The Food and Drug Administration (FDA) recently gave emergency-use approval to a laboratory test, the Trioplex real time RT-PCR assay, developed by the Centers for Disease Control and Prevention (CDC). The test can check blood samples for the presence of Zika, dengue and chikungunya viruses. When done in conjunction with blood samples, it can also be used to detect Zika virus in urine, spinal fluid or amniotic fluid.
Chikungunya, dengue and Zika viruses are all transmitted by mosquitos and have similar signs and symptoms, such as fever, rash, joint pain, and conjunctivitis (pink eye). However, chikungunya and dengue have not been linked to the same health consequences as Zika virus.
Though most adults (80%) with Zika have no noticeable symptoms and others may only have mild symptoms, the virus can cause microcephaly, or small brains, in babies born to women infected by the virus. Zika has also been linked to Guillain-Barré syndrome, a rare condition that can cause temporary paralysis.
Previously, tests for the three viruses would have to be done separately. The Trioplex real time RT-PCR assay detects the genetic material (RNA) of the three different viruses and distinguishes between them.
With emergency-use authorization, the new Trioplex real time RT-PCR test is available to public health laboratories for use now, instead of having to go through a lengthy approval process. Zika was deemed as having significant potential to cause a public health crisis, justifying the emergency-use authorization by the FDA.
Only certain public health laboratories will be able to provide the test after verifying that they can successfully perform the assay. Those labs are part of the Laboratory Response Network, which responds to public health emergencies. Though the test will not be available in hospitals or clinics, healthcare practitioners will be able to order it through their state and local public health departments. Results can take from four days to two weeks, according to the CDC.
The Trioplex real time RT-PCR assay is for the detection of the viral nucleic acid within the first week of illness when symptoms appear. A different test called the MAC IgM ELISA may be used as an alternative test for those patients who may have been infected but the length of time has passed when the Trioplex real time RT-PCR can be performed. The MAC IgM ELISA detects antibodies in the blood that develop in response to a Zika infection. It was also developed by the CDC and was given emergency-use authorization by the FDA in February.
These new tests are important developments in the fight against Zika, which has been circulating mainly in South and Central America and the Caribbean. Late last year, the CDC issued a travel alert for more than 20 countries because of the outbreak of Zika virus. (See CDC Warns Travelers, Especially Pregnant Women, About Zika Virus.)
Over 300 cases have been diagnosed in U.S. states, though so far only in people who have returned from traveling to areas where mosquitos are actively spreading the disease and in people infected by someone who traveled to those regions. For the latest list of affected areas, visit the CDC webpage on Areas with Zika.
The CDC continues to monitor Zika and regularly updates its information on Zika for the public.