CDC Updates Zika Guidance for Pregnancy, Prevention

Laurie Barclay, MD

July 25, 2016

Updated interim guidance from the Centers for Disease Control and Prevention (CDC) addresses testing and management of pregnant women with possible Zika virus exposure and prevention of Zika infection by sexual transmission, according to two reports published online July 25 in the Morbidity and Mortality Weekly Report.

"Zika virus continues to spread worldwide, and as of July 21, 2016, 50 countries and territories reported active Zika virus transmission," write Titilope Oduyebo, MD, from the Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, CDC, and colleagues in the first report. "Although most persons with Zika virus infection are asymptomatic or have mild clinical disease, infection during pregnancy can cause congenital microcephaly and other brain defects. Zika virus has also been linked to other adverse pregnancy outcomes, including miscarriage and stillbirth."

Highlighting the urgency of the new recommendations, Spain just reported the first European birth of an infant with microcephaly associated with Zika infection.

The CDC update reflects emerging data indicating that Zika virus RNA can be detected in blood and urine for prolonged periods (longer than the previously recommended 7-day window for testing after symptoms begin) in some pregnant women, and even in asymptomatic pregnant women.

To improve definitive diagnosis among pregnant women with Zika virus infection, the CDC therefore recommends extending the timeframe for real-time reverse transcription polymerase chain reaction (rRT-PCR) testing to 2 weeks and including rRT-PCR testing for some asymptomatic pregnant women.

All pregnant women in the United States and its territories should be evaluated for possible Zika virus exposure at each prenatal care visit, should avoid travel to an area with active Zika virus transmission, and should follow strict measures to prevent mosquito bites if they must travel to such areas. If their sex partner has traveled to or resides in an area with active Zika virus transmission, they should abstain from sex or use condoms or other barrier methods to prevent infection.

In addition to changes in testing recommendations, the update addresses clinical management of pregnant women with confirmed or possible Zika virus infection.

Regarding sexual transmission of Zika infection, the CDC has expanded its existing recommendations to cover all pregnant couples, including pregnant women with female sex partners, as well as couples who are not planning pregnancy.

These recommendations should be considered as interim guidance, to be updated when additional data become available.

Testing Recommendations for Zika Virus During Pregnancy

  • Symptomatic pregnant women with possible Zika virus exposure and clinical illness consistent with Zika virus disease (acute onset of fever, rash, arthralgia, conjunctivitis) should undergo the same testing, regardless of exposure type.

  • Possible exposures include travel to or residence in an area with active Zika virus transmission or unprotected sex with a partner who has traveled to or lives in such an area.

  • Symptomatic pregnant women seen less than 2 weeks after symptom onset should undergo Zika virus rRT-PCR testing of serum and urine.

  • Those seen 2 to 12 weeks after symptom onset should first undergo Zika virus and dengue virus immunoglobulin M antibody test, with follow-up serum and urine rRT-PCR testing for Zika if the Zika IgM antibody test result is positive or equivocal.

  • Symptomatic pregnant women with negative rRT-PCR results should receive both Zika virus IgM and dengue virus IgM antibody testing.

  • Asymptomatic pregnant women living in areas without active Zika virus transmission who are seen less than 2 weeks after their last possible exposure should undergo rRT-PCR testing, with a follow-up Zika virus IgM antibody test 2 to 12 weeks after exposure if rRT-PCR is negative.

  • Asymptomatic pregnant women not living in an area with active Zika virus transmission and first seen 2 to 12 weeks after last possible exposure should first undergo Zika virus IgM antibody testing, with serum and urine rRT-PCR if the IgM antibody test result is positive or equivocal.

  • Routine obstetric care for asymptomatic pregnant women with ongoing risk for Zika virus exposure should include Zika virus IgM antibody testing during the first and second trimesters, with immediate rRT-PCR testing when IgM antibody test results are positive or equivocal.

Recommendations for Clinical Management of Pregnant Women With Confirmed/Possible Zika Virus Infection

When laboratory results suggest recent Zika virus infection, consider serial ultrasounds every 3 to 4 weeks to evaluate fetal anatomy and growth, with individualized decisions regarding amniocentesis.

Microcephaly, intracranial calcifications, and brain and eye abnormalities are consistent with congenital Zika virus syndrome.

Considerations regarding amniocentesis include unknown sensitivity or specificity of amniotic fluid rRT-PCR testing for congenital Zika virus infection, whether a positive result predicts subsequent fetal abnormality, and what proportion of infants born after infection will have abnormalities.

For live births in women with recent laboratory-confirmed or presumptive Zika virus infection, evaluation should include:

  • cord blood and infant serum testing for Zika virus by rRT-PCR, and for Zika IgM and dengue virus IgM antibodies;

  • testing of cerebrospinal fluid if it is obtained for other reasons; and

  • Zika virus rRT-PCR and immunohistochemical (IHC) staining of umbilical cord and placenta.

For fetal losses in women with presumed recent Zika virus infection, CDC recommends Zika virus rRT-PCR and IHC staining of fetal tissues.

Manage women with recent dengue virus infection according to existing guidelines.

Pregnant women with no evidence of Zika virus or dengue virus infection should have prenatal ultrasound to identify fetal abnormalities consistent with congenital Zika virus syndrome.

If these are present, repeat Zika virus rRT-PCR and IgM testing to guide clinical management. If they are absent, the ongoing risk for Zika virus exposure should guide clinical management.

Recommendations for Prevention of Zika Virus Infection Through Sexual Transmission

"As of July 20, 2016, 15 cases of Zika virus infection transmitted by sexual contact had been reported in the United States," write John T. Brooks, MD, from the Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC, and colleagues in the second article. "Sexually transmitted Zika virus infection has also been reported in other countries."

In New York City, there was a recently reported case of female-to-male sexual transmission, and limited human and nonhuman primate data have shown detection of Zika virus RNA in vaginal secretions.

In addition to expanding recommendations to cover all pregnant couples, including pregnant women with female sex partners, the updated guidance also describes what couples who are not pregnant or planning to become pregnant can do to help prevent Zika virus transmission. The CDC has separately published its recommendations for couples planning to become pregnant.

Couples in which a woman is pregnant should consistently and correctly use barrier methods to prevent infection or abstain from sex (vaginal, anal or oral sex, or other activities that might expose a sex partner to genital secretions) for the duration of the pregnancy.

Barriers include male or female condoms for vaginal or anal sex and other barriers for oral sex.

Recommendations for couples who are not pregnant and not planning to become pregnant include the following:

  • Couples in which a partner had confirmed Zika virus or illness consistent with Zika infection should consider consistent, correct use of barrier methods or sexual abstinence for 6 or more months (infected men) or 8 or more weeks (infected women) after illness onset.

  • Couples in areas without active Zika transmission in which one partner traveled to or lives in an area with active Zika virus transmission but has remained asymptomatic should consider using barrier methods or abstinence for 8 or more weeks after that partner left the Zika-affected area.

  • Couples in areas with active Zika virus transmission might consider use of barrier methods or abstinence while active transmission persists.

Zika virus testing to evaluate risk for sexual transmission is currently of uncertain value, because of limited understanding of the duration and pattern of shedding of Zika virus in the male and female genitourinary tract.

Testing of specimens to determine risk for sexual transmission is therefore not recommended currently. However, Zika virus testing is recommended for persons who have had possible sexual exposure to Zika virus and who develop signs or symptoms consistent with Zika virus disease.

The authors have disclosed no relevant financial relationships.

Morb Mortal Wkly Rep. Published online July 25, 2016. Oduyebo full text, Brooks full text

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