Dengue fever is a viral disease. It's spread by mosquitoes mainly in tropical and subtropical areas of the world. It's rare in the continental U.S. But it's found in some tropical U.S. territories, such as Puerto Rico, Guam, and American Samoa. Dengue fever is most common in:

• South Pacific
• South Central Asia
• Caribbean
• Central and South America
• Africa

Dengue fever happens most often in urban areas. But it may be found in rural areas. The mosquitoes that carry the virus usually pass it on during and shortly after the rainy season. The mosquitoes are most active during the day. They are found near human dwellings, often indoors. About half of the world's population is now at risk for this disease.

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Dengue fever is caused by a virus. A certain type of mosquito (Aedes) passes the virus to people through its bites.

Dengue fever causes a severe flu-like illness. It may look like other diseases, such as the flu or malaria. Symptoms usually begin 4 to 10 days after exposure. The illness usually lasts 2 to 7 days. Symptoms may include:

• Sudden high fever
• Severe headaches
• Pain behind the eyes
• Joint and muscle pain
• Nausea
• Vomiting
• Swollen glands
• Rash that appears 3 to 4 days after the fever starts

A very small portion of people with dengue fever get a severe case. It's called dengue hemorrhagic fever. Symptoms show up as the fever begins to ease. These may include vomiting that does not go away, rapid breathing, blood in vomit, and bleeding gums.

A special blood test can diagnose dengue fever. It can find the virus or antibodies made in response to the virus. See your doctor if you get sick within a month of returning from travel in a tropical area. Your doctor will ask you for your complete travel history. Your doctor can then figure out if your symptoms may be a dengue infection.

Dengue fever is usually treated with supportive care, such as pain relievers, bed rest, and fluids. You may take acetaminophen to lower the fever. But you should not take aspirin, ibuprofen, or any NSAID (nonsteroidal anti-inflammatory drug). In severe cases, you may need medical care right away from doctors familiar with the disease. This can greatly lower the risk of death.

Severe dengue fever can be fatal if not treated right away. Other effects of severe dengue are:

• Severe bleeding
• Breathing problems
• Organ damage

There is an FDA-approved vaccine to prevent dengue fever in travelers. An FDA-approved vaccine is available only for people ages 9 through 16 who have previous dengue fever confirmed by a lab and who live in areas where dengue fever is common.

Travelers should prevent mosquito bites by:

• Using DEET-based insect repellents on the skin and clothing
• Using permethrin sprayed or soaked clothing as the Aedes mosquitoes bite during the daytime hours
• Staying in well-screened or air-conditioned areas

Call your doctor if you have fever within 3 weeks of travelling to an area affected by the disease. Also call your doctor right away if your symptoms get worse or if you have new ones.

• Dengue fever is caused by a virus passed on by the bite of a daytime biting mosquito.
• Dengue fever occurs in tropical and subtropical areas of the world.
• The disease causes a severe flu-like illness. It's generally treated with pain medicine, bed rest, and fluids.
• When traveling to areas that have dengue fever, prevent mosquito bites. Use insect repellents on skin and clothing. Use window and door screens. Do not leave doors propped open. Use air conditioning when possible.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions, especially after office hours and on weekends and holidays.