Updated CDC Guidance on Zika in Pregnancy

Veronica Hackethal, MD

July 25, 2017

Updated interim guidance on caring for pregnant women with possible Zika virus exposure has been released by the Centers for Disease Control and Prevention (CDC).  The updated guidance is published online July 24 in Morbidity and Mortality Weekly Report.

"CDC has updated the interim guidance for U.S. health care providers caring for pregnant women with possible Zika virus exposure in response to 1) declining prevalence of Zika virus disease in the World Health Organization's Region of the Americas (Americas) and 2) emerging evidence indicating prolonged detection of Zika virus immunoglobulin M (IgM) antibodies," Titilope Oduyebo, MD, from the Zika Response Team, CDC, and colleagues write.

The updated guidance hinges on the difficulty of accurately interpreting Zika test results. Declining prevalence of Zika increases the likelihood for false-positive results, and new evidence shows that antibodies to Zika virus can be detected beyond 12 weeks after infection. So the presence of antibodies cannot reliably distinguish between Zika infection that happened before pregnancy and infection that happened during pregnancy. 

The definition of possible Zika virus exposure remains the same: travel to or living in an area where mosquitoes carry the virus or having sex with an individual who has traveled to or lives in such an area.

Key recommendations include the following:

  • Ask all pregnant women in the United States and US territories about possible Zika virus exposure before and during their current pregnancy at every prenatal visit. Providers should also ask about symptoms of Zika (eg, fever, rash, joint pain, conjunctivitis).

  • Pregnant women should not travel to areas at risk for Zika transmission. If their sexual partner lives in such an area, pregnant women should use condoms or abstain from sex during pregnancy.

  • Pregnant women with recent Zika virus exposure and symptoms of Zika should undergo Zika virus nucleic acid test (NAT) of serum and urine and IgM testing as soon as possible, through 12 weeks after symptom onset.

  • For pregnant women without symptoms but with ongoing possible exposure to Zika, IgM testing is no longer routinely recommended; offer Zika NAT testing three times during pregnancy, although optimal timing and frequency of NAT alone are unknown.

  • For asymptomatic pregnant women with recent possible Zika exposure, routine Zika testing is not recommended but can be considered using shared-decision making.

  • Pregnant women with recent possible Zika exposure whose fetus has ultrasound findings suggesting congenital Zika syndrome should undergo maternal testing with NAT and IgM.

  • For nonpregnant women with ongoing Zika exposure, Zika IgM testing is not warranted to establish baseline IgM levels as part of preconception counseling.

The guidance includes an updated comprehensive approach for testing placental and fetal tissues in certain cases, such as in a mother with laboratory-confirmed Zika whose fetus or infant has possible Zika-associated birth defects.

Algorithms for testing and interpreting results for symptomatic pregnant women with possible Zika exposure and asymptomatic pregnant women with possible Zika exposure are also provided.

The CDC recommends that providers counsel patients about the risks and benefits of Zika testing by using a shared decision-making model.

"This updated guidance emphasizes a shared decision-making model for testing and screening pregnant women, one in which patients and providers work together to make decisions about testing and care plans based on patient preferences and values, clinical judgment, and a balanced assessment of risks and expected outcomes," the authors emphasized.

The authors have disclosed no relevant financial relationships.

MMWR Morb Mortal Wkly Rep. Published online July 24, 2017. Full text

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