“The Zika story is not over, and we have so much more to learn.”
The largest study to date on long-term outcomes of infants exposed to Zika virus before birth has found evidence of health problems that have been associated with the virus in 14 percent of those who were at least one year old for whom information was available. At least 6 percent had Zika-related birth defects, a rate 30 times higher than seen in infants not exposed to the virus, and 9 percent had neurological problems that have been associated with the virus, including difficulties swallowing, movement disorders, hearing loss, vision deficits, and signs of developmental delay. While Zika has been confirmed to cause microcephaly — abnormally small head size — as well as an eye defect evident at birth, longer term follow up so far has been insufficient to prove that Zika causes the other problems noted, or to determine the extent of potential problems, Peggy Honein, director of the U.S. Centers for Disease Control and Prevention said.
Ongoing monitoring babies exposed to Zika before birth, whether they appear to have Zika-linked disorders or not, is critical to appropriate care, and to learning more about impacts of the virus, Honein said.
“This is providing us with the first clues of how common these might be,” she said.
The findings are based on data gathered from among more than 4,000 pregnancies with laboratory evidence of Zika infection in U.S. territories, including Puerto Rico, the U.S. Virgin Islands, Guam, Samoa and the freely associated states of Micronesia, the Marshall Islands and Palau. By February of this year, 2100 of those infants had turned a year old, and information from follow-up health checks was available on 1,450. Many of those children did not appear to have been affected by Zika at birth, and monitoring for potentially Zika-related impacts was incomplete, Honein said. Only half had been examined for hearing problems and only a third for vision problems.
While microcephaly is linked to exposure to the virus earlier in pregnancies, Zika-related impacts can occur during any trimester, Honein said. The CDC continues to recommend that women at any stage of pregnancy not travel to areas where local transmission is ongoing, but recently updated recommendations for couples planning pregnancies — now saying that men with possible exposure should wait three months before trying to conceive. The CDC previously recommended waiting six months.
The last local transmission of the virus reported in the U.S. within the 50 states and Washington, DC, occurred in Texas and Florida, in 2017, Dr. Lyle Peterson of the CDC said. The CDC plans to analyze information from 2500 pregnancies with Zika-exposure within the 50 states and Washington, DC.
The latest findings were released today in the CDC’s Vital Signs report.
“The Zika story is not over,” Honein said. “We have so much more to learn.”