Dengue Fever
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Medically reviewed by Kashif J. Piracha, MD
Dengue fever is a viral infection you can develop after getting bitten by a mosquito infected with the dengue virus. The Aedes species of mosquito spreads the virus. More than half of the world's population—including people in the United States who live in hot, humid climates—are in places where there's a risk of acquiring dengue fever. The risk is highest from August to November.
Many cases of dengue fever are symptom-free or mild, but symptoms can include high fever, headache, body aches, nausea, and rash. Severe cases can be life-threatening and require immediate medical attention.
Dengue fever has been a worldwide problem since the 1960s. In the past two decades, the number of cases reported each year has risen from 500,000 to 5 million. However, mosquitoes are estimated to infect up to 400 million people annually, with 100 million cases causing symptoms. There have been more than 45,000 U.S. cases of dengue fever since 2010, including infections from mosquitoes in the U.S. and infections acquired during travel.
Prevention focuses on controlling mosquitoes and avoiding bites. If you are infected, treatment usually consists of at-home remedies like over-the-counter (OTC) pain relievers.
What's in a Name?
The name dengue comes from the Swahili term Ka-dinga pepo, which means a seizure caused by an evil spirit. Other names for dengue fever include dandy fever, seven-day fever, or breakbone fever (due to its severe joint or bone pains). It may also be simply referred to as dengue.
Dengue Fever Symptoms
About 25% of people infected with the dengue virus will experience symptoms. If symptoms arise, they typically start 4-10 days after infection. The most common symptoms include:
Aches and pains in the muscles, joints, or bones
Eye pain, typically behind the eyes
High fever (104 degrees or above)
Nausea and vomiting
Rash (small pink or red spots or patches)
Severe headache
Swollen glands
About 5% of people will develop severe symptoms, typically 24-48 hours after the fever disappears. Severe symptoms of dengue include:
Abdominal pain and tenderness
Persistent vomiting
Bleeding from the nose or gums
Blood in vomit or stool (poop)
Fatigue, restlessness, or irritability
Rapid breathing
Pale, cold skin
Weakness
What Causes Dengue Fever?
Dengue fever is caused by the dengue virus. Infected mosquitoes transmit the virus to humans through bites. Once someone has been infected with the virus, they can develop dengue fever.
Mosquitoes first acquire the virus after biting a human who's already been infected with the virus. The insect then carries and transmits the virus for the rest of its life.
Although less common, the dengue virus can also spread from a pregnant parent to their child. Rarely, the virus can spread through blood transfusions, breastfeeding, and organ transplants.
It's possible to contract the dengue virus multiple times in your life.
Risk Factors
Aedes mosquitoes are more common in hot, humid climates. If you live in or travel to these areas, it might be more possible that you come into contact with an infected mosquito. In the U.S., cases of dengue have originated in states like Florida, Hawaii, Texas, Arizona, and California. Dengue fever is common in the U.S. territories of Puerto Rico, American Samoa, and the U.S. Virgin Islands.
People who live in urban areas may also be at higher risk for dengue due to crowded living conditions, poor water storage practices, and lack of mosquito population control measures.
Having a history of dengue increases the chances of getting severe dengue.
Young children and pregnant people are at higher risk for severe dengue, making it extra important for these groups to avoid mosquito bites. If you get dengue while pregnant, it can cause the baby to be born too early, be underweight, or have problems with their health before birth.
Editor's Note: Most cases of dengue fever in the U.S. occur in people who have traveled outside of the country. While dengue outbreaks have originated in the U.S., they are small and stay local.
How Is It Diagnosed?
To determine whether you have dengue fever, your healthcare provider will likely first ask questions about your symptoms. Dengue fever can be tricky to diagnose early on because symptoms overlap with malaria, flu, Zika, measles, yellow fever, and preeclampsia (high blood pressure during pregnancy). Blood tests can be ordered to rule out other possible illnesses.
There are two main types of blood tests used to diagnose dengue: antibody and molecular tests.
Antibody tests check your blood for antibodies, which are proteins that fight germs like viruses. Because your body needs time to make the antibodies, it may be best to have this test done four or more days after your symptoms begin to ensure the test can measure the antibodies' presence.
Molecular tests check your blood for genetic material from the dengue virus. A polymerase chain reaction (PCR) test is an example of a molecular test. Molecular tests should be administered within the first week your symptoms begin.
Researchers are also looking into whether accessible diagnostic tests like a complete blood count, or CBC (a standard blood test providers use to measure several factors of your blood) or non-invasive tests like a urine test or saliva swab can help diagnose dengue.
Treatments for Dengue Fever
The goal of treatment is to relieve symptoms and prevent complications. There is no medication specifically made to treat dengue. Instead, treatment involves implementing lifestyle changes and taking medication to manage symptoms.
Most people will get better at home in 1-2 weeks with rest, hydration (drinking plenty of fluids), and Tylenol (acetaminophen). Tylenol can help reduce your fever and any pain. You should not take aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) such as Advil (ibuprofen). These can increase your risk of dengue-associated bleeding.
In severe cases, you may need to stay in the hospital for close monitoring and the administration of intravenous (IV) fluids so you can receive hydration through the vein.
Prevention
To prevent dengue, you must avoid mosquito bites. You should take steps to prevent mosquito bites if you live in or are visiting an area known to have larger populations of Aedes mosquitoes.
To avoid mosquito bites when outside:
Avoid outdoor activities during peak mosquito activity (dawn and dusk)
Burn mosquito coils or use vaporizers containing insect repellents outdoors
Sleep under mosquito nets, ideally treated with repellent
Use personal mosquito repellents
Wear protective clothing that covers your skin
To prevent or get rid of mosquitoes in and around your home:
Eliminate sources of standing water where mosquitoes breed (like in buckets and planters)
Use larvicides (insecticides) in large water containers, and repair any cracks in your septic tank
Use window screens and air conditioning to keep mosquitoes out of your home
Use foggers in high-risk (dark, humid) areas, such as under the sink or in closets, furniture, and the laundry room
A dengue vaccine can help prevent the infection. However, the vaccine is only approved for use in children aged 9-16 who have had dengue before and live where dengue happens frequently or continuously. In the U.S., this would only include certain territories, such as Puerto Rico. The vaccine is not approved for residents of the 50 states visiting an area where dengue is common.
If you plan to travel, consider checking the Centers for Disease Control and Prevention's (CDC) country-specific travel recommendations as well as the travel preparation advice on getting health care abroad.
Complications
In severe cases, dengue fever can lead to life-threatening complications, including hemorrhage (severe bleeding) or shock (when blood pressure drops dangerously low, leading to organ failure).
Warning signs that require immediate medical attention include:
Severe abdominal pain
Persistent vomiting (three or more times in 24 hours)
Bleeding gums or nosebleeds
Vomiting blood or having blood in your stool
Rapid breathing or difficulty breathing
Fatigue or restlessness
Pale, cold, or clammy skin
Severe headache or dizziness
Confusion or irritability
Difficulty waking up or being alert
A Quick Review
Dengue fever is a viral infection that Aedes mosquitoes pass to humans. It can cause a high fever, severe headache, muscle and joint pain, nausea, vomiting, and rash.
While most cases are mild and get better with at-home symptom relief, severe dengue can lead to hospitalization and life-threatening complications. Prevention involves taking measures to control mosquitoes and avoiding mosquito bites.
Frequently Asked Questions
How long are you sick with dengue fever?
Most people with dengue fever get better in 1-2 weeks with at-home care.
How serious is dengue fever?
Most people with dengue fever have mild-to-moderate symptoms and recover at home. However, the illness can be dangerous because it can lead to severe complications, such as bleeding and shock, which can be life-threatening.
How contagious is dengue fever?
Dengue fever does not spread through casual contact between individuals like the cold or flu might. Transmission of the dengue virus occurs through the bite of infected mosquitoes. However, there are rare instances of transmission during breastfeeding or from a blood transfusion.
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