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Dengue Fever

Dengue (pronounced DENgee) fever is a painful, debilitating mosquito-borne disease caused by any one of four closely related dengue viruses. These viruses are related to the viruses that cause West Nile infection and yellow fever.

An estimated 390 dengue infections occur worldwide each year, with about 96 million resulting in illness. Most cases occur in tropical areas of the world, with the greatest risk occurring in:

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Encephalitis, or inflammation of the brain tissue, is rare, affecting about one in 200,000 people each year in the U.S. When it strikes, it can be very serious, causing personality changes, seizures, weakness, and other symptoms depending on the part of the brain affected. Children, the elderly, and those with a weak immune system are most vulnerable. The disease is usually caused by one of several viral infections, so it's sometimes referred to as viral encephalitis. Many people who have...

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  • The Indian subcontinent
  • Southeast Asia
  • Southern China
  • Taiwan
  • The Pacific Islands
  • The Caribbean (except Cuba and the Cayman Islands)
  • Mexico
  • Africa
  • Central and South America (except Chile, Paraguay, and Argentina)

Most cases in the United States occur in people who contracted the infection while traveling abroad. But the risk is increasing for people living along the Texas-Mexico border and in other parts of the southern United States. In 2009, an outbreak of dengue fever was identified in Key West, Fla.

Dengue fever is transmitted by the bite of an Aedes mosquito infected with a dengue virus. The mosquito becomes infected when it bites a person with dengue virus in their blood. It can’t be spread directly from one person to another person.

Symptoms of Dengue Fever

Symptoms, which usually begin four to six days after infection and last for up to 10 days, may include

Sometimes, symptoms are mild and can be mistaken for those of the flu or another viral infection. Younger children and people who have never had the infection before tend to have milder cases than older children and adults. However, serious problems can develop. These include dengue hemorrhagic fever, a rare complication characterized by high fever, damage to lymph and blood vessels, bleeding from the nose and gums, enlargement of the liver, and failure of the circulatory system. The symptoms may progress to massive bleeding, shock, and death. This is called dengue shock syndrome (DSS).

People with weakened immune systems as well as those with a second or subsequent dengue infection are believed to be at greater risk for developing dengue hemorrhagic fever.

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