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Lack of Zika-Specific Test Creates Dilemma for Some Pregnant Women

Washington - Pregnant women who’ve traveled to Latin America and the Caribbean are advised to be tested for the Zika virus afterward. But medical researchers have discovered there’s a problem with that advice: Some diagnostic tests will return positive results even when a person hasn’t contracted Zika.

That ambiguity can force pregnant women who fear giving birth to babies with severe brain damage to make life-changing decisions based on incomplete information.

The discovery by Zika researchers that current antibody tests don’t distinguish between Zika and dengue, another mosquito-borne virus, is the latest twist in the scientific world’s confrontation with a virus long thought relatively harmless but now thought able to cause serious birth defects as well as life-threatening complications in adults.


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US Health Officials Brace for Zika Battle - May 9, 2016

. . . There currently are two approved lab tests for Zika, according to the CDC:

    One is the PCR test, which tests for Zika by looking for the virus' genetic material in a person's bloodstream.

    The other test, called the MAC-ELISA, examines a person's blood for Zika antibodies. These antibodies show that a person has been infected with Zika and has developed the antibodies to fight off the virus. . . .

. . . However, the PCR test has one major drawback -- it can only detect an active Zika infection, and people usually clear the virus from their bloodstream within a week, Pesano said. . . .

. . . Pregnant women who are worried they've been infected with Zika will need the MAC-ELISA test, which can show whether they have ever had the virus. But even that test has drawbacks, Hellerstedt noted. It's tougher to administer, slower to produce results, and not as accurate as might be hoped, he said.

A woman who's been infected with another virus in the same "family" as Zika -- dengue or chikungunya, for example -- would receive a positive result from the MAC-ELISA, Hellerstedt said. Blood with any positive result would then need to be forwarded to the CDC for even more rigorous testing before a woman would know whether her pregnancy truly is at risk.


CLICK HERE - CDC - Zika Virus - Diagnostic Testing

CLICK HERE - CDC - Zika Virus - State & Local Public Health Laboratories

CLICK HERE - FDA - Zika Virus Emergency Use Authorization - Reporting by Natalie Grover in Bengaluru; Editing by Ted Kerr - May 10, 2016

The U.S. Centers for Disease Control and Prevention updated its diagnostic testing guidelines for the Zika virus on Tuesday, based on early data showing that it can be found at higher levels or last longer in urine than in blood.

The agency now recommends that its preferred diagnostic test, called Zika virus RT-PCR, be conducted on urine collected less than 14 days after the individual suspected of having the disease starts experiencing symptoms.

The test should be performed in conjunction with blood testing if the specimens are collected less than seven days after the onset of symptoms, the CDC said.

A positive result in either case provides adequate evidence of infection, the agency said.


CLICK HERE - MMWR - Interim Guidance for Zika Virus Testing of Urine — United States, 2016

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