Zika Virus: Information for Providers
Zika virus is spread through the bite of an infected Aedes mosquito. It can also be passed from a pregnant person to their baby and spread through sex. Most people who get infected do not get sick. Those who do get sick usually experience mild symptoms, including fever, rash, joint pain, and conjunctivitis.
For the latest guidance surrounding Zika, including on prevention and on caring for pregnant women and infants, review New York State's Zika Virus Information for Health Care Providers. Routine Zika virus testing is not currently recommended for most people with the exception of symptomatic pregnant women who had recent travel, or had sex with someone who lives in or recently traveled, to areas with active dengue transmission and a risk of Zika.
Evaluation and Testing
Zika virus testing is only recommended for pregnant people who have Zika symptoms and were recently in an area with current or past Zika transmission, or had sex with someone who was. Zika and dengue viruses have a similar global distribution and clinical presentation, and are both flaviviruses, which can lead to cross reactions in serologic immunoassays. Therefore, patients with suspected Zika infection should also be evaluated for possible dengue.
Zika virus testing is available at commercial laboratories. Positive specimens should be forwarded to New York State Wadsworth Center for confirmation.
How to Interpret Tests
Zika IgM antibodies may persist for over a year after infection, similar to other flavivirus infections. Serologic cross reactivity with dengue virus can also produce a positive Zika IgM result. Determining the timing of infection relative to pregnancy may be complicated for women with prior or ongoing exposure. Providers should acknowledge and convey to patients the limitations of Zika serology for clinical decision-making.
A positive Zika IgM antibody test result for a pregnant person could mean:
- Zika virus infection during current pregnancy, indicating the pregnancy is likely at risk from Zika.
- Zika virus infection before current pregnancy, indicating the pregnancy is not likely at risk from Zika.
- False positive result, indicating the pregnancy is not likely at risk.
Guidance for Interpretation of Discordant IgM Results Between PHL and Commercial Laboratories (PDF)