The Centers for Disease Control and Prevention (CDC) has updated its interim guidance for health care professionals caring for pregnant women with possible Zika virus exposure.

According to the July 24 Morbidity and Mortality Weekly Report (MMWR), the dropping prevalence of Zika virus disease in the Americas since last year, plus new evidence indicating that Zika virus immunoglobulin M (IgM) antibodies can be detected far longer than previously thought, prompted the update.

The agency urged healthcare providers to consider these limitations when counseling pregnant women about the risks and benefits of testing for Zika virus infection during pregnancy. Key recommendations include:

• All pregnant women in the United States and U.S. territories should be asked at every prenatal care visit about possible Zika virus exposure before and during the current pregnancy.
• Pregnant women with recent possible Zika virus exposure and symptoms of Zika virus disease should be tested to determine the cause of their symptoms. The revised guidance calls for concurrent Zika virus nucleic acid test (NAT) and serologic testing as soon as possible through 12 weeks after symptom onset.
• Asymptomatic pregnant women with ongoing possible Zika virus exposure should be offered Zika virus NAT testing three times during pregnancy. The optimal timing and frequency of such testing is unknown.
• Asymptomatic pregnant women who have recent possible Zika virus exposure but no ongoing possible exposure are not routinely recommended to have Zika virus testing.
• Pregnant women with recent possible Zika virus exposure who have a fetus with prenatal ultrasound findings consistent with congenital Zika virus syndrome should receive Zika virus testing to help establish the etiology of the birth defects. Testing in this instance should include both NAT and IgM testing.

CDC resources on Zika, including more information about the updated guidelines, are available.