Zika virus has emerged as a disease with growing concerns for pregnant patients, or couples who want to become pregnant. These Frequently Asked Questions (FAQs) help answer common questions about Zika virus based on what is currently known. Please check back for updates to this site as we learn more about Zika virus.
What is Zika virus?
Zika is a virus that is in the same family as yellow fever, dengue, West Nile and Japanese encephalitis viruses. Zika virus seems to mostly attack cells in the nervous system.
How is Zika transmitted?
Zika is most commonly contracted from the bite of an Aedes mosquito. It can also be transmitted sexually through vaginal, anal, and possibly oral sex. A pregnant woman can pass the virus to her fetus in utero. There is the possibility Zika can be passed from blood transfusions, but precautions have been taken to make sure the blood supply is safe.
There is no evidence at this time that Zika virus is transmitted through breast milk.
What are the symptoms of Zika virus?
Most people (80%) do not have any symptoms if they contract Zika virus. Those who do may experience one or more of the following:
- Joint pain
- Eye redness or inflammation
Symptoms usually begin about a week after exposure to the virus and last a few days to a week. If you or your partner experiences these symptoms after visiting an area with active Zika transmission, contact your health care provider right away.
What other problems can Zika virus cause?
Zika virus may cause birth defects if a fetus becomes infected. 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. The range of effects that Zika virus may have on a fetus are still being investigated.
Adults who become infected with Zika may develop a rare neurological complication called Guillain-Barré syndrome. This is a 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 muscle function to be restored.
Am I at risk for getting Zika virus?
You may be at risk for Zika virus if you travel to an area where there is local transmission of Zika. This means the mosquitos 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.
The list of regions where local transmission of Zika has been reported is being updated regularly. It is most common in Central and South America, the Caribbean, and islands in the South Pacific. In the United States, local transmission of Zika has been identified in Puerto Rico and some areas of Florida. Check the CDC website for the complete list of travel advisories.
Could there be local transmission of Zika virus in the San Francisco Bay Area?
It is not known exactly if or when local transmission of Zika will occur in California. The Bay Area does have the two types of Aedes mosquitos that can potentially carry the Zika virus, but there have been no reports of infections from local mosquitos. While it is possible that there will be local transmission, it is expected the response will be swift and that a wide-spread 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, abstain from sexual activity. Use latex condoms to reduce the risk of sexual transmission from a partner that may have been exposed.
How can I prevent mosquito bites?
The mosquitos 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 the directions.
If I traveled, should I get tested for Zika?
If you are pregnant and have traveled to a CDC identified area of Zika transmission, you can be tested. A test called a RT-PCR will check for the virus in your blood and urine if it has been 2 weeks or less since you may have been exposed to Zika. If it has been 2-12 weeks after a possible exposure, we can test to see if your body produced IgM antibodies to the virus. After 12 weeks from the potential exposure, there are no tests currently available to determine if there was Zika exposure in the more distant past, or if a person has immunity.
What if my partner traveled?
You qualify for Zika testing if you are pregnant and have had unprotected sex with a partner who traveled to an identified Zika area. Partners should consult their primary care providers to arrange Zika testing if they experienced symptoms. Testing is currently only done on partners that had Zika symptoms during travel, or within 2 weeks of return from an active Zika area.
My partner traveled. 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 in order to reduce the risk of sexual transmission.
I am not pregnant now, but want to become pregnant. What precautions do I need to take because of Zika virus?
If you wish to become pregnant and have traveled to an area with active Zika transmission, it is recommended women wait 8 weeks before trying to conceive and all men wait 6 months, regardless of whether or not they had symptoms of Zika. 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?
To assess your risk for Zika virus, you will be asked at every UCSF prenatal visit if you or your partner has traveled. If you qualify for testing, we will arrange for labs to check for exposure to Zika virus. A negative test result means you can continue with routine prenatal care, but you will have the option of an additional growth ultrasound at 30-32 weeks gestation.
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 growth ultrasounds every 4 weeks, after your fetus is 20 weeks gestation.
If you test positive for Zika, or your fetus shows signs of abnormalities that may be related to Zika virus exposure, you will be followed by one of our high-risk, Maternal-Fetal Medicine doctors.
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 a fetus becomes infected with Zika virus and why others do not become infected. The most recent research suggests that the rate of infection for a fetus may be between 1% and 13 % if a pregnant woman is infected in the first trimester. It is believed it is less likely a fetus will become infected in the 2nd and 3rd trimesters, but more research is needed before this can be determined.
There is not a specific gestational age at which a fetus shows Zika-related abnormalities. Sometimes the signs of infection do not appear until late in the 2nd trimester or 3rd trimester. Not all fetal abnormalities associated with Zika virus can be detected with an ultrasound examination.
What if I have more questions?
If you are a patient with UCSF Obstetrics, please call our Zika Response Nurse Coordinator for any other questions you have at 415-203-6759.
You can also visit the CDC Mother-To-Baby website (link here) to call, chat, text, or email an expert for more information about Zika virus mother-fetal transmission risks.