Dengue (DENG-gey) fever is a mosquito-borne disease that occurs in tropical and subtropical areas of the world. Mild dengue fever causes a high fever, rash, and muscle and joint pain. A severe form of dengue fever, also called dengue hemorrhagic fever, can cause severe bleeding, a sudden drop in blood pressure (shock) and death.
Millions of cases of dengue infection occur worldwide each year. Dengue fever is most common in Southeast Asia and the western Pacific islands, but the disease has been increasing rapidly in Latin America and the Caribbean.
Researchers are working on dengue fever vaccines. For now the best prevention is to reduce mosquito habitat in areas where dengue fever is common.
Many people, especially children and teens, may experience no signs or symptoms during a mild case of dengue fever. When symptoms do occur, they usually begin four to seven days after you are bitten by an infected mosquito.
Dengue fever causes a high fever — 104 F degrees — and at least two of the following symptoms:
- Muscle, bone and joint pain
- Pain behind the eyes
- Swollen glands
Most people recover within a week or so. In some cases, symptoms worsen and can become life-threatening. Blood vessels often become damaged and leaky. And the number of clot-forming cells (platelets) in your bloodstream drops. This can cause a severe form of dengue fever, called dengue hemorrhagic fever, severe dengue or dengue shock syndrome.
Signs and symptoms of dengue hemorrhagic fever or severe dengue — a life-threatening emergency — include:
- Severe abdominal pain
- Persistent vomiting
- Bleeding from your gums or nose
- Blood in your urine, stools or vomit
- Bleeding under the skin, which might look like bruising
- Difficult or rapid breathing
- Cold or clammy skin (shock)
- Irritability or restlessness
When to see a doctor
Call 911 or go to the nearest emergency room if you've recently visited a region in which dengue fever is known to occur and you develop emergency symptoms, such as severe abdominal pain, vomiting, difficulty breathing, or blood in your nose, gums, vomit or stools.
If you develop a fever and milder symptoms common to dengue fever, call your doctor.
Dengue fever is caused by any one of four types of dengue viruses spread by mosquitoes that thrive in and near human lodgings. When a mosquito bites a person infected with a dengue virus, the virus enters the mosquito. When the infected mosquito then bites another person, the virus enters that person's bloodstream.
After you've recovered from dengue fever, you have immunity to the type of virus that infected you — but not to the other three dengue fever virus types. The risk of developing severe dengue fever, also known as dengue hemorrhagic fever, actually increases if you're infected a second, third or fourth time.
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 increases your risk of exposure to the virus that causes dengue fever. Especially high-risk areas are Southeast Asia, the western Pacific islands, Latin America and the Caribbean.
- Prior infection with a dengue fever virus. Previous infection with a dengue fever virus increases your risk of having severe symptoms if you're infected again.
If severe, dengue fever can damage the lungs, liver or heart. Blood pressure can drop to dangerous levels, causing shock and, in some cases, death.
One dengue fever vaccine, Dengvaxia, is currently approved for use in those ages 9 to 45 who live in areas with a high incidence of dengue fever. The vaccine is given in three doses over the course of 12 months. Dengvaxia prevents dengue infections slightly more than half the time.
The vaccine is approved only for older children because younger vaccinated children appear to be at increased risk of severe dengue fever and hospitalization two years after receiving the vaccine.
The World Health Organization stresses that the vaccine is not an effective tool, on its own, to reduce dengue fever in areas where the illness is common. Controlling the mosquito population and human exposure is still the most critical part of prevention efforts.
So for now, if you're living or traveling in an area where dengue fever is known to be, the best way to avoid dengue fever is to avoid being bitten by mosquitoes that carry the disease.
If you are living or traveling in tropical areas where dengue fever is common, these tips may help reduce your risk of mosquito bites:
- Stay in air-conditioned or well-screened housing. The mosquitoes that carry the dengue viruses are most active from dawn to dusk, but they can also bite at night.
- Wear protective clothing. When you go into mosquito-infested areas, wear a long-sleeved shirt, long pants, socks and shoes.
- Use mosquito repellent. Permethrin can be applied to your clothing, shoes, camping gear and bed netting. You can also buy clothing made with permethrin already in it. For your skin, use a repellent containing at least a 10 percent concentration of DEET.
- Reduce mosquito habitat. The mosquitoes that carry the dengue virus typically live in and around houses, breeding in standing water that can collect in such things as used automobile tires. You can help lower mosquito populations by eliminating habitats where they lay their eggs. At least once a week, empty and clean containers that hold standing water, such as planting containers, animal dishes and flower vases. Keep standing water containers covered between cleanings.
Diagnosing dengue fever can be difficult, because its signs and symptoms can be easily confused with those of other diseases — such as malaria, leptospirosis and typhoid fever.
Your doctor will likely ask about your medical and travel history. Be sure to describe international trips in detail, including the countries you visited and the dates, as well as any contact you may have had with mosquitoes.
Certain laboratory tests can detect evidence of the dengue viruses, but test results usually come back too late to help direct treatment decisions.
No specific treatment for dengue fever exists. Your doctor may recommend that you drink plenty of fluids to avoid dehydration from vomiting and a high fever.
While recovering from dengue fever, watch for signs and symptoms of dehydration. Call your doctor right away if you develop any of the following:
- Decreased urination
- Few or no tears
- Dry mouth or lips
- Lethargy or confusion
- Cold or clammy extremities
Acetaminophen (Tylenol, others) can alleviate pain and reduce fever. Avoid pain relievers that can increase bleeding complications — such as aspirin, ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve, others).
If you have severe dengue fever, you may need:
- Supportive care in a hospital
- Intravenous (IV) fluid and electrolyte replacement
- Blood pressure monitoring
- Transfusion to replace blood loss
Preparing for an appointment
You'll likely start by seeing your primary care provider. But you might also be referred to a doctor who specializes in infectious diseases.
Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be well-prepared for your appointment. Here's some information to help you get ready, and what to expect from your doctor.
What you can do
- Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
- Write down key personal information. List your international travel history, with dates and countries visited and medications taken while traveling. Bring a record of your immunizations, including pre-travel vaccinations.
- Make a list of all your medications. Include any vitamins or supplements you take regularly.
- Write down questions to ask your doctor. Preparing a list of questions can help you make the most of your time with your doctor. List your questions from most important to least important in case time runs out.
For dengue fever, some basic questions to ask your doctor include:
- What's the most likely cause of my symptoms?
- What kinds of tests do I need?
- What treatments are available?
- How long will it be before I'm feeling better?
- Are there any long-term effects of this illness?
- Do you have any brochures or other printed material that I can take home with me? What websites do you recommend?
What to expect from your doctor
Be prepared to answer questions from your doctor, such as:
- When did your symptoms begin?
- Have your symptoms been continuous or occasional?
- How severe are your symptoms?
- Does anything seem to make your symptoms better or worse?
- Where have you traveled in the past month?
- Were you bitten by mosquitoes while traveling?
- Have you been in contact recently with anyone who was ill?