Diagnostic tests for Zika virus
| Population | Test | When used | Limitations |
|---|---|---|---|
| Healthy adults or children | Zika virus immunoglobulin M (IgM) in serum | 2–12 weeks of illness | Possible cross-reactivity with other flaviviruses Limited availability |
| Real-time polymerase chain reaction (RT-PCR) in serum | First week of illness | May be negative by day 4 of illness Limited availability | |
| Plaque reduction neutralization assay | Confirmatory testing for patients with positive IgM | Limited availability Labor-intensive | |
| Pregnant women | Fetal ultrasonography | Pregnant women with a positive Zika virus test Pregnant women exposed to Zika virus who present after 12 weeks of exposure | Needs to be repeated every 3–4 weeks during pregnancy Availability may be limited |
| RT-PCR of amniotic fluid | Microcephaly or intracranial calcifications present on ultrasonography | Significance of results has not been conclusive | |
| Newborns suspected of being infected | Histopathology of umbilical cord and placenta | Fetal loss, Zika virus suspected Newborn with microcephaly and intracranial calcifications | Presumptive diagnosis Limited availability |
| RT-PCR of cord serum, frozen tissue (cord, placenta) | Fetal loss, Zika virus suspected Newborn with microcephaly and intracranial calcifications | Presumptive diagnosis Limited availability |