Frequently Asked Questions About Zika Virus

What other problems can Zika virus cause?

Zika virus may cause birth defects in a developing fetus. The virus can prevent normal brain development and may cause microcephaly, which is an abnormally small head size. Zika infection of a fetus may also lead to hearing, vision, cognitive and developmental disorders.

Scientists are still investigating the range of effects that Zika virus may have on a fetus.

Adults who become infected with Zika may develop a rare condition called Guillain-Barré syndrome. The condition that can cause temporary paralysis and may be severe enough to require extended time in the hospital with breathing support. Most people recover, but it can take several months for them to regain muscle function.

Am I at risk for getting Zika virus?

You may be at risk for Zika if you travel to an area where there is local transmission of the virus. This means mosquitoes in the area may be carrying the Zika virus and are capable of passing it to people when they bite. There may also be a risk if you have unprotected sex with a partner who has traveled to a Zika area.

Since their height in 2016-2017, Zika outbreaks have come and gone in different countries. The virus is most common in Central and South America, the Caribbean and parts of Africa and Southeast Asia. As of 2025, there have been no reported cases in the U.S. of Zika virus transmission by mosquitos since 2019 and rates of infection around the world have been generally low. Check the CDC or the World Health Organization for travel advisories.

Could there be local transmission of Zika virus in the San Francisco Bay Area?

The Bay Area does have the two types of Aedes mosquitoes that can potentially carry the Zika virus, but there have been no reports of infections from local mosquitoes. While it is possible that there will be local transmission, a widespread outbreak is very unlikely.

How can I prevent Zika virus?

There currently is no vaccine to prevent Zika virus and there are no known treatments. The best way to prevent Zika virus is to avoid mosquito bites.

To prevent the possibility of sexual transmission, follow safe sex practices. Use latex condoms to reduce the risk of sexual transmission from a partner who may have been exposed to the virus.

How can I prevent mosquito bites?

The mosquitoes that spread Zika virus bite both during the day and at night. When traveling or during mosquito season:

• Wear pants and long sleeves.
• Stay in air-conditioned areas or use window screens.
• Apply mosquito repellent that is regulated by the Environmental Protection Agency (EPA). EPA-regulated repellents are safe when used as directed and their effectiveness has been studied.

The active ingredients in most EPA-regulated repellents are: DEET; Picaridin; IR3535; or oil of lemon eucalyptus. The percentage of DEET determines how long the repellent lasts, not its effectiveness. Always reapply mosquito repellent according to the directions on the package.

If I traveled, should I get tested for Zika?

If you have traveled to an area of Zika risk, you can be tested.

A test called an RT-PCR will check for genetic material from the virus in your blood and urine if it has been two weeks or less since you may have been exposed to Zika. If two to 12 weeks have passed since a possible exposure, we can perform an antibody test to see if your blood contains antibodies to the virus.

There are no tests currently available to determine if there was Zika exposure more than 12 weeks in the past, or if a person has immunity.

What if my partner traveled?

Partners should consult their primary care providers to discuss their risk and arrange testing if they experienced Zika symptoms.

My partner traveled but did not have symptoms. Do I need to take any precautions?

If your partner traveled to a Zika area and you are pregnant, it is recommended that you abstain from sex to avoid sexual transmission, or use latex condoms for the duration of the pregnancy to reduce the risk of sexual transmission.

I am not pregnant now but want to become pregnant. What precautions do I need to take?

If you wish to become pregnant and have traveled to an area with active Zika transmission, it is recommended that you wait eight weeks before trying to conceive, regardless of whether you had symptoms of Zika or not. If your partner traveled to a Zika area, the recommendation is to wait six months before trying to conceive. This is because the virus is known to live longer in semen, and there is a risk that men who were exposed to Zika could sexually transmit the virus for a longer period of time.

How will my prenatal care be different if there is the possibility I was exposed to Zika virus?

As part of your prenatal care, we will ask if you or your partner has traveled to a Zika area. If the answer is yes, we will arrange for Zika testing. A negative antibody test result means you can continue with routine prenatal care, and no further follow-up related to Zika is necessary.

If you may have been exposed to Zika virus, but it has been more than 12 weeks since you or your partner returned from travel, we can conduct periodic ultrasounds after 20 weeks gestation to assess fetal growth. If you test positive for Zika, or your fetus shows signs of abnormalities that may be related to Zika-virus exposure, one of our high-risk, maternal-fetal medicine doctors will follow your care.

If I test positive for Zika, what are the chances my fetus is infected and when will I know?

There is a lot we do not know about why some fetuses become infected with Zika virus and why others do not. The most recent research suggests that the rate of infection for a fetus may be between 1 and 13 percent if a pregnant woman is infected in the first trimester. Researchers currently believe it is less likely a fetus will become infected in the second and third trimesters, but more research is needed before this can be determined.

There is no specific gestational age at which a fetus shows Zika-related abnormalities. Sometimes the signs of infection do not appear until late in the second or third trimester. Not all fetal abnormalities associated with Zika virus can be detected with an ultrasound examination.

For more information, talk to your provider. You can also visit MotherToBaby, a service of Organization of Teratology Information Specialists (OTIS), (experts in birth defects).