Zika Virus Urine Testing Guideline
A couple of days after posting an update on testing for Zika Virus in last week's blog, CDC published a new interim guidance for Zika Virus testing of urine. The latest information is summarized in this week's blog.
Diagnostic testing for Zika virus infection can be accomplished using molecular and serologic methods. Real-time reverse transcription–polymerase chain reaction (rRT-PCR) is the preferred test for Zika virus infection because it can be performed rapidly and is highly specific. However, in most patients, Zika virus RNA is unlikely to be detected in serum after the first week of illness. Recent reports using adaptations of previously published methods suggest that Zika virus RNA can be detected in urine for at least 2 weeks after onset of symptoms.
A recent study by the Florida Department of Health Bureau of Public Health Laboratories compared reverse-transcription polymerase chain reaction (RT-PCR) test results for urine and serum specimens collected on the same days from 66 persons with Zika virus disease. Approximately twice as many urine specimens (61) tested positive than serum specimens (31). In specimens collected more than 5 days after symptom onset, 9 of 11 urine specimens tested positive but all serum specimens were negative. A further comparison of 53 persons with Zika virus disease with urine, saliva, and serum specimens collected on the same date found positive results from testing in 49 (92%) urine specimens, 43 (81%) saliva specimens, and 27 (51%) serum specimens.
Currently, the CDC Trioplex rRT-PCR assay is the only diagnostic tool authorized by the Food and Drug Administration for Zika virus testing of urine. Further investigation is needed to determine the sensitivity and utility of Zika virus rRT-PCR on urine specimens collected ≥14 days after onset of symptoms.
On the basis of the newly available data, CDC recommends that Zika virus rRT-PCR be performed on urine collected <14 days after onset of symptoms in patients with suspected Zika virus disease. Zika virus rRT-PCR testing of urine should be performed in conjunction with serum testing. A positive result in either specimen type provides evidence of Zika virus infection. Procedures for the collection and submission of body fluids, including urine specimens, have been described previously. CDC recommendations for Zika virus testing of serum and other clinical specimens remain unchanged at this time. CDC will continue to review and update guidance for Zika virus testing as new data become available.
Comparison of Test Results for Zika Virus RNA in Urine, Serum, and Saliva Specimens from Persons with Travel-Associated Zika Virus Disease — Florida, 2016, Morbidity and Mortality Weekly Report / May 13, 2016 / 65(18)
MMWR Morb Mortal Wkly Rep 2016;65:484. DOI: http://dx.doi.org/10.15585/mmwr.mm6518a10.
