Dengue fever is an illness spread by the bite of mosquitos infected with one of the dengue viruses. Symptoms are usually flu-like but can worsen to severe dengue (dengue hemorrhagic fever), a life-threatening condition. Getting infected a second time increases your risk of serious symptoms. You can get vaccinated if you’ve already had dengue once.
Dengue fever is an illness you can get from the bite of a mosquito carrying one of four types of dengue virus (DENV). The virus is most commonly found in tropical and subtropical regions, including Central and South America, Africa, parts of Asia and the Pacific Islands.
Dengue isn’t contagious from person to person except when passed from a pregnant person to their child. Symptoms are usually mild with your first infection, but if you get another infection with a different version of DENV, your risk of severe complications goes up.
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Dengue is most commonly found in Central and South America, Africa, parts of Asia and the Pacific Islands. A few parts of the U.S. also have dengue. Those living in or traveling to these regions — more than half the people in the world — are most at risk. Children and those who are elderly are at higher risk for serious illness.
Research estimates that nearly 400 million people get infected with dengue each year, but most (about 80%) have no symptoms.
Yes, you can get immunity to a version of dengue virus once you’ve been infected with it. Because there are at least four versions (strains) of the virus (DENV), this is pretty complicated.
Your immune system has tools it can use to recognize infections and get better at fighting them off. As your body fights a virus, it looks through its toolbox to find out which tool (antibody) it has that can destroy that specific threat.
Antibodies are specific to each harmful invader to your body, fitting to them like a key to a lock. Antibodies grab onto their specific target and your immune system destroys it. Once your body knows how to fight that specific virus, you are unlikely to get sick with it again.
After getting one of the four strains of DENV, you shouldn’t be able to get that one again. But the antibodies for that strain don’t fit other versions quite perfectly. So if you get infected by a different version of DENV later on, it can actually use this imperfect fit to trick your immune system (antibody-dependent enhancement).
The different strain can get caught by the antibody from the first strain you had and get pulled into your cells, but — for reasons not fully understood — it’s not destroyed. It’s then inside your cells without your cells knowing it's harmful. This makes it easier for the virus to infect you and cause more serious illness.
Most dengue infections don’t cause symptoms. If you do have symptoms, high fever (104°F/40°C) is typical, along with:
Dengue fever symptoms start to appear four to 10 days after a mosquito bite and can last three to seven days. About 1 in 20 people sick with dengue will develop severe dengue after their initial symptoms begin to fade.
Severe dengue is a life-threatening worsening of dengue symptoms. Warning signs of severe dengue are usually seen 24 to 48 hours after your fever goes away.
Severe dengue is a medical emergency that can be fatal. If you have dengue or live in an area where dengue is common, go to the nearest ER immediately if you experience any of these symptoms:
Dengue fever is caused by one of four dengue viruses. When a mosquito infected with the dengue virus bites you, the virus can enter your blood and make copies of itself. The virus itself and your immune system’s response can make you feel sick.
The virus can destroy parts of your blood that form clots and give structure to your blood vessels. This, along with certain chemicals that your immune system creates, can make your blood leak out of your vessels and cause internal bleeding. This leads to the life-threatening symptoms of severe dengue.
Dengue is spread by Aedes mosquitos, which also carry viruses like Zika and chikungunya. The mosquitos bites someone with dengue fever and then bites someone else, causing them to become infected.
Dengue fever isn’t contagious directly from one person to another like the flu. The only way to get dengue from another person is if a pregnant person becomes infected. If you’re pregnant and get dengue, you can pass it to your baby during pregnancy or childbirth.
Dengue fever is diagnosed with a blood test. Your healthcare provider will take a sample of blood through a vein and send it to a lab to look for signs of dengue virus. This may also identify which of the four versions you have. Your provider can use a blood test to look for other viruses that cause similar symptoms.
There’s no medicine that treats dengue fever. Your healthcare provider will give you recommendations on how to manage your symptoms and if and when you should go to the ER.
Managing your symptoms is the only way to treat dengue fever. Follow your healthcare provider’s recommendations, which may include:
The two main ways to protect yourself from dengue are through avoiding mosquito bites and vaccination.
The best way to reduce your risk of dengue fever is to protect yourself from mosquito bites:
The dengue vaccine (Dengvaxia™) is recommended only if you’ve already had dengue before. It can reduce your risk of severe dengue (dengue hemorrhagic fever) if you get a different version of the dengue virus in the future.
Getting the vaccine isn’t recommended if you’ve never had dengue before. Because getting infected once with dengue makes you more likely to get sicker if you get another version of the virus (antibody-dependent enhancement), getting vaccinated before having dengue for the first time can increase your risk of severe dengue. Your healthcare provider will do a blood test to check for signs of a previous dengue infection to confirm that you’ve had dengue before getting the vaccine.
Vaccination isn’t available to everyone. For instance, travelers from the U.S. aren’t yet eligible. Check with your healthcare provider to understand whether you’re eligible for dengue vaccination.
Most cases of dengue fever don’t have symptoms or the symptoms are mild, but sometimes you can have a more serious case that requires immediate medical attention.
Initial symptoms of dengue last three to seven days. Most people begin to feel better after this, but some have life-threatening severe dengue that requires treatment in a medical facility.
Most people recover from dengue fever without any lasting complications. If you have symptoms of dengue fever, you have about a 1 in 20 chance of it worsening to severe dengue. If you have severe dengue and are treated immediately at a hospital or medical facility, you have a greater than 99% chance of recovering.
If you’re pregnant and have dengue fever, it can cause miscarriage, low birth weight or premature birth. It’s important to take steps to prevent getting dengue during pregnancy to protect yourself and the developing fetus.
Yes. Because there are at least four versions (strains) of the dengue virus, you can get dengue more than once.
You’ll usually become immune to the first strain you get sick with and can’t get it again. But you can get sick with one of the other three strains after that. In fact, you’re more likely to get severely sick if you get dengue more than once.
If you’ve had dengue before, you’re more likely to become seriously ill if you get a different version of the virus in the future. Consider getting vaccinated and taking additional precautions to protect yourself from mosquito bites, especially if you live in a place where dengue is common.
If you live in or have recently visited an area where dengue is common, contact your healthcare provider if you have any symptoms of dengue. They will give you recommendations on how to take care of yourself and when to seek additional treatment.
If you have any warning signs of severe dengue, even if your initial symptoms have gotten better, go to the nearest emergency room immediately. Severe dengue can become life-threatening very quickly.
No. While only a small percentage of those infected with either disease die from them, malaria is deadlier than dengue worldwide.
Of an estimated 400 million people worldwide who get dengue every year, about 40,000 die from it (about 0.01%). Of an estimated 271 million people worldwide who get malaria every year, about 627,000 die from it (around 0.3%).
It’s important to remember that any disease can be deadlier in some parts of the world than in others. Children in Africa are disproportionately at risk of dying of malaria, whereas people living in Asia are the most affected by dengue.
A note from Cleveland Clinic
Hundreds of millions of people get dengue every year. Even if most cases are mild or even symptomless, the thought of severe dengue can be scary. The word “dengue” may have even come from a word for an evil spirit thought to cause the disease.
Fortunately, you can take steps to reduce your risk of mosquito bites and keep an eye out for the warning signs of severe dengue. If you get sick while traveling, make sure you know where to get emergency medical care. If you get seriously ill with dengue, you’ll most likely recover as long as you get immediate medical treatment.
Last reviewed by a Cleveland Clinic medical professional on 06/06/2022.
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