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, known as dengue hemorrhagic fever and dengue shock syndrome.

How is it spread?

Dengue fever is spread through the bite of mosquitoes that carry the virus. 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.

Outbreaks are common in many countries in Latin America and Southeast Asia. The disease also occurs in Africa, parts of the Middle East, the Western Pacific, Puerto Rico, and other tropical and subtropical areas. Travellers visiting these regions may become infected.

Dengue fever is rare in Canada and the continental United States.

What are the symptoms?

Symptoms of dengue fever may be mild or severe. In mild cases, common symptoms include:

• A sudden high fever, up to 41°C (106°F).
• A headache.
• Eye pain.
• Joint and muscle pain.
• A rash.
• Nausea, vomiting, and loss of appetite.

The fever usually lasts up to a week and may come and go.

After the initial fever, some people may have more serious symptoms that may be signs of dengue hemorrhagic fever. These can include:

• Signs of bleeding, such as:
  • Red patches that may look like bruises or tiny red spots.
  • Bleeding from the nose, mouth, or gums.
  • Vomiting blood.
  • Stools that look like black tar.
• Severe belly pain.
• Signs of shock.

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.

Dengue hemorrhagic fever, 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?

People can get the virus more than once. 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:

• Wear protective clothing (long pants and long-sleeved shirts).
• Use insect repellent with DEET or icaridin (Picaridin).
  • 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.
• Spray clothing with an insect repellent containing DEET or icaridin, 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.

The most current information about dengue fever is available from the Government of Canada, the U.S. Centers for Disease Control and Prevention (CDC), and the World Health Organization (WHO). 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 doctor or local health clinic.