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FAQs: Zika Serology Testing at the District of Columbia Department of Forensic Sciences Public Health Laboratory

Thursday, February 16, 2017

Background

The District of Columbia Department of Forensic Sciences Public Health Laboratory (DC-PHL) has been providing Zika virus testing for patients seen by DC health care providers since January 2016.

On December 14 2016, out of an abundance of caution, DC-PHL decided to take the Zika MAC-ELISA test offline after discovering some technical issues. After an extensive review, DC-PHL made the decision to retest all Zika serology specimens that were conducted at the DC PHL.

Only serum specimens collected between July 14 to December 14, 2016 are affected since any testing done prior were conducted directly by the Centers for Disease Control and Prevention (CDC).

The CDC will retest all pregnant female patients during the aforementioned timeframe. These specimens have already been sent and we have started to receive results. All other patient specimens have been sent to other public health laboratories that are approved to conduct this testing. We expect to have results for all retested specimens within three to four weeks.

The technical issues discovered by DC-PHL does not constitute any cause for alarm from the general public, and will not affect the District of Columbia Department of Health’s (DOH) management of probable or confirmed cases of Zika Virus Disease and infection.
DOH continues to manage probable and confirmed cases of Zika Virus Disease and infection using the most up-to-date recommendations from the CDC. DOH will proactively reach out to providers whose patients have been affected by a change in Zika virus test results to ensure the appropriate follow-up and reporting.

Frequently Asked Questions

What is the testing period that was affected?
Only specimens collected between July 14, 2016 and December 14, 2016 are affected, since serology testing done previously was conducted directly by the CDC. No further testing is required for previously reported rRT-PCR positive results.

How many samples are being retested?
409 specimens have been sent for retesting. 294 pregnant women samples were sent to CDC. The remaining 115 non-pregnant women and males were sent to other public health labs that are approved by the CDC.

Have you received any results?
We have received 62 results from the CDC. Sixty have come back negative; two have tested positive using the Zika, MAC-ELISA test. Those two specimens received further confirmatory testing and came back positive as an unspecified flavivirus. This means that the CDC detected a recent infection with a flavivirus but precludes identification of a specific infecting virus. For epidemiological purposes these results are treated as positive for Zika.

Where are the results posted and how will providers and patients be made aware of updated test results?
Results will be given to all providers that submitted specimens during the aforementioned time period. If we receive a different result than originally reported, DC-PHL will immediately call the provider and send an amended report. All results are shared with DOH. Providers are encouraged to reach out to their patients that have submitted specimens to let them know about any different results that were received. The DC PHL will not directly report results to patients.

When will the samples be retested and how soon will the updated results be revealed?
The CDC has agreed to retest all pregnant female patients during the aforementioned time frame. These specimens have already been sent and we have started to receive results. All other patient specimens have been sent to other public health laboratories (PHL) that are approved to conduct this testing. We expect to have results for all retested specimens within three to four weeks. If any results are found to be discordant from the original result obtained by the DC-PHL, someone from the DC-PHL will immediately contact the submitter via phone and an amended report will be faxed. If a Zika serology result is found to be positive, the CDC or PHL will conduct the required confirmatory test.

How long does the confirmatory testing take?
The confirmatory test can take up to three weeks to conduct.

Are there other options to get Zika testing?
Currently, there is one other FDA-approved test for Zika serological testing. This test is called the InBios ZIKV Detect IgM Capture ELISA test. This is the test that many of the commercial laboratories are currently utilizing. However, there was recently an FDA safety alert released on December 23, 2016 indicating that this test provides a higher than expected rate of false positive serology results that were not confirmed when sent to the CDC for confirmatory testing.

What will happen to patients who are now shown to be affected by Zika?

  • The District of Columbia Department of Health (DOH) will continue to follow the CDC’s "Updated Recommendations for Postnatal Management of Pregnant Women with Laboratory Evidence of Confirmed or Possible Zika Virus Infection."
  • If the patient is still pregnant, DOH will obtain information on progress during the pregnancy and increased frequency of ultrasounds will be recommended.
  • Testing recommendations around time of delivery and for the infant will remain the same, as noted within the CDC recommendations.
  • Affected infants will be followed up for one year. Follow-up includes assessment of developmental milestones at standard pediatrician visits and reporting to DOH.
  • If the infant has already been delivered, DOH will contact healthcare providers immediately to arrange for testing and start standard follow-up with chart review to obtain past information.

Will patients who were re-tested and found to be negative be followed?
Mothers and infants who have been retested as negative will not be actively followed up by DOH. However, DOH will ensure that healthcare providers know that if fetal anomalies or birth defects are noted, that a risk assessment for exposure for Zika in the parents should be completed. If any risks are found, the healthcare providers should immediately contact DOH at [email protected] or (202) 442-8141.

How will this change DOH’s management of Zika cases?
Management will not change from the CDC’s "Updated Recommendations for Postnatal Management of Pregnant Women with Laboratory Evidence of Confirmed or Possible Zika Virus Infection."