DENGUE FEVER

DEFINITION

Dengue (DENG-gay) fever is a disease — ranging from mild to severe — caused by four related viruses spread by a particular species of mosquito. Mild dengue fever causes high fever, rash, and muscle and joint pain. More-severe forms of the disease — dengue hemorrhagic fever and dengue shock syndrome — can additionally cause severe bleeding, a sudden drop in blood pressure (shock) and death.

No specific treatment for dengue fever exists, and most people recover. But if you have a severe form of the disease, you need hospital care.

Millions of cases of dengue infection occur worldwide each year. Most often, dengue fever occurs in urban areas of tropical and subtropical regions. A few cases have been reported in the United States — particularly in Texas, along the border with Mexico, and in Hawaii.

SYMPTOMS

Signs and symptoms of dengue fever vary, depending on the form and severity of the disease.

Dengue fever

With the mild form of the disease, you may experience some or all of these signs and symptoms:

• High fever, up to 105 F (40.6 C)
• A rash over most of your body, which may subside after a couple of days and then reappear
• Severe headache, backache or both
• Pain behind your eyes
• Severe joint and muscle pain
• Nausea and vomiting

Sign and symptoms usually begin about four to seven days after being bitten by a mosquito carrying a dengue virus. Mild dengue fever rarely causes death, and your symptoms will usually subside within a week after starting.

Dengue hemorrhagic fever

More-severe forms of the disease usually begin the same way as the mild form (dengue fever) then become worse after several days.

Dengue hemorrhagic fever — a more severe form of the disease than initial dengue fever — can cause signs and symptoms of dengue fever plus:

• Significant damage to your blood and lymph vessels
• A decrease in the number of blood cells that help your blood clot (platelets)
• Bleeding from the nose and mouth
• Bleeding under the skin, which gives the appearance of bruising
• Death

Dengue shock syndrome — Dengue shock syndrome — the most severe form of the disease — may cause signs and symptoms of mild dengue fever plus:

• Severe abdominal pain
• Frequent vomiting
• Disorientation
• Fluid (plasma) leakage from blood vessels
• Heavy bleeding
• A sudden drop in blood pressure (shock)
• Death

Severe signs and symptoms may appear after your fever has improved. In a small number of cases, people with a severe form of the disease die of it. Modern supportive hospital care decreases this risk.

When to see a doctor

If you have any signs or symptoms of dengue fever, see your doctor. If you've recently traveled to a region in which the disease is known to occur, be sure to inform your doctor.

CAUSES

Dengue fever is caused by any one of four dengue viruses spread by the Aedes aegypti mosquito. These mosquitoes thrive in and near human habitations, where they breed in even the cleanest water.

Mosquitoes transmit the virus back and forth between humans. When a mosquito bites a person infected with a dengue virus, the virus enters the mosquito's bloodstream. It then circulates before settling in the salivary glands. When the infected mosquito then bites another person, the virus enters that person's bloodstream, where it may cause the serious illness.

You can become infected with dengue fever more than once. This happens when you're exposed to a different one of the four dengue viruses from the one to which you were previously exposed. Infection a second time is typically what causes the more severe form of the disease — dengue hemorrhagic fever.

RISK FACTOR

Factors that put you at greater risk of developing dengue fever or a more severe form of the disease include:

• Living or traveling in tropical areas. Being in tropical and subtropical areas around the world — especially in high-risk areas, such as tropical Asia, Central and South America, and the Caribbean — increases your risk of exposure to the virus that causes dengue fever. Dengue virus transmission occurs year-round, although the risk is highest during a recognized dengue fever outbreak.
• Prior infection with a dengue fever virus. Previous infection with a dengue fever virus increases your risk of a more severe form of the disease. This is especially true for children. If you've had dengue fever before, you can get it again if you become infected with another one of the four dengue-causing viruses. Having antibodies to a virus in your blood from a previous infection usually helps protect you. But in the case of dengue fever, it actually increases your risk of severe disease — dengue hemorrhagic fever — if you're infected again.