FDA Issues Warning To Doctors: Don't Rely Heavily On IgM Test For Zika Diagnosis and Treatment

January 11, 2017

FDA Issues Warning To Doctors: Don't Rely Heavily On IgM Test For Zika Diagnosis and Treatment

The U.S. Food and Drug Administration released a statement that warned healthcare providers not to completely trust the results attained from commercial IgM Assay for a Zika diagnosis.

The problem is the high number of false positives the test has resulted in.

Healthcare providers use the ZIKV Detect IgM Capture ELISA test as a preliminary Zika virus detection test. The Centers for Disease Control and Prevention had recommended this test to be used on patients who had signs of Zika or give it to those who traveled to countries where the Zika virus is prominent.

The FDA said Laboratory Corporation of America reported the false positives, but that additional investigation is needed to find out why it's happening. The FDA said using IgM tests to determine if a person has the Zika virus is still useful, but doctors need to use other tests before determining a treatment plan.

The test was developed for the sole purpose of a preliminary diagnosis, which means confirmatory tests are still necessary. A confirmation of a Zika diagnosis can take between one week and one month to attain. The FDA said since the ZIKV Detect test can result in a false positive, it's important doctors wait for the confirmation results before decisions are made on the treatment.

The FDA said LabCorp began using the ZIKV Detect test and found it had a higher than anticipated false positive results, with half of those results being actually positive for the Zika virus.

While confirmation tests can take nearly a month to get results, the samples that come from pregnant women will be tested first. People who test positive with the ZIKV Detect test will be told that they may or may not have the Zika virus and not to make any decisions based on that information.

The FDA, CDC, LabCorp and ZIKV Detect test manufacturer InBios are trying to figure out why the test is giving false positives. The CDC, in an effort to combat the Zika virus, has given $184 million to states, universities, local jurisdictions and territories to Zika preventive measures. The funding is the results of the 2016 Zika Response and Preparedness Appropriates Act, which gave the CDC $350 million.

The $184 million is being distributed in this manner:

$25M to protect areas most at risk for local Zika transmissions

$97M to local, state, city and territorial health departments

$40M to four universities to fund vector-borne disease centers

$14M to the development of Puerto Rico's Vector Control Unit

$8M to the research of microcephaly and congenital disabilities

A group of researchers in Brazil has asked government officials to reassess the legal consequences of those seeking an abortion. According to their letter, 56 percent of women have avoided getting pregnant because of the virus. Brazil has had nearly 110,000 locally-acquired cases of the Zika infection since the outbreak was first noted. On top of that, since 2015, more than 2,200 fetuses and infants were determined to have the congenital Zika virus syndrome.

While the Zika virus isn't considered a worldwide threat any longer, it's still a big problem for pregnant women and their growing fetuses. With further research, doctors will learn what the complications Zika has on congenital infection, which makes the constant observation, diagnostic and deterrence efforts so important.