CDC Updates Zika Testing Recommendations

The U.S. Centers for Disease Control and Prevention (CDC) issued a Health Alert Notice with updated guidance for testing women who live in or frequently travel to areas with a CDC Zika travel notice. The guidance includes an update on interpreting Zika virus Immunoglobulin M (IgM) serological tests and a recommendation for nucleic acid test (NAT) testing at least once per trimester.

The Problem
The CDC says its update reflects new data suggesting that Zika virus antibodies may stay in the body for months (beyond 12 weeks) in some infected individuals. Therefore, test results may not be able to determine how recently a person was infected.

The CDC's Recommendations
The CDC suggests that there may be a better, albeit still not conclusive, way to determine the timing of an infection. The following principles, the agency says, should be followed for testing pregnant women living in or frequently traveling to areas with Zika virus transmission or with a partner who tests positive for Zika virus infection:

• Test pregnant women promptly, using NAT, if they develop symptoms at any point during pregnancy or if their sexual partner tests positive for Zika virus infection;

• Consider Zika NAT testing at least once per trimester in asymptomatic women, in addition to IgM testing as previously recommended. The CDC warns, though, that a negative NAT test result does not rule out recent infection because viral ribonucleic acid (RNA) declines over time.

• NAT testing of amniocentesis specimens may provide additional information to help determine whether positive IgM test results suggest a recent infection.

• Consider IgM testing as part of pre-conception counseling to establish baseline IgM results before pregnancy.