Puerto Rico had a Zika virus outbreak in 2016. While the Zika virus has been seen in humans since the 1950s, the 2016 outbreak was the largest that had been seen at that time. Showing similar symptoms to Dengue fever, a fairly common tropical disease, Zika was found to be different in its connection with birth defects.
Early concerns focused on microencephaly, a condition in which babies are born with abnormally small heads and brains. Other problems of the nervous system came up as scientists continued to study the virus.
Zika, which can be spread by mosquitoes or by sexual contact, was identified in 30 states in 2016, but Puerto Rico had the highest number of cases during the outbreak. A lack of funding and limited medical resources made it more difficult for Puerto Rico to control the disease.
A new report from the Centers for Disease Control follows up on babies from Puerto Rico and other U.S. territories whose mothers were believed to have been exposed to Zika during pregnancy. Lab evidence was used to identify the babies.The project, known as the U.S. Zika Pregnancy and Infant Registry (USZPIR), followed the infants from February 2017 to February 2018. Most were evaluated for various health issues.
6% of the babies were found to have at least one Zika-related birth defect. 9% had developmental abnormalities associated with Zika. 1% had both. Altogether, 1 in 7 of the children showed evidence of neurological abnormalities. These included hearing and vision loss, swallowing abnormalities, and brain development concerns, including microencephaly.
Since not all of the children received all the recommended evaluations, the researchers consider it possible that the actual numbers of children with abnormalities might be higher than reported. Children who died during the term of the study were excluded; some of these children might also have been affected. What’s more, the CDC expressed concern that data might have been lost in the wake of the 2017 hurricanes, either because infants did not have access to medical follow-up or because they left Puerto Rico and the Virgin Islands with their families. The 1 in 7 figure is therefore a conservative count.
This is the largest study so far of babies with prenatal exposure to the Zika virus. The researchers emphasize the importance of tracking the development of children whose mothers have been exposed to the Zika virus.
This year, there have been fewer than 100 cases of Zika virus reported in U.S. territories.
More information about the Zika virus.