Mistakes at U.S. lab force hundreds of Zika tests to be repeated
17/02/2017 11:46AM

        Officials in Washington, D.C.'s
        public health laboratory had to repeat Zika tests for nearly
        300 pregnant women, including two women who were mistakenly told
        they tested negative for the mosquito-borne virus that has been
        shown to cause birth defects.
        A routine check of lab practices in December revealed that
        all of the lab's Zika tests were coming back negative, raising
        concerns about their accuracy, a spokeswoman for the Centers for
        Disease Control and Prevention said on Thursday.
        CDC experts, who have been working with the lab since
        mid-January, discovered that technicians doing Zika testing were
        skipping a step, causing all of the test results to be negative,
        said Dr. Wendi Kuhnert-Tallman, who co-leads the CDC's Zika lab
        task force.
        The faulty tests were performed between July 14 and Dec. 14
        of 2016, the lab said in a statement on its website.
        A total of 409 specimens were sent for re-testing, including
        samples from 294 pregnant women. CDC is re-testing all 294 of
        the samples from pregnant women, and the remaining 115 tests
        from men and non-pregnant women were sent to other CDC-approved
        public health labs.
        So far, the D.C. lab said it has received 62 test results
        from pregnant women back from the CDC. Of these, 60 tested
        negative and two tested positive. Confirmatory tests were only
        able to determine that the women had been recently infected with
        a flavivirus, a family of viruses that includes Zika, dengue and
        "What that means is that we did see evidence of past
        infection, but we can't say for sure it's Zika," Kuhnert-Tallman
        Zika has been shown to cause a range of birth defects when
        pregnant women are infected, including vision and hearing
        problems, developmental delays and microcephaly or small head
        size, a sign that the brain had not developed properly.
        Kuhnert-Tallman said CDC has completed about 100 more tests,
        and results are being sent back to the lab and the doctors who
        ordered them. Another 129 are still pending.
        "We anticipate those will be finalized within two to three
        weeks," Kuhnert-Tallman said.
        The District of Columbia Department of Forensic Sciences
        Public Health Laboratory has ceased Zika testing and will not
        resume until it demonstrates to the CDC that it is performing
        the tests correctly, Kuhnert-Tallman said.