Zika-Linked Birth Defects More Extensive Than Previously Thought, Study Finds
A new study led by UCLA finds that abnormalities linked to Zika that occur in fetuses are more extensive and severe, than previously thought. According to the study, 46 percent of 125 pregnancies among Zika-infected women results in birth defects in newborns or ending in fetal death.
The study is published in the New England Journal of Medicine. It suggests that damage during fetal development from zika virus can occur throughout pregnancy and that other birth defects are more common than microcephaly, an instance where babies are born with very small heads.
According to Medical Express, Dr. Karin Nielsen, the study's senior author and a professor of clinical pediatrics in the division of pediatric infectious diseases at the David Geffen School of Medicine at UCLA and Mattel Children's Hospital said, the defects may only be detected weeks or even months after the baby is born,.
"This means that microcephaly is not the most common congenital defect from the Zika virus. The absence of that condition does not mean the baby will be free of birth defects," Nelson said.
She added that because there are other problems that do not manifest at birth and may not be evident until the baby attain the age of six months.
The results are a follow-up to a Brazilian study published in March, which used molecular testing to find the relation between Zika infection in pregnant women and a series of serious outcomes that included fetal deaths (miscarriages and stillbirths), abnormal fetal growth and damage to the central nervous system.
The UCLA study is the largest study that has been conducted of Zika-affected pregnancies. The women were closely monitored from the time they were infected with the virus to the end of their pregnancies. The women were enrolled before any abnormalities in their pregnancies had been identified, according to Science Daily.
The study was based on a larger number of 345 women from Rio de Janeiro, Brazil, enrolled in September 2015 through May 2016. Also, 182, or 53 percent of the women tested positive for Zika in the blood, urine or both.
Additionally, 42 percent of the women who did not have the Zika virus, were found to be infected with another mosquito-borne virus called chikungunya. Three percent of Zika-affected women also had chikungunya. The researchers also evaluated 125 Zika-affected women and 61 others who were not infected with the virus but who gave birth in July 2016.
The previous study was based mainly on prenatal ultrasound findings, in contrast with the current research that evaluated infants from Zika-affected pregnancies through physical examination and brain imaging.
There were nine fetal deaths among women with Zika virus during pregnancy. Five of those deaths occur in the first trimester.
Fetal deaths or birth abnormalities were present in 46 percent of infants from Zika-affected women, in contrast with 11.5 percent from women who tested negative.
The study finds that 42 percent of babies born to the Zika-positive mothers were found to have microcephaly, brain calcifications or brain lesions, lesions in the retina, feeding difficulties, deafness and several other complications.
The risks can occur at any stage of pregnancy as 55 percent of pregnancies were affected in the first trimester, 51 percent in the second trimester and 29 percent in the third trimester.
The researchers also stated that they examined the infants during their early stages when more subtle neurologic manifestations of the disease are not identified. They noted that follow-up examinations could probably turn up evidence of more neurologic diseases that could not be detected earlier.