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Analysis shows birth defects in 10% of US pregnancies affected by Zika
Around 10% of pregnancies in women with confirmed Zika virus infection in the United States last year resulted in a fetus or baby with birth defects, the CDC announced today.
The proportion was even higher — approximately 15% — in women infected during the first trimester, according to the first comprehensive analysis of the U.S. Zika Pregnancy Registry.
However, despite primarily mosquito-borne virus’ association with brain abnormalities, most infants born to potentially infected mothers did not receive appropriate postnatal neuroimaging after they were born, according to researchers.
“Zika continues to be a threat to pregnant women across the U.S.,” CDC Acting Director Anne Schuchat, MD, said in a statement. “With warm weather and a new mosquito season approaching, prevention is crucial to protect the health of mothers and babies. Health care providers can play a key role in prevention efforts.”
Researchers analyzed data from 1,297 pregnancies in 44 states that were reported to the USZPR between Jan. 15 — the day the CDC announced a Zika travel warning for pregnant women — and Dec. 27 last year. Their findings were published in MMWR.
According to the analysis, only 25% of the 895 infants born to mothers with possible recent Zika infection received postnatal neuroimaging, and just 65% tested at least once for the virus. The researchers said every infant born from pregnancies with possible recent exposure to Zika should receive postnatal imaging and testing for Zika to ensure proper care.
“Although microcephaly was the first recognized birth defect reported in association with congenital Zika virus infection, Zika virus-associated brain abnormalities can occur without microcephaly, and neuroimaging is needed to detect these abnormalities,” the researchers wrote.
The CDC established the USZPR last year to monitor all women with evidence of recent Zika infection. The registry was created as suspicions rose that the Zika outbreak centered in Brazil was to blame for a spike in cases of microcephaly.
Experts now know that Zika, once considered a benign virus, can cause a whole suite of illnesses called congenital Zika syndrome The virus can cause not just microcephaly, but brain damage, seizures, vision and hearing problems, difficulty swallowing and joints with limited range of motion.
The researchers analyzed all completed pregnancies in the U.S. with laboratory evidence of possible recent Zika virus infection reported to the USZPR. The analysis included live births and pregnancy losses at any gestational age.
According to the findings, Zika-associated birth defects were reported in approximately 5% of the 972 fetuses or infants from completed pregnancies that had laboratory evidence of possible recent Zika infection. The proportion rose to approximately 10% among 250 completed pregnancies in which Zika infections were confirmed in a laboratory.
“These findings underscore the serious risk for birth defects posed by Zika virus infection during pregnancy and highlight why pregnant women should avoid Zika virus exposure and that all pregnant women should be screened for possible Zika virus exposure at every prenatal visit, with testing of pregnant women and infants in accordance with current guidance,” the researchers wrote.
Although locally acquired Zika cases have been reported in the U.S. in Florida and Texas, most of the women from the cases reported to the USZPR had traveled to an area where the virus was circulating. (The registry includes all cases reported in the U.S. and U.S. territories, excluding Puerto Rico, which is covered by a separate surveillance system.)
Zika is primarily spread through the bite of an infected Aedes aegypti mosquito but also can be sexually transmitted by both women and men. The CDC recently updated its travel guidance to recommend that pregnant women avoid any areas where there is a risk for Zika infection, including places where the virus has not been documented but is likely to be circulating. The agency also recommends that women avoid unprotected sex with a partner who has traveled to an active Zika area. – by Gerard Gallagher
Reference:
CDC. Zika screening tool for pregnant women. 2017. https://www.cdc.gov/zika/pdfs/zikapreg_screeningtool.pdf. Accessed April 4, 2017.
Reynolds MR, et al. MMWR Morb Mortal Wkly Rep. 2017;doi:10.15585/mmwr.mm6613e1.
Disclosures: The researchers report no relevant financial disclosures.