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Zika Resources for Health Care Providers

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 group of related signs and symptoms 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.

Pregnant Women who Travel to Areas with Active Zika Virus Transmission 

For pregnant women who have traveled to areas with active Zika virus transmission and experience symptoms related to Zika virus, testing can be offered up to 12 weeks after returning from travel to areas with active Zika virus transmission, or 12 weeks from the onset of symptoms. Testing of asymptomatic women is not recommended unless the travel is ongoing on a daily or weekly basis.

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 differentiate. 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 becamesymptomatic within the past two weeks. These specimens do NOT have to go through the Pennsylvania Department of Health Bureau of Laboratories, but a portion of the serum sample should be saved. For antibody testing (two to twelve 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

CDC Guidance (MMWR Reports):