DIAGNOSING AND TESTING ZIKA VIRUS
Diagnosing Zika Virus
Travelers to Areas with Active Zika Virus Transmission Who Are Not Pregnant
Most people infected with Zika virus are asymptomatic. Zika virus infection, when symptomatic, might include a constellation of symptoms and signs seen with other arboviral diseases, such as fever, maculopapular rash, arthralgias, and non-purulent conjunctivitis. Fever, by itself (or with other signs and symptoms, such as respiratory or gastrointestinal), might be enough to meet the minimal criteria that CDC and PA DOH require of patients to obtain approval for Zika virus testing. However, a patient with fever and respiratory or gastrointestinal symptoms suggests an alternative diagnosis, and Zika testing may not be worthwhile.
Patients that meet appropriate clinical and epidemiologic guidelines should be tested for Zika virus.
Travelers to Areas with Active Zika Virus Transmission Who Are Pregnant
It is recommended that pregnant women who have traveled to areas with active Zika virus transmission be tested for Zika virus regardless of whether they experienced symptoms related to Zika virus. Testing can be offered up to 12 weeks after pregnant women return from travel to areas with active Zika virus transmission.
Testing for Zika Virus
In the first week after the onset of symptoms, Zika virus disease may be diagnosed by performing real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) testing on serum. In addition to testing serum, rRT-PCR testing of urine should be performed within two weeks of onset of symptoms in patients.
After that, virus-specific IgM and neutralizing antibodies may develop that can be tested; however, cross-reaction with related flaviviruses is common and may be difficult to discern. In many cases, plaque-reduction neutralization testing (PRNT) can be performed to determine whether the flavivirus infection is caused by Zika virus.
Commercial PCR testing is available for persons who are symptomatic or became symptomatic within
the past two weeks. These specimens do NOT have to go through the Pennsylvania Department of Health Bureau of Laboratories, but an aliquot of serum should be saved. For antibody testing (two-12 weeks after exposure), or if PCR testing is desired through public health, requests should be made through the Bureau of Laboratories
. All testing will be completed in-house, at CDC or at another public health laboratory.
The Department of Health can also be consulted for assistance with interpreting laboratory results at 1-877-PA-HEALTH.
MEDICAL AND PUBLIC HEALTH LITERATURE
Other Key Peer-Reviewed Literature: