that can result from infection with a dengue virus: dengue and severe dengue.

• The main symptoms of dengue are high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, bruising, and may include mild bleeding from the nose or mouth.
• Generally, younger children and those with their first dengue infection have a milder illness than older children and adults.
• Severe dengue typically begins with signs and symptoms similar to dengue. Rather than recover, severe dengue patients proceed to experience more bleeding, severe pain in the abdomen, respiratory distress, and fluid accumulation in the abdomen and around the lungs, as the smallest blood vessels (capillaries) begin to leak. If not treated, severe dengue can result in death.

How is dengue treated?

There is no specific treatment for dengue infection. Rest and fluids are generally sufficient for persons with dengue. Severe dengue may require hospitalization and intensive medical care.

What can people do to keep from getting dengue?

There is no vaccine to prevent dengue. Travelers to areas with active dengue transmission should take proactive measures against mosquito bites. 

• Screens on windows and doors should be examined to confirm that they are in good repair.
• Consider the use of a bed net at night.
• Check screens on doors and windows to make sure there are no tears or holes.
• Apply a repellent containing 20% to 30% DEET  to exposed skin and clothing to keep mosquitoes from biting. 

Always check the Centers for Disease Control and Prevention Travelers' Health website for information regarding mosquito-borne disease transmission when planning a trip.

Where can I find more information about dengue?

Visit the California Department of Public Health’s Aedes aegypti and Aedes albopictus website

 Visit the U.S. Centers for Disease Control and Prevention dengue website