First isolated in 1947 the Zika virus was known to occur within a narrow equatorial belt from Africa to Asia, but last year it became an epidemic after it’s eastward spread in South America during 2015-2016 outbreak. The virus is still making headlines as it emerged from the western parts of United States as well.
First it was suspected that this Zika virus during pregnancy can cause a birth defect of the brain called microcephaly and other severe fetal brain defects. Other problems have been detected among fetuses and infants infected with Zika virus before birth, such as defects of the eye, hearing deficits, and impaired growth. There have also been increased reports of Guillain-Barré syndrome, an uncommon sickness of the nervous system, in areas affected by Zika.
In a recent study done by researchers at D’Or Institute for Research and Education (IDOR), it’s been found that microcephaly, a very usual feature in cases of Zika virus gestational infection, is just one of several observed brain changes.
The research, published in the scientific journal Radiology, assessed pregnant women, fetuses and newborns infected by zika virus through computed tomography, magnetic resonance imaging and ultrasound. According to Dr. Fernanda Tovar-Moll, correspondent author of the study and researcher at IDOR and UFRJ, the study was essential to identify the severity of the neurological changes induced by the viral infection in the developing central nervous system. Dr. Deborah Levine, coauthor of the study, also stresses the importance of describing different malformations in the brains of fetuses and newborn babies caused by zika virus.
Unlike observed in other infections such as toxoplasmosis, rubella, cytomegalovirus and herpes, the fetuses’ and babies’ brains infected by zika virus showed cortical malformations and changes located at the junction of the brain’s white and grey matter. The researchers also identified reduction in brain volume, cortical development abnormalities and ventriculomegaly, a condition in which the brain cavities (spaces filled with fluids) are larger than normal. Notwithstanding the fact that almost all babies have shown abnormalities in head circumference, cases of normal circumference in babies with severe ventriculomegaly were also found.
The results also pointed out abnormalities in the corpus callosum, a bundle of nerve fibers that allows communication between the brain’s left and right sides and further in neuronal migration, i.e., the neurons didn’t move to its correct destination in the brain.
According to Dr. Fernanda Tovar-Moll from the research team they are now working on a follow up study to investigate how the congenital infection by zika virus can interfere not only in the prenatal period but also in the postnatal brain maturation. “Microcephaly is only the tip of the iceberg” says Dr. Fernanda.
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