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CDC updates Zika testing guidance following decline in disease prevalence
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The CDC recently updated its Zika testing guidance for pregnant women in the United States in response to a decline in disease prevalence and emerging evidence that indicates Zika virus immunoglobulin M antibodies may persist for months after infection.
According to Infectious Disease News Editorial Board member Lyle R. Petersen, MD, MPH, director of the CDC’s Division of Vector-Borne Infectious Diseases, and colleagues, the recent decline of Zika virus disease in the Americas increases the probability of false-positive test results.
“In addition, emerging epidemiologic and laboratory data indicate that, as is the case with other flaviviruses, Zika virus IgM antibodies can persist beyond 12 weeks after infection, they wrote in an MMWR. “Therefore, IgM test results cannot always reliably distinguish between an infection that occurred during the current pregnancy and one that occurred before the current pregnancy, particularly for women with possible Zika virus exposure before the current pregnancy.”
The CDC now recommends that health care providers:
- screen all pregnant women in the U.S. and its territories for possible Zika virus exposure before and during pregnancy and at every prenatal care visit;
- test pregnant women with possible exposure and symptoms of Zika virus disease with nucleic acid testing (NAT) and serologic testing as soon as possible;
- offer NAT testing to asymptomatic pregnant women with ongoing Zika virus exposure three times during their pregnancy;
- test pregnant women with recent exposure and who have a fetus with prenatal ultrasound findings that are consistent with congenital Zika virus syndrome with NAT and IgM tests; and
- test placental and fetal tissue specimens when appropriate, such as when a woman without laboratory-confirmed Zika virus infection has a fetus with possible birth defects associated with Zika virus infection.
The CDC does not recommend:
- Zika virus IgM testing as part of preconception counseling in nonpregnant women with ongoing exposure;
- routine screening for asymptomatic pregnant women who have recently been exposed to Zika virus through travel or sexual contact but do not have ongoing exposure; or
- routine testing of placental tissues among asymptomatic pregnant women with recent but not ongoing exposure and who have a liveborn infant without evidence of birth defects.
“In light of the updated recommendations that will likely reduce routine Zika virus testing of asymptomatic pregnant women with recent possible Zika virus exposure but without ongoing possible exposure, it is critical that pediatric health care providers inquire about possible maternal and congenital Zika virus exposure for every newborn,” Petersen and colleagues wrote.
They added that infants born to mothers with possible exposure during pregnancy but who were not tested should receive a comprehensive examination, including a standardized measurement of head circumference. Depending on the level of possible Zika exposure, health care providers should also consider whether an additional evaluation for congenital Zika virus infection is needed, including a head ultrasound and ophthalmologic assessment.
“CDC continues to evaluate all available evidence and will update recommendations as new information becomes available,” the researchers concluded. – by Stephanie Viguers
References:
CDC. Assessing Need for Testing. https://www.cdc.gov/zika/hc-providers/pregnant-women/testing-and-diagnosis.html. Accessed July 27, 2017.
Oduyebo T, et al. MMWR Morb Mortal Wkly Rep. 2017;.doi:10.15585/mmwr.mm6629e1.
Disclosure: The researchers report no relevant financial disclosures.