Three out of every 1,000 babies born in 15 U.S. states and territories, in 2016, had a birth defect possibly associated with Zika virus infection in the mother.
Three out of every 1,000 babies born in 15 states, including Massachusetts, in 2016 had a birth defect possibly linked to the Zika virus infection in the mother, according to the Centers for Disease Control and Prevention.
The virus is spread by infected mosquitoes as well as through unprotected sex.
The report, "Population-Based Surveillance of Birth Defects Potentially Related to Zika Virus Infection -- 15 States and U.S. Territories, 2016," also said that areas with local transmission of Zika - southern Florida, a portion of south Texas, and Puerto Rico - saw a 21 percent increase in births with outcomes most strongly linked to Zika virus in the last half of 2016 compared with births in the first half of that year.
According to a CDC statement released Jan. 25, the report reviewed nearly one million births in the 15 states and territories in 2016, including Florida (select southern counties), Georgia (select metro-Atlanta counties), Hawaii, Iowa, Illinois, Massachusetts, New Jersey, New York (excluding New York City), North Carolina (select regions), Puerto Rico, Rhode Island, South Carolina, Texas (select regions), Utah, and Vermont.
Zika virus can be transmitted through the placenta leading to complications of pregnancy and birth defects.
A total of of 2,962 infants and fetuses met the criteria for having birth defects potentially related to Zika virus infection. They were summarized as follows:
- About half (49 percent) were born with brain abnormalities and/or microcephaly (small head size)
- 2 in 10 (20 percent) had neural tube defects and other early brain abnormalities
- 1 in 10 (9 percent) had eye abnormalities without brain abnormalities
- More than 2 in 10 (22 percent) had nervous system damage, including joint problems and deafness, without brain or eye abnormalities
CDC researchers are said to anticipate that there could be another increase in possible Zika-related birth defects when 2017 data are analyzed because many pregnant women exposed to Zika virus in late 2016 gave birth in 2017.
The Massachusetts Department of Public Health has issued clinical guidance and testing recommendations for infants born to mothers with possible Zika virus exposure and infants with congenital Zika virus syndrome.
According to the department, data from the U.S. and its territories indicates that five to six percent of pregnancies associated with maternal Zika virus infection result in a possible Zika related birth defect.
Massachusetts had about 100 confirmed cases of travel exposure to Zika between January 2016 and June 2017, with the highest number of cases - about 28 - in the month of June 2016, according to state health department.
The CDC release said the current report underscores the "importance of surveillance for birth defects potentially related to Zika virus infection and the need for continued monitoring in areas at risk for Zika."
According to the CDC, the number of pregnant women with any laboratory evidence of possible Zika virus infection, between 2015 and 2018, in the United States and District of Columbia is 2,395, though many pregnant women with possible exposure were likely never tested.
According to the World Health Organization, the rise in the spread of Zika virus has been accompanied by a rise in cases of microcephaly - a condition where a baby is born with an unusually small head - and Guillain-Barre syndrome. In this syndrome, a person's immune system attacks the peripheral nerves.
An outbreak of the virus in Brazil in 2014 quickly spread.