What tests are used for diagnosing Zika virus infection?

From the Guidelines

Zika virus infection is typically diagnosed using a combination of nucleic acid amplification tests (NAATs), serologic evaluation for IgM antibodies, and plaque reduction neutralization tests (PRNTs).

Diagnostic Tests

• NAATs are the preferred method for diagnosing Zika virus infection, particularly in symptomatic patients and pregnant women with illness duration of 14 days or less 1.
• Serologic evaluation for IgM antibodies can identify additional infections, but results should be interpreted with caution due to cross-reactivity with other flaviviruses, such as dengue and West Nile virus 1.
• PRNTs are considered the reference standard for detection of neutralizing antibodies to arboviruses and should be performed to confirm positive IgM antibody test results, especially in pregnant women 1.

Testing Recommendations

• For symptomatic nonpregnant persons, NAATs should be performed on serum collected ≤7 days after symptom onset, followed by IgM antibody testing on NAAT-negative serum specimens or serum collected >7 days after onset of symptoms 1.
• For symptomatic pregnant women, concurrent NAATs and IgM antibody testing should be performed on serum and urine specimens collected as soon as possible within 12 weeks of symptom onset 1.

From the Research

Diagnostic Tests for Zika Virus Infection

The diagnosis of Zika virus infection can be challenging due to cross-reactivity with other flaviviruses. However, several tests have been developed to detect the virus. These include:

• Nucleic acid tests, such as reverse transcription-PCR (RT-PCR) assays, which detect viral RNA in blood, urine, and other bodily fluids 2, 3, 4, 5
• Serological tests, such as enzyme-linked immunosorbent assays (ELISAs), which detect Zika-specific antibodies in the blood 3, 4, 5, 6
• Plaque reduction neutralization test (PRNT) for confirmation of positive IgM results, particularly in pregnant women 5

Types of Samples Used for Testing

Various samples can be used for testing, including:

• Blood (whole blood, serum, plasma) 2, 3, 4, 5, 6
• Urine 2, 3, 4, 5, 6
• Saliva 5
• Cerebrospinal fluid (CSF) 5
• Semen 6

Challenges and Limitations

Despite the availability of these tests, there are still challenges and limitations to diagnosing Zika virus infection, including:

• Cross-reactivity with other flaviviruses, which can lead to false-positive or uninterpretable results 2, 3, 4, 6
• Limited utility of nucleic acid amplification testing due to the brief period of Zika shedding 3
• Need for accurate antibody tests to diagnose recent Zika infection 3