EXECUTIVE SUMMARY
A new CDC report indicates that of the 250 pregnant women in the United States who tested positive for Zika in 2016, about one in 10 delivered a fetus or baby with Zika-related birth defects.
- According to officials, confirmed infections in the first trimester posed the highest risk, with about 15% having Zika-related birth defects.
- Although the CDC recommends brain imaging after birth for all babies that are born to mothers who showed signs of Zika during pregnancy, just one in four babies with possible congenital Zika infection were reported to have received such testing after birth.
A new report from the CDC indicates that of the 250 U.S. pregnant women who tested positive for Zika in 2016, 24 delivered a fetus or baby with Zika-related birth defects.1
Although it has been more than a year since the CDC released the first travel alert related to Zika virus in the Americas, now is not the time to be complacent, according to CDC Acting Director Anne Schuchat, MD. Although Zika may seem like last year’s problem or an issue confined to Brazil and parts of the Caribbean, as of last count, more than 5,100 Zika virus cases have been reported in the continental United States and Hawaii, with the majority involving travelers returning from areas with active Zika transmission, she notes.
“While there is much left to learn about Zika, we do know this devastating outbreak is far from over, and the consequences of this outbreak are heartbreaking,” Schuchat said during a press briefing on the new report.
Zika testing is challenging because of its narrow timeframe for obtaining a positive laboratory result, and many infected people do not exhibit symptoms that would lead them to be screened.
With these challenges in sight, the CDC is monitoring all pregnant women with any evidence of recent Zika infection. Its surveillance shows that in 2016, about 1,000 pregnant women from 44 states who completed their pregnancies exhibited some evidence of a recent Zika infection and were at risk of delivering a fetus or baby with Zika-related birth defects. Further analysis indicates the majority of these women acquired the infection during travel to a Zika hot spot.1
Zika infection during pregnancy can cause serious damage to the brain and microcephaly in developing fetuses, and can lead to congenital Zika syndrome in babies. This syndrome includes a pattern of birth defects such as brain abnormalities, vision problems, hearing loss, and problems moving limbs. These babies may appear healthy at birth, but suffer from underlying brain defects or other Zika-related health problems.
“Some babies whose mothers were infected with Zika during pregnancy may be born with head size in the normal range, but might have underlying brain abnormalities, experience slowed head growth, and develop microcephaly after birth,” Schuchat said.
Examine Scope of Problem
The new report is an update on the proportion of fetuses or babies born with birth defects among pregnant women with possible Zika infection reported to the U.S. Zika Pregnancy Registry during 2016 in all 50 states and Washington, DC. Data are included from all states, the District of Columbia, and all U.S. territories except Puerto Rico, as those are monitored separately by the Zika Active Pregnancy Surveillance System.
A closer look at the data shows nearly 1,300 pregnant women with evidence of possible Zika infection were reported to the registry. Of the 1,000 pregnancies that were completed by the end of the year, more than 50 featured Zika-related birth defects. Among pregnant women with confirmed Zika infection, about one in 10 delivered a fetus or baby with birth defects.
Confirmed infections in the first trimester posed the highest risk, with about 15% containing Zika-related birth defects, according to the report. About one in three babies with possible congenital Zika infection had no report of Zika testing at birth.
Although the CDC recommends brain imaging after birth for all babies that are born to mothers with evidence of Zika during pregnancy, just one in four babies with possible congenital Zika infection were reported to have received brain imaging after birth.1
“Brain imaging, for example, a head ultrasound or a CT, is important to look for abnormalities, because we know that some babies have underlying brain defects that are otherwise not evident at birth,” Margaret Honein, PhD, the Zika Response’s Pregnancy and Birth Defects Task Force co-lead said in a briefing with reporters. “Because we do not have brain imaging reports for most of the infants whose mothers had Zika during pregnancy, our current data might significantly underestimate the impact of Zika.”
What Can You Do?
The CDC recommends that pregnant women avoid travel to areas with risk of Zika and avoid unprotected sex with a partner who has traveled to an area with Zika to prevent Zika-related birth defects in their babies, Honein said at the press briefing.
The agency continues working closely with health departments on the U.S. Zika Pregnancy Registry to follow up with infants regarding possible congenital Zika virus infection and better understand the full range of disabilities that can result from this infection, she stated.
Men with pregnant partners should use condoms or avoid having sex for the duration of the pregnancy if they have traveled to or live in an area with risk of Zika, according to Honein.
People who must travel to areas of active or suspected virus activity should understand the risks before they go and take extra precautions like using an Environmental Protection Agency-registered insect repellent to avoid mosquito bites. Pregnant women and their partners living in areas with risk of Zika should strictly follow steps to prevent mosquito bites and prevent sexual transmission by using condoms or not having sex during the pregnancy.
“We estimate that every year, about 40 million people in the United States travel to South America, Central America, or the Caribbean, where Zika has spread,” Schuchat said during the briefing. “And, unfortunately, every mosquito bite carries a risk.”
The CDC encourages all healthcare providers to educate families on Zika prevention, provide all needed tests and follow-up care, and support babies and families. The agency also continues updating guidance for healthcare providers on testing and clinical care for pregnant women and babies affected by Zika. It also is monitoring new infections and working to identify the long-term outcomes of congenital Zika infection.
Information for pregnant women, including fact sheets in several languages on protecting the pregnancy and mosquito prevention, is available at: http://bit.ly/2bMtot7. Specific information for healthcare providers, including evaluation and testing guidance, is available at: http://bit.ly/297HFxj.
The American College of Obstetricians and Gynecologists also offers many resources at: http://bit.ly/2py6EP1, including a Zika Toolkit, which has a patient video explaining the Zika virus.
Fortunately, work is underway to develop a useable vaccine as soon as possible, notes Robert Hatcher, MD, MPH, professor emeritus of gynecology and obstetrics at Emory University School of Medicine in Atlanta. In March 2017, the National Institute of Allergy and Infectious Diseases launched a Phase II clinical trial, which contains 2,490 healthy adult and adolescent subjects from areas of confirmed or potential active mosquito-transmitted Zika infection.
REFERENCE
- Reynolds MR, Jones AM, Petersen EE, et al. Vital signs: Update on Zika virus-associated birth defects and evaluation of all U.S. infants with congenital Zika virus exposure — U.S. Zika Pregnancy Registry, 2016. MMWR Morb Mortal Wkly Rep 2017;66:366-373.
Although it has been more than a year since the CDC released the first travel alert related to Zika virus in the Americas, experts warn now is not the time to be complacent.
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