How should asymptomatic pregnant women with a history of travel to an area with active Zika virus transmission be tested for Zika virus infection?
The type of testing recommended varies depending on the time of evaluation relative to symptom onset.
Asymptomatic pregnant women living in areas without active Zika transmission who are evaluated up to 2 weeks after possible exposure should receive RNA NAT (nucleic acid testing) on whole blood, serum, and urine. A positive RNA NAT result confirms the diagnosis of recent maternal Zika virus infection.
Asymptomatic pregnant women with a negative RNA NAT test result require additional testing to exclude infection, because the presence of viral RNA in whole blood, serum, and urine depends on several factors.
These women should return 2–12 weeks after possible Zika virus exposure for Zika virus IgM antibody testing. A positive or equivocal IgM result should be confirmed by plaque reduction neutralization testing (PRNT).
Asymptomatic pregnant women living in an area without active Zika virus transmission who seek care 2-12 weeks after possible exposure to Zika virus, should be offered Zika virus IgM antibody testing.
Emerging laboratory data indicate that some pregnant women can have evidence of Zika virus in their blood, even if they are asymptomatic.
If the Zika virus IgM result is positive or equivocal, an immediate RNA NAT test is indicated to provide a definitive diagnosis. If the RNA NAT result is negative, PRNT should be performed.
