Zika birth defects found in 1 in 10 infected United States pregnant women

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One in 10 pregnant women with confirmed Zika virus infections had an infant or fetus who showed signs of birth defects, according to a new report from the Centers of Disease Control and Prevention. The information comes from state officials reporting to the U.S. Zika Pregnancy Registry from January 15 to December 27, 2016, in the 50 states, Washington, D.C., and all U.S. territories except Puerto Rico. "With warm weather, a new mosquito season and summer travel rapidly approaching, prevention is crucial to protect the health of mothers and babies". All health-care providers, especially obstetricians and pediatricians, need to improve monitoring of these infants.

A total of 1,297 pregnant women with some evidence of Zika infection were reported to the U.S. Zika Pregnancy Registry in 2016.

Of the 972 women who went on to give birth, 51, or 5 percent, delivered children stricken with Zika-associated birth defects.

While microcephaly, or having a smaller-than-normal head, has become the symbol of Zika's impact on newborns, researchers have since documented a still incomplete laundry list of problems the virus is capable of causing - from hidden brain damage to frozen-in-place joints and blindness. It also can lead to congenital Zika syndrome, which is a pattern of birth defects that includes brain abnormalities, vision problems, hearing loss, and limb defects. These women had tested positive for either the Zika virus or an "unspecified flavivirus", which could include Zika or another virus in that family, such as the dengue virus. The risk was even higher among women infected in the first trimester of pregnancy, where 15 percent of pregnancies resulted in a fetus or baby with birth defects. Schuchat, however, said the recommendation for physical exam and tests for Zika-affected babies is relatively new, and many clinicians might not be aware of it and may not know the value of brain scanning.

"Zika virus is causing a lot of anxiety among my patients and their partners, who are accustomed to traveling for work or to visit family", says Siobhan Dolan, MD, MPH, an obstetrician-gynecologist at Montefiore Medical Center in the Bronx and medical advisor to the March of Dimes. She said the CDC is still receiving about 30 to 40 reports of pregnant women infected with Zika virus each week. Imaging could help detect brain abnormalities not visible at birth, and the CDC now recommends neuroimaging for any infant whose mother has Zika. That is because researchers may not have been aware of all the asymptomatic Zika cases: Some women without symptoms may not have gotten tested for Zika, and consequently, their cases would not be reported.

Note that this surveillance data from the CDC suggests that roughly 10% of Zika-infected babies in the United States have a Zika-associated abnormality. Most had traveled to an area where the virus was known to be transmitted by mosquitoes and were exposed to the virus in that way.

"It's important to look for abnormalities", said Dr. Peggy Honein, chief of the birth defects branch at the CDC.

The CDC's registry data included all 50 states, Washington, D.C. and territories except Puerto Rico.

Last year, a backlog of Zika test results led to hundreds of patients, a lot of them pregnant women, waiting months to receive their results. Because of limitations of testing, only tests done within the first few weeks of Zika can test specifically for the Zika virus.

Zika infection during pregnancy also has been linked to miscarriage and stillbirth. CDC experts published their findings today in a Vital Signs report in Morbidity and Mortality Weekly Report (MMWR).

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