The Centers for Disease Control and Prevention (CDC) has issued interim guidance for the interpretation of Zika virus antibody test results. For persons with suspected Zika virus, a positive real-time reverse transcription-polymerase chain reaction (rRT-PCR) result confirms Zika virus infection, but a negative result does not exclude infection. In these cases, antibody testing can identify additional Zika virus infections. If immunoglobulin (Ig) M test results are positive, equivocal, or inconclusive, performing a plaque reduction neutralization test (PRNT) is needed to confirm the diagnosis. However, recent evidence suggests that a 4-fold higher titer by PRNT might not discriminate between anti-Zika virus antibodies and cross-reacting antibodies in all persons who have been previously infected with or vaccinated against a related flavivirus. Thus, a more conservative approach to interpreting PRNT results is now recommended to reduce the possibility of missing the diagnosis of either Zika or dengue virus infection. Other recommendations:

• All patients with clinically suspected dengue should receive appropriate management to reduce the risk for hemorrhagic medical complications.

• Pregnant women with laboratory evidence of a recent Zika virus infection or flavivirus infection should be evaluated and managed for possible adverse pregnancy outcomes and reported to the appropriate Zika virus pregnancy registry.

• Health care providers should consult with state or local public health authorities for assistance in interpreting test results.

Citation: Rabe IB, Staples JE, Villanueva J, et al. Interim guidance for interpretation of Zika virus antibody test results. [Published online ahead of print May 31, 2016]. MMWR Morb Mortal Wkly Rep. doi:http://dx.doi.org/10.15585/mmwr.mm6521e1.