Laboratory Test for Zika virus Authorized for Emergency Use

Zika fever (Zika) is a disease caused by Zika virus that is spread to people primarily through the bite of an infected Aedes species mosquito. The most common symptoms of Zika are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting for several days to a week after being bitten by an infected mosquito.

In response to a request from the US Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA), the US Food and Drug Administration (FDA; Silver Springs, MD, USA) has issued an Emergency Use Authorization (EUA) for a diagnostic tool for Zika virus (ZIKV) that will be distributed to qualified laboratories and, in the USA, those that are certified to perform high-complexity tests.

The test, called the CDC Zika IgM Antibody Capture Enzyme-Linked Immunosorbent Assay (Zika MAC-ELISA), is intended for use in detecting antibodies that the body makes to fight a ZIKV infection. These antibodies, in this case, immunoglobulin M, or IgM, appear in the blood of a person infected with ZIKV beginning four to five days after the start of illness and last for about 12 weeks. The test is intended to be used on blood samples from people with a history of symptoms associated with Zika and/or people who have recently traveled to an area during a time of active Zika transmission.

As there are no commercially available diagnostic tests cleared or approved by the FDA for the detection of ZIKV infection, it was determined that a EUA is crucial to ensure timely access to a diagnostic tool. CDC's Zika MAC-ELISA is the first diagnostic test authorized for use in the USA for the detection of ZIKV during this situation in which there has been a determination that there is a significant potential for a public health emergency that has a significant potential to affect national security or the health and security of United States citizens living abroad and that involves ZIKV.

Results of Zika MAC-ELISA tests require careful interpretation. A positive test result indicates that a person was likely infected recently with the ZIKV. However, the test can give an incorrect positive. These false-positive results can occur when someone has been infected with another closely related virus (such as Dengue virus). When positive or inconclusive results occur, additional testing with the plaque reduction neutralization test to confirm the presence of antibodies to ZIKV will be performed by CDC or a CDC-authorized laboratory. CDC will begin distributing the test during the next two weeks to qualified laboratories in the Laboratory Response Network, an integrated network of domestic and international laboratories that can respond to public health emergencies.

Related Links:
US Centers for Disease Control and Prevention
US Food and Drug Administration