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Questions and Answers for Healthcare Providers Caring for Pregnant Women and Women of Reproductive Age with Possible Zika Virus Exposure

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Summary

CDC has updated its interim guidelines for US health care providers caring for pregnant women and women of reproductive age during active Zika virus transmission. These guidelines apply to health care providers caring for women of reproductive age in the United States including US territories and will be updated as more information becomes available.

What is different in these updated guidelines?

CDC updated its guidelines for women of reproductive age to provide recommendations for women and couples who want to get pregnant. The updated guidelines also include recommendations for Zika virus testing and guidance for women residing along the US-Mexico Border. The new recommendations for people who want to get pregnant depend on individual circumstances. The guidelines include recommendations for couples trying to conceive with: men and women with possible exposure to Zika virus who do not have symptoms, and men and women who have Zika virus disease

Why is CDC updating clinical guidelines?

CDC continues to evaluate all available evidence and to update recommendations as new information becomes available. CDC’s updated guidelines have been informed by our close collaboration with clinicians, professional organizations, state and local health departments, and many other stakeholders.

CDC and state and local health departments have received numerous inquiries from healthcare providers who have requested information on how to counsel patients regarding timing of conception following possible Zika virus exposure or Zika virus disease. CDC has developed updated interim guidelines to address these concerns and will continue to provide updates as more is learned about Zika virus.

General Questions

What is Zika virus?

Zika virus is a mosquito-borne single-stranded RNA virus related to dengue virus. In the Americas, Zika virus is primarily transmitted by Aedes aegypti, but Aedes albopictus mosquitoes can also transmit the virus.

How is Zika virus transmitted?

Zika virus is transmitted to humans primarily through the bite of an infected Aedes species mosquito. Aedes mosquitoes are aggressive daytime biters and feed both indoors and outdoors. They can also bite at night. Zika virus can be transmitted from a pregnant mother to her fetus during pregnancy or around the time of birth. We do not know how often Zika perinatal transmission occurs. Sexual transmission of Zika virus has been documented.

Who is at risk of being infected?

Persons living in or traveling to an area with Zika who have not already been infected with Zika virus are at greatest risk of infection. Specific areas where Zika virus transmission is active are often difficult to determine and are likely to change over time. Please visit CDC’s Zika Travel Information webpage for the most updated information.

In addition, individuals who have had sex without a condom (vaginal intercourse, anal intercourse, or fellatio) with a man who traveled to or resided in an area with Zika are at risk for Zika virus infection.

What is the potential for Zika virus to spread to the United States?

Currently, active mosquito-borne Zika virus transmission has not been reported in the 50 United States, but has been reported in US territories. With the current outbreak in the Americas, the number of cases among US travelers is expected to increase. As the number of returning travelers with Zika virus disease increases, viral introduction and local spread in the US may occur. As more information becomes available, CDC will provide updates on its Zika website.

What are symptoms of Zika virus infection?

Most people infected with Zika virus will not have symptoms. For those with symptoms, characteristic clinical findings are acute onset of fever, macular or papular rash, arthralgia, or conjunctivitis. Other commonly reported symptoms include myalgia and headache. Clinical illness is usually mild with symptoms lasting for several days to a week.

What other complications have been associated with Zika virus infection?

There have been cases of Guillain-Barré syndrome reported in patients following suspected Zika virus infection. The relationship between Zika virus infection and Guillain-Barré syndrome is being studied.

How can Zika virus infection be prevented?

There is no vaccine to prevent Zika virus infection. People at risk for Zika can protect themselves by taking steps to prevent mosquito bites. Use insect repellent; wear long-sleeved shirts and pants; and stay in places with air conditioning or with window and door screens. Pregnant women can and should choose an Environmental Protection Agency (EPA)-registered insect repellent and use it according to the product label. Given the potential risks of maternal Zika virus infection, pregnant women whose male partners have or are at risk for Zika virus infection should use condoms or abstain from sexual intercourse for the duration of the pregnancy.

Are there any special precautions for pregnant women on the use of insect repellents?

EPA-registered insect repellents containing ingredients such as DEET, picaridin, and IR3535 are safe for use during pregnancy when used in accordance with the product label.

Sexual Transmission

Is there a risk of a male partner transmitting Zika virus sexually to a pregnant woman?

Sexual transmission of Zika virus can occur, although there is limited data about the risk. In known cases of sexual transmission, the men had Zika virus symptoms. From these cases, we know the virus can be spread when the man has symptoms, before symptoms start, and after symptoms resolve. In addition, the virus can be present in the semen after it has cleared from the blood. The risk for sexual transmission of Zika virus can be eliminated by abstinence and reduced by correct and consistent use of condoms.

How should pregnant women with male partners with Zika virus infection or at risk for Zika virus infection be counseled?

Given the potential risks of maternal Zika virus infection, pregnant women whose male partners have or are at risk for Zika virus infection should be counseled to use condoms every time they have vaginal, anal, or oral (mouth-to-penis) sex or abstain from sex for the duration of pregnancy.

How long after symptom onset has Zika virus been detected in semen?

Data on Zika virus duration and pattern of persistence in semen is limited. Infectious Zika virus has been detected in semen in two men at least 2 weeks after symptom onset. Further testing in these cases was not performed to determine when Zika virus RNA was no longer present. There has been a third report detected Zika virus RNA 62 days after symptom onset. Infectious Zika virus has been detected in two men at least 2 weeks after symptom onset.

Why does CDC recommend that men with possible or confirmed Zika virus exposure use condoms or abstain from sex with their pregnant partner for the duration of pregnancy?

CDC is recommending either abstaining from sex or using condoms for the duration of the pregnancy. This course is the best way to avoid even a minimal risk of sexual transmission of Zika virus. Zika virus infection in pregnancy has been associated with incomplete brain development and other brain problems, impaired growth, and vision and hearing problems.

When a woman is pregnant, extra precaution is warranted because of the potential for serious birth defects with Zika virus infection during pregnancy. 

Why is CDC recommending that men with confirmed or possible Zika exposure wait 6 months to attempt conception?

The risk of a man transmitting Zika virus to a woman through sex after 6 months from the time his symptoms first appeared is believed to be small, although the level of risk will not be clear until studies currently underway are completed. For couples that desire pregnancy, a minimal risk might be acceptable in order to become pregnant.

Laboratory Testing

What types of testing for Zika virus are available to test pregnant women?

During the first week of illness, Zika virus disease can often be diagnosed by performing reverse transcriptase-polymerase chain reaction (RT-PCR) on serum. Serology assays can also be used to detect Zika virus-specific IgM and neutralizing antibodies, which typically develop toward the end of the first week of illness. Plaque-reduction neutralization testing (PRNT) can be performed to measure virus-specific neutralizing antibodies to confirm primary flavivirus infection and differentiate Zika from other similar illnesses.

Is an immunoglobulin G (IgG) test for Zika virus commercially available?

No. There is currently no commercially available, FDA-cleared test.

How is Zika virus infection diagnosed in pregnant women?

Zika virus infection can be diagnosed by finding Zika virus RNA detected by RT-PCR in any clinical specimen; or Zika virus IgM with confirmatory neutralizing antibody titers that are ≥4-fold higher than dengue virus neutralizing antibody titers in serum by PRNT. Testing would be considered inconclusive if Zika virus neutralizing antibody titers are <4-fold higher than dengue virus neutralizing antibody titers.

What are the challenges in interpreting Zika virus testing?

RT-PCR test may not demonstrate Zika virus RNA in a woman with Zika virus infection if the period of viremia has passed. Serum serologic testing can be performed, however, cross-reactivity with related flaviviruses (e.g., dengue and yellow fever viruses) is common. Plaque-reduction neutralization testing (PRNT) can be performed to measure virus-specific neutralizing antibodies to Zika virus, but neutralizing antibodies may still yield cross-reactive results in persons who were previously infected with another flavivirus, such as dengue, or has been vaccinated against yellow fever or Japanese encephalitis. It is important to work closely with your state or local health department to ensure the appropriate test is ordered and interpreted correctly.

Does a positive Zika virus IgM always indicate Zika virus infection?

No; a positive IgM result can be difficult to interpret since cross-reactivity can occur with related flaviviruses (e.g., dengue, Japanese encephalitis, West Nile, yellow fever). A positive Zika virus IgM result may reflect: previous vaccination against a flavivirus (e.g., yellow fever); previous infection with a related flavivirus; or recent or current infection with a flavivirus, including Zika virus.

What does a negative Zika virus IgM mean?

A negative (IgM) result suggests that infection did not occur and could obviate the need for serial ultrasounds during pregnancy when testing is performed 2 to 12 weeks after travel to areas of active Zika virus transmission. However, data on the performance of IgM serologic testing in asymptomatic persons is limited.  This information is based on experience with other flaviviruses.

Does a negative Zika virus RT-PCR always rule out Zika virus infection?

No. During the first 7 days of symptom onset, viral RNA can often be identified in serum, and RT-PCR is the preferred test. However, viremia decreases over time, and a negative RT-PCR on serum collected 5-7 days after symptom onset does not preclude Zika virus infection. Serologic testing should be performed.

What specimens can be tested for Zika virus?

Zika virus RT-PCR and serology assays can be performed on maternal serum or plasma. Zika virus RT-PCR can also be performed on amniotic fluid. Other testing that can be performed includes the following: 1) histopathologic examination and immunohistochemical staining of the placenta and umbilical cord, 2) Zika virus testing of frozen placental tissue and cord tissue, and 3) IgM and neutralizing antibody testing of cord blood.

What should providers consider when ordering a test for Zika virus infection?

Each clinical scenario is unique, and health care providers should consider all available information when ordering a test for Zika virus infection, including patient travel history or possible exposure through sexual contact, history of flavivirus infection, vaccination history, ultrasound findings, and the presence of symptoms. Providers should work with their state, local, and territorial health departments for assistance obtaining and interpreting test results.

How can providers order a Zika virus test for a patient who has traveled to an area with active Zika virus transmission?

There are no commercially available tests for Zika virus, although the FDA has issued an Emergency Use Authorization (EUA) for the ZIKA MAC-ELISA test for use in qualified laboratories. Zika virus testing is performed at the CDC Arbovirus Diagnostic Laboratory and at various state health departments. Health care providers should contact their state and local health department to facilitate testing. See the Diagnostic Testing webpage for information on how to obtain Zika testing.

What are the recommendations for Zika virus testing of men or women attempting conception?

Testing for Zika virus infection should be performed on persons with possible exposure to Zika virus with one or more of the following symptoms during travel or within 2 weeks of possible exposure: acute onset of fever, rash, arthralgia, or conjunctivitis.

Routine testing is not currently recommended for non-pregnant women or men with possible Zika virus exposure who do not have clinical illness, even if the couple is attempting conception. Testing in semen has not been validated and results might be difficult to interpret. It is not known whether a positive serologic test result in an asymptomatic man would indicate the presence of Zika virus in semen, or if a negative serologic test result would indicate the absence of Zika virus in semen.

Is testing of semen of men with possible exposure to Zika virus recommended?

No, testing of semen of men with possible exposure to Zika virus is not currently recommended. Testing of semen has not yet been validated and interpretation of the test results is not yet understood. Intermittent shedding in semen can occur with other viruses and the pattern of Zika virus shedding in semen is unknown. In addition, the detection of Zika virus RNA in semen might not indicate the presence of infectious virus in semen. Studies are under way to better understand the performance of these tests, the persistence of Zika virus in semen, and how best to interpret the results.

Who should health care providers contact to facilitate testing and interpretation of results?

For this information, health care providers should contact their state, local or territorial health department. For more information about testing.

When should testing be offered to pregnant women who have a history of sex without a condom with a male partner who traveled to or resided in an area of active Zika virus transmission?

Pregnant women who have had sex without a condom with a male partner with possible Zika virus exposure should be tested for Zika virus infection if:  she develops at least one sign or symptom of Zika virus disease;  her male partner had Zika virus disease or;  her male partner developed at least one sign or symptoms of Zika virus disease.

Zika and Pregnancy

What is known about the effects of Zika virus on pregnant women?

We expect that the course of Zika virus disease is similar to that in the general population.  No evidence exists to suggest that pregnant women are more susceptible or experience more severe disease during pregnancy. It is not known if pregnant women are more susceptible to Guillain-Barré syndrome.  Zika virus infection during pregnancy can cause microcephaly and other severe brain defects. It has also been linked with other adverse pregnancy and birth outcomes.

Is there any association between Zika virus infection and congenital microcephaly?

We know that Zika virus infection during pregnancy is a cause of microcephaly and other severe fetal brain abnormalities.

Studies are underway to investigate how Zika virus infection affects pregnancies, including the role of other factors (e.g., prior or concurrent infections, nutrition, and environment).

Is there any known association between maternal Zika virus infection and other adverse pregnancy outcomes?

Scientists are studying the full range of other potential health problems that Zika virus infection during pregnancy may cause. In addition to microcephaly, other problems have been detected among fetuses and infants infected with Zika virus before birth, such as defects of the eye, hearing loss, and impaired growth. Although Zika virus has been linked with these other problems in infants, there is more to learn. Researchers are collecting data to better understand how Zika virus affects mothers and their children.

What is the risk of adverse pregnancy or birth outcomes for women infected with Zika virus around the time of conception?

There is limited information available about the risk of periconceptional Zika virus infection. Three early case reports suggest there may be adverse outcomes associated with Zika virus infection in early pregnancy, including pregnancy loss and severe microcephaly. Information from other viral infections occurring around the time of conception indicate there are associations between periconceptional infections and adverse outcomes, although timing of infection and conception in these cases was often unknown.

How should pregnant patients who are considering travel to an area with active Zika virus transmission be counseled?

CDC recommends that pregnant women in any trimester not travel to an area with active Zika virus transmission. If a pregnant women is considering travel to one of these areas, she should talk to her health care provider. If she travels, she should be counseled to strictly follow steps to avoid mosquito bites during the trip. If a pregnant woman has a male partner who lives in or has traveled to an area with Zika, she should be counseled to either use condoms correctly and consistently or abstain from sex for the duration of her pregnancy.

How should pregnant women with male partners with Zika virus infection be counseled?

Given the potential risks of maternal Zika virus infection, for pregnant women whose male partners have or are at risk for Zika virus infection, using condoms consistently and correctly or abstaining from sex (vaginal intercourse, anal intercourse, and fellatio) for the duration of pregnancy is recommended. Recommendations will be updated as more information becomes available.

Should amniocentesis be considered for diagnosis of congenital Zika virus infection?

Consideration of amniocentesis should be based on the patient’s clinical circumstance. As for the evaluation of other congenital infections, amniocentesis may be considered in the evaluation of potential Zika virus infection. Healthcare providers should discuss the risks and benefits of amniocentesis with their patients.

Why has CDC changed its recommendation for amniocentesis?

Consideration of amniocentesis has been removed from the updated testing algorithms for the following reasons:

  • It is not known how sensitive or specific tests of amniotic fluid are for congenital Zika virus infection.
  • It is not known if a positive result is predictive of a subsequent fetal abnormality.  
  • If a positive result is predictive, it is not known what proportion of infants born after infection will have abnormalities.
  • The optimal time to perform amniocentesis to diagnose congenital Zika virus infection is not known.

If amniocentesis is considered in the evaluation for potential Zika virus infection, when should it be performed?

Amniocentesis is not recommended until after 15 weeks of gestation. Amniocentesis performed at ≥15 weeks of gestation is associated with lower rates of complications than when performed at earlier gestational ages (≤14 weeks of gestation). However, the exact timing of amniocentesis should be individualized according to the patient’s clinical circumstances. Referral to a maternal-fetal medicine specialist may be warranted. Health care providers should discuss the risks and benefits of amniocentesis with their patients.

How would the results of amniotic fluid testing for Zika virus inform clinical management of pregnant women?

A positive Zika virus RT-PCR result from amniotic fluid would be suggestive of intrauterine infection.  This information would be useful for pregnant women and their health care providers to assist in determining clinical management (e.g., antepartum testing, scheduling serial ultrasounds, delivery planning). A negative Zika virus RT-PCR result from amniotic fluid may prompt a work-up for other causes of microcephaly (e.g., other infections, genetic disorders).

Asymptomatic Pregnant Travelers

When should asymptomatic pregnant women with a history of travel be tested for Zika virus infection?

Testing can be offered from 2 to 12 weeks after pregnant women return from travel to areas with active Zika virus transmission. Information about serologic testing of asymptomatic persons is limited; on the basis of experience with other flaviriruses, we expect that antibodies to Zika virus will be present from 2 weeks after virus exposure and can persist for up to 12 weeks.

Pregnant Women Residing in Areas with Active Zika Virus Transmission of Zika Virus

Why is testing recommended for all pregnant women in areas with active Zika virus transmission?

Pregnant women who reside in areas with active Zika virus transmission are at risk of Zika virus infection throughout their pregnancy. Symptomatic pregnant residents should be tested for Zika virus infection. Asymptomatic pregnant residents may be offered screening with serologic testing at the initiation of prenatal care and mid second trimester. Local health officials should determine when to implement testing of asymptomatic pregnant women on the basis of information about levels of Zika virus transmission and laboratory capacity.

When should pregnant women living in areas with active Zika virus transmission be tested if they have symptoms consistent with Zika virus infection?

For pregnant women with at least one symptoms consistent with Zika virus disease, testing is recommended during the first week of illness.

When should pregnant women living in areas with active Zika virus transmission be tested if they do NOT have symptoms consistent with Zika virus infection?

For pregnant women who have no symptoms, IgM testing is recommended at the initiation of prenatal care with follow-up IgM testing mid-second trimester.

Does a prior negative Zika virus test result obviate repeat testing if new symptoms consistent with Zika virus develop later on?

N o. If new symptoms develop, a prior negative test for Zika virus does not rule out current infection. If new symptoms develop, a pregnant woman should be retested. During the first 7 days after symptom onset, viral RNA can often be identified in serum, and RT-PCR is the preferred test. However, viremia decreases over time, and a negative RT-PCR on serum collected 5-7 days after symptom onset does not exclude Zika virus infection. Serologic (IgM) testing should be performed.

Reproductive Age women in Areas with Active Zika Virus Transmission

How should women of reproductive age who reside in areas with active Zika virus transmission be counseled?

Particularly in the context of Zika virus transmission, it is important for women and their partners to plan their pregnancies. Health care providers should discuss reproductive life plans, including pregnancy intentions and timing with women of reproductive age. Decisions about pregnancy planning are personal. Decisions about attempting conception should be made in consultation with a health care provider.

Healthcare providers should ensure that women who want to delay or avoid pregnancy have access to safe and effective contraceptive methods that best meet their needs. Women and their partners who do not want to get pregnant now should use the most effective birth control correctly and consistently. Using condoms the right way, every time can reduce the risk of sexually transmitted diseases.

Long-acting reversible contraceptive methods, such as intrauterine devices and implants, are the most effective for preventing pregnancy. Further information is available at CDC’s Contraception and CDC’s Contraceptive Guidance for Health Care Providers webpages.

What is a reproductive life plan?

A reproductive life plan helps a woman think about her goals for having or not having children and how to achieve these goals. A woman’s plan depends on her personal goals and dreams. Reproductive life plan worksheets are available here.

How should women living in areas with active Zika virus transmission be counseled for preconception care in regards to Zika virus?

It is important for women and their partners to plan their pregnancies and discuss their reproductive life plans in the context of potential Zika virus exposure. As part of the planning process, women and their male partners should discuss with their healthcare providers the risks of local Zika virus transmission.  This discussion should include:

  • An assessment of the risk of Zika exposure, including the presence of mosquitoes in and around the home, protective measures practiced, and levels of local transmission of Zika.
  • Signs and symptoms of Zika.
  • Possible adverse outcomes of Zika infection during pregnancy.
  • Factors that might influence timing of pregnancy: fertility, age, reproductive history, medical history, and personal values and preferences.

Taking protective measures has been demonstrated to reduce the risk of vector-borne diseases, however, it might be impossible to eliminate the risk of Zika virus exposure during conception or pregnancy. The decision on timing of pregnancy is a personal decision and should be made by the individual or couple in consultation with their healthcare provider.

Women and Men with possible Zika virus exposure Who Desire Pregnancy

What is considered a “possible exposure” to Zika virus?

Possible exposure to Zika virus is defined as travel to or residence in an area with active Zika virus transmission or sex (vaginal, anal, or penis-to-mouth) without a condom with a man who traveled to or resided in an area with active transmission.

How should healthcare providers counsel men and women who have Zika virus disease who live in areas with active Zika virus transmission and who desire conception?

Healthcare providers for women and men residing in areas with active Zika virus transmission who have Zika virus disease should recommend they wait to attempt conception until the risk of viremia or viral shedding in semen is believed to be minimal.

How should healthcare providers counsel men and women who have been diagnosed with Zika virus disease who are trying to get pregnant?

For women and men who have been diagnosed with Zika virus or who have symptoms of Zika, like acute onset of fever, rash, joint pain or conjunctivitis after possible exposure to Zika virus, CDC recommends that health care providers advise:

  • Women to wait at least 8 weeks after their symptoms first appeared before trying to get pregnant.
  • Men to wait at least 6 months after their symptoms first appeared. Men should be counseled to also correctly and consistently use condoms for vaginal, anal, and oral (fellatio) sex or abstain during this time period if they are concerned about the possibility of transmitting Zika virus to their sex partners.

How should healthcare providers counsel women who do not live in an area with active transmission with possible Zika virus exposure but no clinical illness consistent with Zika virus disease?

For women who do not live in an area with active Zika transmission, but have possible Zika exposure, and do not experience symptoms, CDC recommends that healthcare providers advise waiting at least 8 weeks after their possible exposure before attempting conception.

How should healthcare providers counsel men who do not live in an area with active transmission, but have possible Zika virus exposure without symptoms and wish to attempt contraception?

For men without symptoms of Zika virus but who had possible exposure to Zika from who do not reside in an area with active Zika virus transmission, healthcare providers should recommend their patients wait 8 weeks after their possible exposure before trying to get pregnant. Men should correctly and consistently use condoms for vaginal, anal, and oral (fellatio) sex or abstain from sex during this time period if they are concerned about the possibility of transmitting Zika virus to their sex partners.

If symptoms do not develop, the couple could consider attempting conception or waiting longer. Given the limited data, healthcare providers should discuss with couples the many factors that might influence a decision about attempting conception, such as level of risk of Zika virus exposure and reproductive life plans.

How should health care providers counsel men and women who live in an area with Zika regarding attempting pregnancy?  

Men and women without symptoms of Zika virus but who have ongoing risk of Zika infection because they live in an area with Zika should talk with their healthcare providers about their pregnancy plans during a Zika virus outbreak and how they can prevent Zika virus infection during the pregnancy. Particularly in the context of Zika virus transmission, it is important for women and their partners to plan their pregnancies.

If either the man or woman have confirmed or presumed Zika virus disease:

  • Women should wait at least 8 weeks from symptom onset before attempting conception
  • Men should wait at least 6 months from symptom onset before attempting conception.
    • Men should also correctly and consistently use condoms for vaginal, anal, and oral (fellatio) sex or abstain from sex during this time period if they are concerned about the possibility of transmitting Zika virus to their sex partners.

How should healthcare providers counsel men and women with possible Zika virus exposure and clinical symptoms in the absence of a laboratory-confirmed test?

Persons who had possible Zika virus exposure and display one or more signs or symptoms consistent with Zika virus disease but did not have testing performed should follow recommendations for persons with Zika virus disease.

Can asymptomatic men transmit Zika virus to their partners?

It is not known if men without clinical illness consistent with Zika virus disease can transmit the virus sexually. There have been no reported cases of sexual transmission from asymptomatic men. Although viral shedding in semen in asymptomatic men with Zika infection has not been documented, it is biologically plausible.

What steps are recommended for persons with possible Zika virus exposure or Zika virus disease to wait to attempt conception?

Patients should be counseled about contraceptive methods, including the effectiveness of different contraceptive methods, and how to use these methods.

Condoms should be used if the male partner has had possible Zika virus exposure or Zika virus disease.

Why recommend waiting 6 months before attempting conception for men with Zika virus disease?

This time frame was recommended based on the limited information about how long Zika virus can stay in semen. It allows for three times the longest period of time that Zika virus RNA has been found in semen after symptoms first appeared. 

Why recommend 8 weeks before attempting conception for women with possible exposure but without clinical illness consistent with Zika virus disease?

This 8 week recommendation comes from the estimated upper limit of the incubation period for Zika virus disease, plus approximately triple the longest period of viremia in the published literature, plus extra time due to limited data and the potential for variability between people’s immune systems.

Why recommend 8 weeks before attempting conception for men with possible exposure but without clinical illness consistent with Zika virus disease?

It is not known whether men with asymptomatic Zika virus infection can transmit the virus sexually. There have been no reported cases of sexual transmission from asymptomatic men. Although it has not been documented, it is biologically plausible that men who have been infected with Zika virus but display no symptoms of Zika virus disease might shed Zika virus in the semen. In the absence of data and to be consistent with other recommendations, men who have possible Zika virus exposure without clinical illness consistent with Zika virus disease should wait at least 8 weeks after possible exposure before attempting conception. If symptoms do not develop, the couple could consider attempting conception or waiting longer. Given the limited data, health care providers should discuss with couples the many factors that might influence a decision about attempting conception, such as level of risk of Zika virus exposure and reproductive life plans.

Where can I find more information about preconception care?
Preconception care aims to promote the health of women of reproductive age before conception, to improve pregnancy-related outcomes. Preconception care for women who may be exposed to Zika virus should include a discussion of the risks of Zika infection to the mother and her fetus. Visit Preconception Care for more information.

Pregnant women living near the US-Mexico border

How should healthcare providers assess pregnant women who live on the U.S.-Mexico border? 

Healthcare providers who care for pregnant women who live along the US-Mexico border should assess their patients’ travel history, including frequency of travel across the US.Mexico border, and destinations. Areas of local transmission in regions of Mexico not bordering the US have been reported.  

For women who travel across the border regularly (e.g., daily, weekly), healthcare providers should follow CDC’s guidelines for pregnant women residing in areas with ongoing Zika virus transmission.

There are currently no reports of local transmission of Zika virus along the US-Mexico border. However, if local transmission occurs, local health officials should determine when to implement testing of asymptomatic pregnant women based on information about levels of Zika virus transmission and laboratory capacity.

Women trying to become pregnant through fertility treatment

How should women trying to become pregnant through fertility treatment be counseled?

There have been no reported cases of Zika virus transmission through assisted reproductive technology (ART). However, health care providers should follow the FDA’s guidance for tissue donation [PDF - 10 pages] in consideration of the Zika virus outbreak, including protocols for sperm donation. 

Has Zika virus been transmitted through donated gametes (egg, ova) or embryos?

No instances of Zika virus transmission during fertility treatment have been documented, but transmission through donated gametes or embryos is theoretically possible. Zika virus has been detected in semen, and sexual transmission has occurred.

The US Food and Drug Administration has issued guidance providing recommendations to reduce the potential transmission risk of Zika virus through donated tissues, including donated sperm, oocytes, and embryos from anonymous donors.

How should couples with possible Zika virus exposure who are planning to use their own gametes or embryos to conceive be counseled?

Fertility treatment for sexually intimate couples using their own gametes and embryos should follow the timing recommendations for couples attempting conception, although recommendations might need to be tailored to individual circumstances.

Future Pregnancy

How should providers counsel women with current or previous laboratory-confirmed Zika virus infection about future pregnancy?

Women of reproductive age with current or previous laboratory-confirmed Zika virus infection should be counseled that there is no evidence that prior Zika virus infection poses a risk of birth defects in future pregnancies. There is no evidence that a fetus conceived after maternal viremia has resolved would be at risk for fetal infection.

Women who have had Zika virus disease should wait at least 8 weeks after symptom onset to attempt conception. If their male partner also had confirmed or presumed Zika virus disease, he should wait at least 6 months after symptom onset to attempt conception. Men should also correctly and consistently use condoms for vaginal, anal, and oral (fellatio) sex or abstain from sex during this time period if they are concerned about the possibility of transmitting Zika virus to their sex partners.

Prenatal Diagnosis of Microcephaly

Why is fetal ultrasound recommended?

Fetal ultrasound is generally performed in pregnancies between 18-20 weeks of gestation to assess fetal anatomy as part of routine obstetrical care.  Although microcephaly and intracranial calcifications are typically detected during ultrasounds in the late second and early third trimester of pregnancy, these findings might be detected as early as 18-20 weeks gestation. Increasing evidence supports the link between Zika virus infection during pregnancy and adverse pregnancy and birth outcomes, including pregnancy loss, microcephaly, and brain and eye abnormalities. Hence, additional ultrasounds might provide an opportunity to identify findings consistent with congenital Zika virus infection and assist in determining clinical management.

Is ultrasound safe in pregnancy?

Ultrasound is performed during pregnancy when medical information is needed. It has been used during pregnancy for many years and has not been associated with adverse maternal, fetal, or neonatal outcomes. Ultrasound operators are trained to use the lowest power for the minimum duration of time to obtain the needed information. There is consensus among various national and international medical organizations (American College of Radiology, American College of Obstetricians and Gynecologists, and the Society of Maternal and Fetal Medicine) that ultrasound is safe for the fetus when used appropriately.

What prenatal ultrasound findings have been observed among infants with confirmed Zika virus infection?

Brain abnormalities reported in infants with laboratory-confirmed congenital Zika virus infection include microcephaly and disrupted brain development. Some infants with possible Zika virus infection have been found to have intracranial calcifications and eye abnormalities. It is not known if Zika virus infection caused any of these abnormalities.

Ultrasound findings that have been associated with Zika virus disease include microcephaly, intracranial calcifications, and brain and eye abnormalities. Studies are under way to learn more about the full spectrum of abnormalities (detected prenatally and postnatally) that might be associated with congenital Zika infection.

How is microcephaly diagnosed prenatally?

Microcephaly can be diagnosed during pregnancy with ultrasound. Microcephaly is most easily diagnosed by ultrasound late in the second trimester or early in the third trimester of pregnancy.

How early can microcephaly be diagnosed during pregnancy?

Microcephaly might be detected as early as 18-20 weeks of gestation however, detection by prenatal ultrasound can be challenging at this gestational age due to fetal position and fetal motion artifact. The optimal time to perform ultrasound screening for fetal microcephaly is not known. In the absence of microcephaly, the presence of intracranial calcifications before 22 weeks gestation might suggest a risk for the future development of microcephaly.

How accurately can ultrasound detect microcephaly in the context of a maternal Zika virus infection?

The accuracy of ultrasound to detect microcephaly in the setting of maternal Zika virus is not known and will depend on many factors such as the timing of maternal infection relative to the timing of screening, severity of microcephaly, patient factors (e.g., obesity), gestational age, equipment used, and the expertise of the person performing the ultrasound. Because the absence of congenital microcephaly and intracranial calcifications on ultrasound at one point in pregnancy does not exclude future microcephaly, additional ultrasounds may be considered at the discretion of the health care provider. CDC will update guidance for women and their health care providers as more information related to Zika virus infection and microcephaly becomes available.

If a prenatal ultrasound demonstrates microcephaly, how well does it predict microcephaly in the infant?

The sensitivity of prenatal ultrasound for detection of microcephaly depends on a range of factors (e.g., timing of screening, severity of microcephaly, patient factors). In a study of congenital microcephaly not caused by Zika virus infection, prenatally diagnosed microcephaly correlated with neonatal microcephaly approximately 57% of the time.

Can fetal MRI be used to detect microcephaly?

Fetal MRI is not a screening tool and should be used only to answer specific questions raised by ultrasound or used in occasional specific high-risk situations. Interpretation of fetal MRI requires specialized expertise and has limited availability in the United States.

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