News from the FDA/CDC

FDA warns of false-positive results with Zika IgM test


A test used to detect Zika virus is producing a larger-than-expected number of false-positive results, according to a safety alert issued by the Food and Drug Administration.

The ZIKV Detect IgM Capture ELISA test is the first commercially available Zika serological IgM test – it was approved by the FDA in August 2016 and is used by several commercial laboratories. The test reports only presumptive positive results and a sample has to be sent to the Centers for Disease Control and Prevention for confirmation. Final results can take up to a month to be delivered. In most instances, the preliminary test results have matched the confirmed sample results.

Commercial testing facility Laboratory Corporation of America (LabCorp) has reported a greater-than-expected number of false-positive results from the ZIKV Detect test. The CDC has confirmed less than half of the presumptive positive results from ZIKV Detect tests sent by LabCorp.

The FDA recommends that health care providers inform patients that presumptive positive results need to be confirmed and that they not rely on positive IgM test results as the sole basis of patient management. If a patient is pregnant, the FDA recommends contacting the laboratory to expedite the confirmation testing.

FDA officials are working with LabCorp and ZIKV Detect manufacturer InBios International to determine if the false-positive results are related to problems with the test or the commercial testing facility.

Find the full safety alert on the FDA website.

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