What is a dengue fever test?

Dengue fever is a viral infection spread to people through bites from infected mosquitos. You can't catch the virus from a person who is sick with dengue fever.

A dengue fever test checks a sample of your blood to see if you have the virus. The test is used if you have symptoms of dengue fever and have been in an area where mosquitos carry the virus.

The dengue virus is most common in parts of the world with tropical and subtropical climates, including:

• South and Central America
• The Caribbean, including Puerto Rico and the U.S. Virgin Islands
• Asia
• The Middle East
• The Pacific Islands
• Africa

Outbreaks of dengue fever are rare in the U.S. mainland. But small outbreaks have been reported in parts of Florida and Texas.

Most people who get the dengue virus won't become sick. People who do get sick may have mild to severe symptoms that usually begin four to ten days after a bite from an infected mosquito. The most common symptom is a sudden high fever. There is no specific medicine that can cure or treat dengue fever, but most people will recover after about a week.

Some people who get sick with dengue will develop severe dengue disease. Severe dengue can cause internal bleeding and shock, which can be life-threatening.

Infants and pregnant women have a higher risk for developing severe dengue. The risk is also higher for people who have had dengue and then get it again. That's why it's so important to get a dengue fever test if you have symptoms after being in an area where the virus is common.

There are two main types of dengue fever blood tests:

• Antibody tests check your blood sample for proteins, called antibodies, that your immune system makes to fight viruses and other germs. Your body needs time to make specific antibodies to fight dengue. So, these tests are most accurate when they are done four days or more after your symptoms begin.
• Molecular tests look for genetic material from the dengue virus in your blood sample. A PCR test (polymerase chain reaction) is a type of molecular test that's used to check for dengue. These tests can be done during the first seven days after your symptoms begin. Tests done later than that may not have accurate results.

One type of PCR test can check for dengue along with two other viruses that mosquitos carry. These viruses, chikungunya and zika, are common in the same places as the dengue virus, and they cause similar symptoms. Your provider can order this test from your state or local public health department.

Other names: dengue virus antibody, dengue virus by PCR

What is it used for?

A dengue fever test is used to find out if you have the dengue virus. It is mostly used for people who have symptoms related to dengue fever and have recently traveled to an area where dengue infections are common.

Why do I need a dengue fever test?

You may need to be tested for the dengue virus if you have symptoms of dengue fever and have been in an area where the virus is common. Symptoms usually show up four to ten days after being bitten by an infected mosquito.

Symptoms of dengue fever include a sudden high fever (104°F or higher) with any of these other symptoms:

• Nausea and vomiting
• Rash
• Eye pain, typically behind the eyes
• Headache
• Joint, bone or muscle pain

Symptoms of severe dengue may begin 24 to 48 hours after the fever has gone away. Get medical help right away if you or a family member has any of these warning signs of severe dengue:

• Abdominal (belly) pain or tenderness
• Vomiting (at least 3 times in 24 hours)
• Bleeding from the nose or gums
• Vomiting blood or blood in stool (poop)
• Feeling tired, restlessness, or irritable

What happens during a dengue fever test?

Your health care provider will ask about your symptoms and your recent travels. If an infection is suspected, you will get a blood test to check for the dengue virus.

During a blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You don't need any special preparations for a dengue fever test.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

If you had a molecular test (a PCR test):

• A positive test result means that the test found genetic material from the virus in your blood sample. You most likely have a dengue infection.
• A negative test result means that the dengue virus wasn't found in your blood sample. You probably don't have dengue. But it's possible that there wasn't enough virus in your blood sample for the test to find. That might happen if the test was done more than seven days after your symptoms began. If your molecular test result is negative, your provider will usually order an antibody test to confirm that you don't have dengue.

If you had an antibody test, your test results may be reported as positive or negative. Or they may be given as a measurement of the dengue antibodies found in your blood sample.

• A positive test result means that antibodies for the dengue virus were found. You probably have a dengue infection, but you may need another test to confirm the results. That's because the antibody test may have found antibodies that fight other similar viruses that mosquitos carry. Your provider may order another type of blood test to find out exactly which type of viral infection you have.
• A negative test result means that dengue antibodies weren't found in your blood sample. Dengue may not be causing your symptoms. But a negative result could mean that you were tested before your body had time to make enough antibodies to show on the test. So, your provider may order another antibody test to check again.

If you have dengue fever, your provider can tell you how to treat your symptoms. Always follow your provider's instructions. In general, care for dengue fever includes:

• Getting plenty of rest.
• Drinking lots of fluids.
• Taking acetaminophen to control fever and relieve pain. Do not take aspirin, ibuprofen, or naproxen sodium, because they can increase the risk of bleeding.
• Watching carefully for symptoms of severe dengue. Dengue fever can become severe within hours. Get medical help right away if you develop the symptoms of severe dengue.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a dengue fever test?

A vaccine is available for children ages 9 to 16 who:

• Have already had dengue fever. The vaccine helps protect against future dengue infections or from getting severe dengue disease. Before getting the vaccine, a child must have a blood test to confirm a past dengue infection. That's because the vaccine can be harmful to a child who has never had dengue fever.
• Live in areas where dengue is common. These areas include Puerto Rico, the U.S, Virgin Islands, the U.S. territories of American Samoa, the Federated States of Micronesia, the Republic of the Marshall Islands, and the Republic of Palau. The vaccine isn't approved for children traveling to these areas to visit.

If you travel to an area where dengue is common, you can reduce the risk of infection by preventing mosquito bites.