Which lab testing for Zika virus infection is indicated in congenital Zika virus infection?

Updated: Jun 30, 2021
  • Author: Bhagyashri D Navalkele, MD, MBBS; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Molecular and serological diagnostic testing for Zika virus is recommended for confirmation of diagnosis. Other than Zika virus RNA testing in infant's serum and urine and IgM antibodies in serum, cerebrospinal fluid testing for NAAT and IgM antibody testing is recommended to increase diagnostic yield. 

Cord blood testing is not recommended due to false-positive and false-negative test results. 

Following clinical and diagnostic algorithm should be followed as recommended by CDC:

Recommendations for the evaluation of infants with possible congenital Zika virus infection based on infant clinical findings, maternal testing results, and infant testing results - United States, October 2017. Courtesy of the Centers for Disease Control and Prevention (CDC).

Recommendations for the evaluation of infants with Recommendations for the evaluation of infants with possible congenital Zika virus infection based on infant clinical findings, maternal testing results, and infant testing results - United States, October 2017. Courtesy of the Centers for Disease Control and Prevention (CDC).

CDC has provided guidance on interpretation of NAAT and IgM antibody testing for diagnosis of congenital Zika virus infection. 

Interpretation of results of laboratory testing of infant’s blood, urine, and/or cerebrospinal fluid for evidence of congenital Zika virus infection. Courtesy of the Centers for Disease Control and Prevention (CDC).

Interpretation of results of laboratory testing of Interpretation of results of laboratory testing of infant’s blood, urine, and/or cerebrospinal fluid for evidence of congenital Zika virus infection. Courtesy of the Centers for Disease Control and Prevention (CDC).

Differentiation between dengue and Zika virus infection in infants can be performed by PRNT, if IgM test on infant's initial sample is nonnegative (nonnegative serology terminology varies by assay and might include “positive,” “equivocal,” “presumptive positive,” or “possible positive”) and NAAT is negative. PRNT does not distinguish between infant or maternal passive antibodies collected from infant during or immediately after birth. As maternal antibodies are usually not detected past 18 months, diagnostic testing past 18 months can help to diagnose congenital Zika virus infection.

In infants with nonnegative IgM and positive Zika neutralizing antibodies at birth, PRNT at age of ≥ 18 months can confirm or rule out congenital Zika virus infection: 

  • A positive PRNT is suggestive of presumed congenital Zika virus infection. It is difficult to interpret timing of infection in infants traveling or residing in areas with Zika. 
  • A negative PRNT is suggestive of absence of congenital Zika virus infection. 

Infants with clinical findings consistent with congenital Zika syndrome and maternal laboratory evidence of possible ZIKV infection during pregnancy, PRNT at age of ≥ 18 months can be considered if infant testing was negative (NAAT and IgM antibody) or not performed at birth.


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