August 28, 2017
On July 24, 2017, CDC released updated Interim Guidance for Healthcare Providers Caring for Pregnant Women with Possible Zika Virus Exposure. It includes changes in testing recommendations that are based, in part, on the decreasing incidence of infection in the Americas, the risk of false positive Zika virus test results, and the prolonged IgM response observed in some patients. This letter provides key highlights from the updated guidance.
- Travel Guidance for Pregnant Women
- Testing Recommendations for Pregnant Women and Test Results
- VDH Recommendations for Implementing Revised Guidance
- Pregnant women are still advised not to travel to areas with risk of Zika virus infection. Healthcare providers should continue to ask their patients about travel to or residence in any areas with risk of Zika virus infection or possible sexual exposure to someone with travel to or residence in those areas.
- In general, CDC emphasizes shared decision-making based on patient preferences, clinical judgment, and state/local public health recommendations.
- Pregnant women with possible exposure to areas with risk of Zika virus infection and signs or symptoms consistent with Zika virus disease (e.g., fever, rash, conjunctivitis, arthralgia, or fetal abnormalities on ultrasound that might be related to Zika infection) should be tested concurrently by Zika virus RNA nucleic acid test (NAT) and Zika virus IgM test. The testing window for NAT for pregnant women has been expanded to 12 weeks after onset, so concurrent NAT and IgM testing should be performed up to 12 weeks after onset.
- Asymptomatic pregnant women with ongoing possible exposure (i.e., lives in or frequently travels to an area with risk of Zika virus infection) should be offered Zika virus NAT testing three times during pregnancy. The first test should be performed upon initiation of prenatal care. Zika virus IgM testing is no longer routinely recommended for these asymptomatic pregnant women because of the prolonged IgM response that makes it difficult to differentiate an infection that occurred during the current pregnancy from one that occurred before the current pregnancy.
- For asymptomatic pregnant women with recent possible exposure, but without ongoing exposure, Zika virus testing is no longer routinely recommended because of the decline in the number of cases of Zika virus infection and the concerns for false positive test results. Testing should be considered on a case-by-case basis using a shared patient-provider decision-making model that takes into account patient preferences and clinical judgment. The Virginia Department of Health (VDH) recommends that clinicians consider the travel location and duration, the level of mosquito-borne transmission in the area of travel, and activities that might have impacted mosquito bite or possible sexual exposures (e.g., outdoor activities; wearing insect repellent and protective clothing; use of condoms).
- As the prevalence of Zika virus disease declines, the likelihood of false-positive test results increases. Before testing for Zika virus, healthcare providers should discuss the limitations of tests and potential risk of misinterpretations of test results, including false positives and false negatives. CDC materials for healthcare providers, including patient counseling scripts are available on the CDC website.
- For asymptomatic women who do not have ongoing possible exposure and where the infant or fetus does not have a Zika-related birth defect, placental or fetal tissue testing is not routinely recommended. Placental and fetal tissue may be tested for a fetus or infant with possible Zika virus-related birth defects when Zika virus infection has not been confirmed in the mother. Such testing must be arranged through your local health department.
- The revised testing recommendations for pregnant women will likely impact newborn infant testing because fewer pregnant women with laboratory evidence of Zika virus infection will be identified before the infant’s birth. Therefore, it is important for every infant born to a mother with possible Zika virus exposure to receive a comprehensive physical examination as defined in CDC revised interim guidance.
VDH Recommendations for Implementing the Revised CDC Guidance
Several commercial laboratories offer Zika virus testing, and providers are encouraged to utilize these options for all patients when clinically indicated and feasible. Virginia’s Division of Consolidated Laboratory Services (DCLS) will continue to offer public health testing for those patients who have been approved for testing by a local health department. For the purpose of public health testing in Virginia, VDH defines Zika virus infection risk areas as Category 1 or 2 according to the World Health Organization’s Zika Virus Country Classification. The exception is for travel confined to the United States, which would limit those with exposure to an area CDC has designated as a Zika cautionary area or area with active Zika transmission. The updated algorithm for patients eligible for public health testing and the laboratory testing instructions, developed in response to CDC’s revised recommendations summarized above, are available at these links:
- Patients Eligible for Public Health Testing if Private Lab Testing is Not Feasible Algorithm
- DCLS Laboratory Testing Instructions
As a reminder, contact your local health department to:
- Request public health testing
- Report all cases of suspected or confirmed Zika virus infection
Thank you again for your partnership during this evolving response to Zika and your continued care for your patients.
Marissa J. Levine, MD, MPH, FAAFP
State Health Commissioner