Dengue fever, or breakbone fever, results from a viral infection carried by Aedes mosquitoes. Symptoms include a high fever and body aches. Severe dengue can involve shock and hemorrhagic fever. It can be life-threatening and needs urgent medical treatment.

Four different viruses can cause dengue fever.

Symptoms range of dengue fever from mild to severe. Severe symptoms can indicate dengue shock syndrome (DSS) and dengue hemorrhagic fever (DHF). These require urgent medical attention.

In 2019, the Food and Drug Administration (FDA) approved a vaccine for children ages 9–16 years who have had dengue in the past and live in areas where dengue is common. These areas include some United States territories.

For most people, the best way to prevent dengue fever is to take steps to avoid mosquito bites.

There is no cure for dengue fever. However, early recognition and treatment can help manage symptoms and prevent fatalities.

In 2021, there were 117 cases in the U.S. and 513 cases in all U.S. territories. Some cases were in people who had traveled abroad. However, 509 cases in Puerto Rico were not related to travel.

This article looks at the symptoms and causes of dengue fever and who is at risk.

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Symptoms of dengue fever will depend on the severity of the disease. Around 75% of people with dengue fever will not experience symptoms.

Mild symptoms

If symptoms occur, there may be a sudden fever of around 104°F (40°C) with one or more of the following:

The symptoms typically last between 2–7 days, and most people feel better after one week. The fever may spike, go away for 24 hours, then spike again.

Severe symptoms

Between 0.5% and 5% of cases of dengue fever become severe. If this happens, it can be life threatening.

First, the fever typically falls to 99.5 to 100.4°F (37.5 to 38°C). Severe symptoms may then appear 24–48 hours later, or around 3–7 days after the person starts to feel unwell.

They include:

Anyone with severe symptoms needs immediate medical attention.

Severe signs and symptoms can indicate DSS or DHF. They are potentially fatal.

Here are some images that may help identify dengue fever.

Treatment for dengue involves managing the symptoms.

According to 2009 research, treatment for milder forms includes:

  • drinking water to help prevent dehydration
  • getting plenty of rest
  • using pain relief, such as Tylenol or paracetamol, which can also help reduce fever

Nonsteroidal anti-inflammatory drugs such as aspirin or ibuprofen are not suitable as they can increase the risk of internal bleeding.

In some cases, a doctor may recommend hospitalization and:

Without treatment, 10–20% of severe cases may be fatal. Treatment reduces this figure to 1%.

Four viruses can cause dengue fever. They are all transmitted either by the Aedes aegypti mosquito or, more rarely, the Aedes albopictus mosquito.

These species of mosquitoes live in tropical and subtropical areas around the world, including parts of the U.S. Rates of infection have grown in recent decades, especially in urban areas.

A mosquito carrying the virus passes it to a human by biting them. When another mosquito bites a person with the condition, it will pick up the condition. Then the mosquito will pass the virus on to the next person it bites.

A person can have dengue fever more than once. They will become immune to the specific virus that caused it, though they will not be immune to the other three viruses.

A person is at risk of dengue fever if they live or travel in an area where dengue occurs and mosquitoes that can carry it live.

Dengue occurs in over 100 countries across:

  • North and South America
  • South-East Asia
  • the Pacific Islands
  • Australia
  • Africa
  • the Eastern Mediterranean

Around 70% of cases occur in Asia.

Among U.S. citizens, most cases occur in:

  • Puerto Rico
  • the U.S. Virgin Islands
  • American Samoa

Americans are most likely to contract the infection while traveling. However, local transmission is possible in many parts of the U.S., as the mosquitoes that transmit it live there.

The signs and symptoms of dengue fever are similar to some other diseases such as influenza and malaria. This can make diagnosis challenging.

A doctor will most likely:

  • assess the symptoms
  • ask about the person’s medical and travel history
  • order blood tests to confirm the diagnosis

In May 2019, the FDA approved the first dengue vaccine. It can prevent dengue caused by all four viruses.

It is for people who:

  • are ages 9–16 years
  • have had dengue in the past
  • live in areas where dengue is common, including Puerto Rico, American Samoa, Guam, and the U.S. Virgin Islands

People who are not eligible for the vaccine can lower their risk by taking steps to avoid mosquito bites.

Tips include:

  • wearing clothes that cover the body
  • using mosquito repellents on the body
  • using mosquito nets
  • using window and door screens
  • treating camping gear or clothes with insect repellent before use
  • if possible, avoiding being outside at dawn, dusk, and early evening
  • remove any stagnant water around the home and avoid camping near still water
  • check that drains, plant pots, and other features are not collecting water

What are the best natural mosquito repellents?

Mosquitoes spread the virus that causes dengue fever. Most people do not experience symptoms. However, if they do, the symptoms are often mild. In some cases, dengue fever can be life threatening.

Symptoms include fever, aches and pains, and a rash. A person with more severe symptoms may start vomiting persistently, or experience bleeding from their gums or nose, among other symptoms. Severe dengue needs immediate medical attention.