Zika Testing

Who should be tested for Zika?

YES:

  • Anyone (including pregnant women) with possible exposure to Zika who has symptoms of Zika virus (fever, rash, headache, joint pain, conjunctivitis [red eyes] or muscle pain)
  • Pregnant women who live in or frequently travel to areas with a risk of Zika
  • Pregnant women with possible exposure to Zika whose ultrasound shows that her developing baby might have Zika-related birth defects

MAYBE:

  • Pregnant women with possible exposure to Zika (such as travel or unprotected sex with a partner who recently traveled to an area with Zika) who do not have symptoms. Testing is not routinely recommended, but women and their healthcare providers can decide on a case by case basis if testing might be helpful.

NO:

  • Anyone who is not pregnant and does not have symptoms, even if they had possible exposure to Zika
  • Testing is not the best way to know if it is safe to become pregnant. If you might have been exposed, you should still wait the recommended time before trying to conceive a pregnancy, even if you have a negative Zika test.
  • Testing is not the best way to know if you could pass the virus to someone else through sex. If you might have been exposed, you should still take steps to prevent passing Zika to your sex partners, even if you have a negative Zika test on blood or urine. There is no lab test available to look for Zika in the semen.

These charts can help healthcare providers make decisions about testing for Zika:

What are the different Zika tests?

Zika Nucleic Acid Amplification Test (NAAT) (also called molecular test) looks for the Zika virus in the blood, urine, or other body fluids. NAAT testing for dengue (a related virus) might be done at the same time as the Zika test.

When is Zika NAAT testing done?

  • In non-pregnant people, NAAT testing is done within 7 days of when Zika symptoms started.
  • In pregnant women with possible exposure to Zika, the timing of testing depends on the situation:


What do my Zika NAAT test results mean?

  • A positive NAAT test for Zika usually means that you have Zika virus, and no other testing is needed. However, sometimes the test may need to be repeated to rule out a false positive.
  • A negative NAAT test doesn’t necessarily mean that you don’t have Zika virus; it might just mean that the window of time to detect the virus in the body has already passed. In this case, antibody testing is usually recommended as a second step to rule out Zika infection. Antibody testing looks for Zika antibodies that are still present after the virus is gone from the body (see Antibody Test below).

Zika Antibody Test (also called IgM or serology test) looks for proteins called antibodies that the body makes to fight a Zika infection. These antibodies can be detected for some time after a Zika infection passes. Zika antibody testing is usually performed on the blood or, less frequently, on fluid taken from the spinal column (cerebrospinal fluid). Antibody testing for dengue (a related virus) might be done at the same time as the Zika test.

When is Zika antibody testing done?

  • In non-pregnant people, antibody testing is done if more than 7 days have passed since Zika symptoms started, or as a second step to rule out Zika after getting a negative NAAT test result (see information about negative NAAT test results above).
  • In pregnant women with possible exposure to Zika, antibody testing is performed as follows:

What do my Zika antibody test results mean?

  • A negative Zika antibody test (along with a negative NAAT test, if performed) usually means there is no evidence of Zika virus infection and no need for further testing.
  • A positive or unclear Zika antibody test might need to be confirmed by another test called a Plaque Reduction Neutralization Test (PRNT). The PRNT test helps find out if the antibodies you have are actually from Zika virus, or if they are from another related virus (like dengue). Sometimes, PRNT testing cannot determine if the antibodies you have are from Zika or from another related virus.

Limitations of antibody testing:

Zika antibodies can be detected in some people’s bodies for longer than in other’s. For this reason, a positive antibody test might not be able to tell how long ago you were infected with Zika. For people who had only one possible exposure to Zika (for example, a recent trip to an area with Zika), the timing of that trip might help them know when they were infected. But for people with more than one possible exposure or ongoing exposure, a positive antibody test cannot tell them when the infection happened.

Another limitation to antibody testing is that even a very good test can result in a high number of “false positives” in areas where there is not widespread Zika transmission. Since many areas with Zika are seeing fewer and fewer cases, the usefulness of antibody testing has also decreased. For this reason, antibody testing is not routinely recommended for people who have not had symptoms of Zika, even if they are pregnant. See Zika Virus Testing for Pregnant Women without Symptoms for more information.

Where can I get tested for Zika virus?

Testing is available through commercial (private) laboratories, many state health departments, and the Centers for Disease Control and Prevention. Your healthcare provider can contact your state or local health department for testing information.

Some private labs have information about Zika testing on their websites including:

When will I get my test results?

Turnaround time for test results varies based on the kind of test, where it is being done, and other factors. If the CDC performs the test, it generally takes about 3 weeks to get the results back to your healthcare provider. If a different lab performs the test, this turnaround time might be longer or shorter.