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):
- Update: Interim Guidance for the Diagnosis, Evaluation, and Management of Infants with Possible Congenital Zika Virus Infection -- United States, October 2017 (Oct 20, 2017)
- Update: Interim Guidance for Health Care Providers Caring for Pregnant Women with Possible Zika Virus Exposure -- United States (Including U.S. Territories), July 2017 (July 24, 2017)
- Zika Virus Transmission -- Region of the Americas, May 15, 2015 - December 15, 2016 (Mar 31, 2017)
- Prevalence and Clinical Attributes of Congenital Microcephaly -- New York, 2013-2015 (Feb 10, 2017)
- Update: Interim Guidance for Preconception Counseling and Prevention of Sexual Transmisson of Zika Virus for Persons with Possible Zika Virus Exposure (Sept 30, 2016)
- Hearing Loss in Infants with Microcephaly and Evidence of Congenital Zika Virus Infection -- Brazil, November 2015 - May 2016 (Aug 30, 2016)
- Update: Interim Guidance for the Evaluation and Management of Infants with Possible Congenital Zika Virus Infection (Aug 19, 2016)
- Update: Interim Guidance for Health Care Providers Caring for Pregnant Women with Possible Zika Virus Exposure (July 25, 2016)
- Preventing Transmission of Zika Virus in Labor and Delivery Settings Through Implementation of Standard Precautions (Mar 22, 2016)