CDC updates guidance for clinical management of pregnant women infected with Zika

The CDC has issued interim guidance for health care providers who are treating pregnant women who have potentially been exposed to Zika.

The agency is stressing increased testing in both symptomatic and asymptomatic women.

"All pregnant women in the United States and U.S. territories should be assessed for possible Zika virus exposure at each prenatal care visit," Titilope Oduyebo, MD, and colleagues wrote in MMWR.

Testing for Zika

Pregnant women who present with or report symptoms such as rash, arthralgia, conjunctivitis or acute fever onset should be tested for Zika infection. The CDC recommends different testing based on how long after symptom onset the patient is being tested.

Symptomatic women being tested less than 2 weeks after onset or asymptomatic women who are not living in an area with active Zika being tested less than 2 weeks after positive exposure should have serum and urine tested by rRT-PCR. If those results are negative, symptomatic women should have dengue virus IgM antibody testing and Zika virus IgM testing. If either test is positive, plaque reduction neutralization testing (PRNT) should be done on the same sample in order to rule out false-positive results.

Symptomatic women being tested between 2 and 12 weeks after onset, asymptomatic women who are not living in an area with active Zika being tested between 2 and 12 weeks after exposure, and asymptomatic women living in an area with active Zika should receive Zika virus and dengue virus IgM antibody testing. If the dengue test is positive, PRNT should be performed. If the Zika virus test is positive or equivocal, patients should receive reflex Zika virus rRT-PCR serum and urine testing. If the rRt-PCR test is negative, PRNT should be performed.

Testing will determine whether there is no evidence of Zika, whether a patient has been recently infected with Zika, or whether there has been another infection.

As detailed by the CDC, Zika virus PRNT 10 and dengue virus PRNT < 10 indicates a recent Zika virus infection; Zika virus PRNT 10 and dengue virus PRNT 10 indicates a recent flavivirus infection; and Zika virus < 10 indicates no evidence of a recent Zika virus infection.

In addition, IgM antibody testing "might be considered" in both asymptomatic and symptomatic pregnant women who have sought care more than 12 weeks after possible exposure or symptom onset. Clinicians should perform rRT-PCR testing if they observe fetal abnormalities.

Oduyebo and colleagues noted that a negative IgM antibody test or rRT-PCR result in these patients does not rule out a Zika infection.

"Given the limitations of testing beyond 12 weeks after symptom onset or possible exposure, serial fetal ultrasounds should be considered," the authors wrote.

Prenatal, postnatal management

The CDC recommends performing ultrasounds every 3 to 4 weeks to evaluate fetal growth and anatomy in pregnant women with a recent Zika virus infection, when Zika virus infection is presumed and in cases when a specific virus cannot be identified.

"Ultrasound findings that have been associated with congenital Zika virus syndrome include microcephaly, intracranial calcifications, ventriculomegaly, arthrogyposis, and abnormalities of the corpus callosum, cerebrum, cerebellum, and eyes," Oduyebo and colleagues noted. "Consideration of amniocentesis should be individualized, because data about its usefulness in diagnosing congenital Zika virus infection are limited. The Zika virus RNA in the amniotic fluid might indicate fetal infection; however, a negative result does not exclude congenital Zika virus infection. In addition, persistent detection of Zika virus RNA in serum has been reported during pregnancy."

In cases of fetal losses, rRT-PCR and immunohistochemical staining of tissue is recommended.

In cases of live births, the agency recommends testing infant serum and cord blood using rRT-PCR as well as Zika IgM and dengue virus IgM antibodies. Cerebrospinal fluid can be tested if it has been collected for another reason. Zika virus rRT-PCR and immunohistochemical staining of the placenta and the umbilical cord are also recommended. – by Chelsea Frajerman Pardes

Disclosures: The researchers report no relevant financial disclosures.