Interim Guidance for Interpretation of Zika Virus Antibody Test Results

Ingrid B. Rabe, MBChB; J. Erin Staples, MD, PhD; Julie Villanueva, PhD; Kimberly B. Hummel, PhD; Jeffrey A. Johnson, PhD; Laura Rose, MTS; Susan Hills, MBBS; Annemarie Wasley, ScD; Marc Fischer, MD; Ann M. Powers, PhD


Morbidity and Mortality Weekly Report. 2016;65(21) 

In This Article

Zika Virus Infection and Immune Response

Most Zika virus infections are asymptomatic.[12] Viremia is expected to occur from several days before illness onset until a week after illness onset.[6,13,14] Zika virus–specific IgM antibodies develop during the first week of illness.[5,6] Data on duration of IgM antibody persistence following Zika virus infection are limited. However, IgM antibodies against West Nile virus, a closely related flavivirus, have been detected in asymptomatic, infected blood donors for at least 3 months after their viremic donation, and almost half of tested patients with West Nile virus neuroinvasive disease had detectable serum IgM antibodies >1 year after illness onset.[15,16] Neutralizing antibodies to Zika virus develop shortly after IgM antibodies and consist primarily of IgG antibodies. Neutralizing antibodies are expected to persist for many years after flavivirus infections and are believed to confer prolonged, possibly lifelong, immunity.[17–19] In persons previously infected with a flavivirus or vaccinated against yellow fever, Japanese encephalitis, or tick-borne encephalitis, subsequent exposure to a related flavivirus can result in a rapid and brisk rise in neutralizing antibodies against multiple flaviviruses.[20] In addition, the neutralizing antibody titer against a flavivirus to which the person previously was exposed might be higher than the titer against the virus with which they were most recently infected.[20] For example, a person who was previously infected with dengue virus or who received yellow fever vaccine might respond with high levels of neutralizing antibodies against those viruses when later infected with Zika or West Nile viruses. When performing serologic testing, the presence of these neutralizing antibodies against multiple flaviviruses can preclude conclusive determination of which flavivirus was responsible for the recent infection.