Testing

Which Patients Should be Tested for Zika?

What Testing Routes are Available?

Many commercial laboratories, including Quest and LabCorp have been authorized to perform Zika virus testing. We encourage providers to use commercial laboratories for testing in non-complicated situations, such as:

  • A patient (including a pregnant woman) who is asymptomatic or has uncomplicated clinical illness and Zika virus exposure related to travel to an area with Zika.

The public health lab should still be used for testing in complex situations, such as:

  • A fetus or infant with microcephaly or signs of congenital Zika virus syndrome whose mother was exposed to Zika virus,
  • A person with Guillain-Barré syndrome and exposure to Zika virus, OR
  • When sexual, local mosquito-borne, laboratory exposure, or blood transfusion/organ transplant exposure is suspected is suspected

If in doubt about the appropriate testing route to use, physicians should contact the Alameda County Acute Communicable Disease Unit and/or submit a Testing Request Form, available on our Specimen Submission page.

What Tests are Available / Appropriate for Different Patients?

Currently, there are three tests available for use when Zika virus infection is suspected:

  • Molecular Test for Zika Virus: Zika virus RNA can sometimes be detected early in the course of illness.
  • Serologic Test for Zika Virus: Zika virus-specific IgM and neutralizing antibodies typically develop toward the end of the first week of illness and last for a few months.
  • Plaque Reduction Neutralization Test (PRNT): Samples with presumptive positive, equivocal, or inconclusive IgM test results must be forwarded for confirmation by PRNT.

Which test to use is dependent upon a person’s exposure and symptom history. For more information on Zika virus tests, see CDPH’s 8/2/17 Updated Guidance for Health Care Providers Caring for Pregnant Women with Possible Zika Virus Exposure.

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