Conditions Basics
What is dengue fever?
Dengue (say "DEN-gay") fever is a disease caused by a virus that is carried by mosquitoes. Mild cases cause a rash and flu-like symptoms. Some people, especially children, can get more serious forms of the illness (severe dengue).
How is it spread?
Dengue fever is spread through the bite of mosquitoes that carry the virus. These mosquitoes bite during the day. The biggest risk is at cooler times of the day like sunrise or late in the afternoon. The mosquitoes breed in standing water, usually in cities or towns. The virus cannot spread from person to person through casual contact. People who have dengue fever should be protected from mosquito bites. If a mosquito bites an infected person, the mosquito becomes infected with the virus and can pass it to other people.
Dengue is found throughout the tropics and subtropics. It is widespread throughout Central and South America, Africa, Asia, and Oceania. Dengue outbreaks have happened in southern parts of the United States and Hawaii.
What are the symptoms?
The symptoms most commonly appear 3 to 14 days after a person gets bitten by an infected mosquito. They usually include flu-like symptoms such as:
- High fever.
- Severe headache.
- Pain behind the eyes.
- Joint and muscle pain.
- Nausea and vomiting.
- Rash.
It is common for some people to show no symptoms and most people recover from dengue fever after a few days. In rare cases, people with dengue fever develop severe dengue. Warning signs usually happen 3 to 7 days after the first symptoms, and include a decrease in fever, bleeding from the nose or gums, fatigue, severe abdominal pain, persistent vomiting and trouble breathing.
How is it diagnosed?
Your doctor will ask about your symptoms and any recent travel. The doctor may order a blood test to confirm whether you have dengue fever.
How is dengue fever treated?
There is no medicine for treating dengue fever. Mild cases may be treated at home with rest and plenty of fluids to prevent dehydration. You may take acetaminophen (Tylenol) for pain. But don't take anti-inflammatory medicines like aspirin, ibuprofen (such as Advil or Motrin), or naproxen (such as Aleve). They may increase the risk of bleeding. Be safe with medicines. Read and follow all instructions on the label. People with mild cases of dengue fever usually feel better within 2 weeks.
Severe dengue, the more serious form of dengue fever, usually requires treatment in a hospital. You may need intravenous (IV) fluids to treat dehydration. You also may need a blood transfusion to replace lost blood. You will be closely watched for signs of shock.
How can you prevent it?
There is a vaccine to prevent dengue fever. But the vaccine is only for those who have had dengue fever before. People can get the virus more than once. Avoid areas where dengue fever and mosquitoes are present if you are at higher risk (e.g., are pregnant, very young, or very old). If you plan to travel to an area where dengue fever is common, make sure to protect yourself against mosquito bites. Here are some guidelines:
- Use insect repellent with 20-30% DEET or 20% icaridin (Picaridin).
- Children ages 6 months to 12 years should use products with icaridin instead of DEET.
- The Committee to Advise on Tropical Medicine and Travel (CATMAT) recommends that children younger than age 6 months use 10% icaridin when travelling in areas where the risk of dengue fever infection is high.
- You can buy DEET in Canada at strengths up to 30%. It is available in greater strengths in other parts of the world. But using strengths greater than 50% does not significantly increase protection. DEET is not recommended for use on children younger than 6 months. For older children up to age 12 years, use the lowest concentration available (10%).
- You can buy icaridin (Picaridin) in Canada at strengths up to 20%. Icaridin is not recommended for use on children younger than 6 months.
- Always be careful when using insect repellents, especially on children. Be sure to read and follow the directions on the label.
- The mosquitoes that transmit dengue fever bite during the day, so you need to use repellents whenever you are outside. Spray clothing with an insect repellent because mosquitoes may bite through thin clothing. (Be aware that DEET can damage plastic items, such as watch crystals or eyeglass frames, and some synthetic fabrics.) Icaridin is less likely to cause skin irritation than DEET and does not damage synthetic fabrics or plastics.
- Sleep under bed nets (mosquito netting) treated with an insecticide such as permethrin or deltamethrin.
- Use flying-insect spray indoors around sleeping areas.
If you are planning international travel, you can learn about the risk of dengue fever in the area you're travelling to by contacting:
- The Government of Canada at its website. https://travel.gc.ca/travelling/health-safety/diseases/dengue
- The U.S. CDC at its website. www.cdc.gov/dengue
- Your local travel clinic.
