Zika causes further neurological defects
A multitude of additional neurological diseases are among the most recent birth defects discovered to be caused by the Zika virus, a disease once known mainly for causing microcephaly in newborns.
Microcephaly, which afflicts newborns by causing them to develop smaller brains and heads, was also found to be accompanied by gray and white matter volume loss, brainstem abnormalities and calcification. A recent study done by researchers from D’Or Institute for Research and Education in Rio de Janeiro, Brazil, published in RSNA Radiology, is one of the first of its kind to explore in-depth the various neurological birth defects caused by the Zika virus.
“Imaging is essential for identifying the presence and the severity of the structural changes induced by the infection, especially in the central nervous system,” said the study’s lead author Fernanda Tovar-Moll, M.D., Ph.D. “Microcephaly is just one of several radiological features,” Tovar-Moll said, describing the main method that the scientists used to pinpoint the Zika virus’ neurological effects.
The researchers began by viewing neurological images of patients with symptoms of the Zika virus, as well as retrospective imaging of autopsied individuals who had been afflicted with the virus in Northeastern Brazil, a region where the infection had been particularly severe.
It should be noted that 28 percent of all births occur in that region, adding to the desperation of the situation. Over 400 pregnant patients at the Instituto de Pesquisa in Campina Grande state Paraiba were analyzed between June 2015 and May 2016.
Doctors tested the patients for the Zika virus by using serologic analyses, or an analysis of their amniotic fluid, as well as reverse transcription polymerase chain reaction, a method used in molecular biology that is used to find RNA expression.
The virus is easily transmitted from mother to fetus by way of the fetal-placental barrier. Using imaging exams, such as fetal MRIs, postnatal brain CAT scans and longitudinal prenatal ultrasounds, the scientists found over 40 cases of fetuses that were either confirmed to have the Zika virus or presumed to have it.
“The first trimester is the time where infection seems to be riskiest for the pregnancy,” said the study’s co-author Deborah Levine, M.D., director of Obstetric & Gynecologic Ultrasound at Beth Israel Deaconess Medical Center and professor of radiology at Harvard Medical School. Levine continues, “From an imaging standpoint, the abnormalities in the brain are very severe when compared to other congenital infections.”
Indeed, 94 percent of fetuses with the Zika virus and 79 percent of fetuses presumed to have the virus were found to have abnormalities in their corpus callosum, a large bundle of nerve fibers that facilitate communication between the brain’s left and right halves. Additionally, many of the fetuses had ventriculomegaly, a brain disorder in which the ventricles are too large for the fluid they contain, resulting in developmental delays when the fetus is eventually born.
Ventriculomegaly, in conjunction with microcephaly, causes babies to be born with collapsed skulls, redundant skin folds and overlapping sutures.
The Zika virus is transmitted to humans by infected mosquitoes. However, around 80 percent of people who are infected with the disease are asymptomatic, making it difficult for the infected to know that they are carrying the disease. In the rare case that an infected person does show symptoms, they usually experience fever, rash, joint and muscle pain, headache and bloodshot eyes.
Pregnant women living in areas where mosquitoes are present have been encouraged by doctors to do as much as possible to prevent receiving mosquito bites. Covering up with clothing, using mosquito repellant and seeking testing are all encouraged.
As of July 2016, the Brazilian Ministry of Health has confirmed over 1,650 individual cases of microcephaly.