Clinical Testing and Diagnosis for Zika Virus Disease

Doctor looking into a microscope

Nucleic acid amplification test, or NAAT, is a generic term referring to all molecular tests used to detect viral genomic material. NAAT assays are the preferred method of diagnosis because they can provide confirmed evidence of infection. Despite the specificity of molecular testing, false positive NAAT results have been reported.

Because of the short period and low level of Zika virus RNA in serum, a negative NAAT does not exclude recent Zika infection. For this reason, Zika virus immunoglobulin (Ig) M antibody testing is recommended in certain situations. IgM generally is detectable starting in the first week after onset of symptoms and persists months to years. IgM testing is complicated by cross-reactive antibodies to other flaviviruses, which might make conclusive determination of which flavivirus is responsible for the person's recent infection difficult. False-positive results are more common with IgM than NAAT and can occur due to non-specific reactivity or cross-reactivity with other flaviviruses.

Plaque reduction neutralization tests (PRNT) measure virus-specific neutralizing antibody titers. PRNTs may resolve false-positive IgM antibody results caused by non-specific reactivity and help identify the infecting virus. However, due to cross-reactivity, PRNT might not discriminate between flaviviruses antibodies, especially following secondary flavivirus infections.

For infant diagnosis, PRNT cannot distinguish between gestational parent and infant antibodies in specimens collected from infants at or near birth. Based on what is known about other congenital infections, gestational parent antibodies are expected to become undetectable by 18 months of age and might become undetectable earlier.

Resource‎

Below is a summary of CDC's Zika testing guidance. It will be updated as needed to address the epidemiology of Zika virus. Healthcare providers are encouraged to contact their local, state or territorial health departments for guidance on Zika testing and submitting specimens in their respective states.

Asymptomatic pregnant patient

Lived in or traveled to the United States and its territories during pregnancy Traveled to an area with an active CDC Zika Travel Health Notice during pregnancy

Traveled to an area with current or past Zika virus transmission outside the US and its territories during pregnancy

Symptomatic pregnant patient

Lived in or traveled to an area with an active CDC Zika Travel Health Notice during pregnancy OR had sex during pregnancy with someone living in or with recent travel to an area with an active CDC Zika Travel Health Notice


Lived in or traveled to an area with current or past Zika virus transmission during pregnancy

Had sex during pregnancy with someone living in or with recent travel to an area with current or past Zika virus transmission



Interim Guidance for Health Care Providers Caring for Pregnant Women with Possible Zika Virus Exposure — United States (Including U.S. Territories), July 2017‎

Read more about CDC's shared decision-making model for testing and screening pregnant women for Zika virus infection.

Pregnant patient having a fetus with prenatal ultrasound findings consistent with congenital Zika virus infection

Lived in or traveled during pregnancy to an area with an active CDC Zika Travel Health Notice or current or past Zika virus transmission
OR had sex during pregnancy with someone living in or with recent travel to an area with an active CDC Zika Travel Health Notice or current or past Zika virus transmission

Keep Reading: Collecting & Submitting Placental and Fetal Tissue Specimens for Zika Virus Testing

Symptomatic non-pregnant patient

Living in or with recent travel to the United States and its territories