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Dengue Fever

Black and white microscopic image of dengue virus
This transmission electron microscopic (TEM) image depicts a number of round, Dengue virus particles that were revealed in this tissue specimen. (CDC/ Frederick Murphy)

What is dengue?

Dengue is a virus transmitted by the bite of an infected mosquito. It has been found in many parts of the world, including recently the Caribbean, South and Central America, and North America.

What are the signs and symptoms of dengue?

Symptoms of dengue include high fever, severe headache, eye pain, joint pain, muscle pain, rash, and mild bleeding. A more severe form of the disease, dengue hemorrhagic fever, has similar symptoms that are followed by vomiting, severe abdominal pain, and difficulty breathing.

How can I get dengue?

Dengue is spread through the bite of an infected mosquito. It cannot be transmitted directly from person to person.

Can I get dengue in San Mateo County?

Dengue is not currently present among mosquitoes in San Mateo County. However, a species of mosquito capable of transmitting dengue, Aedes aegypti, has been found in San Mateo County recently. Local mosquitoes could become infected by feeding on someone with an active case of dengue. For this reason, the District works closely with the County Health Department on all mosquito-borne disease cases. When a mosquito-borne disease is detected in a patient in San Mateo County, the health department notifies the District. District staff will then conduct mosquito surveillance in the area to ensure that vector mosquitoes are kept at very low numbers.

What can I do if I am traveling to a country where dengue is present?

There is currently no vaccine or medication to prevent infection with dengue. Travelers are advised to avoid mosquito bites. For information on protecting yourself from mosquito bites, see What You Can Do: Mosquitoes.

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