Dengue Fever: Symptoms, Diagnosis and Prevention

Dengue is a mosquito-borne illness found in tropical and subtropical areas. Most people recover, but some develop a severe form that needs hospital care. This article explains what dengue is, the symptoms, how it is diagnosed, what care involves and how to lower your risk.

What is dengue?

According to the WHO, dengue is a viral infection caused by the dengue virus and passed to people through the bite of infected mosquitoes, mainly Aedes aegypti. It is most common in tropical and subtropical areas, often in towns and cities. The WHO says people can pass the virus to mosquitoes from about 2 days before symptoms start to about 2 days after the fever ends.

Common symptoms

The WHO says most infections cause no symptoms or only mild ones, and settle in 1 to 2 weeks. When symptoms appear, they usually start 4 to 10 days after infection and last 2 to 7 days. They can include:

• High fever
• Severe headache
• Pain behind the eyes
• Muscle and joint pain
• Nausea and vomiting
• Swollen glands
• A rash

The CDC says fever is the most common sign and that mild dengue can look like other fever illnesses. The WHO notes tiredness can last for several weeks after recovery, and that a second dengue infection raises the chance of severe dengue.

How dengue is diagnosed

The CDC says a blood test is the only way to confirm dengue, and that doctors may also test for similar viruses such as Zika or chikungunya. The WHO says tests include molecular tests, antibody tests and rapid tests, and that the type of test that works best depends on how many days you have been ill. If you have a fever and live in, or have recently travelled to, an area with dengue, see a doctor rather than guessing.

What care involves

The WHO says there is no specific antiviral treatment for dengue. Care focuses on managing pain and fever, and people with severe dengue often need hospital care. The WHO warns that ibuprofen and aspirin can increase the risk of bleeding, so do not take any painkiller for a suspected dengue fever without asking a doctor which one is safe. Resting and drinking fluids are sensible, and a doctor will guide you.

Preventing dengue

The WHO suggests protection in two ways. For personal protection:

• Wear clothing that covers as much skin as possible
• Use nets, ideally treated, if you sleep during the day, and fit window screens
• Use repellents containing DEET, picaridin or IR3535

For breeding control at home and in the community:

• Remove or cover containers that hold water
• Empty, cover and clean household water storage weekly
• Dispose of solid waste properly

The WHO says a vaccine is licensed in some countries but is recommended only for people aged 6 to 16 in high-transmission settings. A doctor can tell you whether it is available or suitable.

When to see a doctor

See a doctor if you have a fever with the symptoms above, especially in an area with dengue. The CDC says severe dengue is a medical emergency and can develop within hours. Warning signs often appear after the fever goes down and include severe stomach pain, repeated vomiting, rapid breathing, bleeding from the nose or gums, blood in vomit or stool, restlessness, and extreme tiredness or weakness. The WHO advises seeking care immediately if these appear.

In an emergency, call your local emergency number (112 in India, 911 in the United States).

This article is for education only and cannot diagnose dengue.