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 CHICAGO (Reuters) - Researchers on Wednesday reported new evidence strengthening the association between Zika virus and a spike in birth defects, citing the presence of the virus in the brain of an aborted fetus of a European woman who became pregnant while living in Brazil. An autopsy of the fetus showed microcephaly or small head size, as well as severe brain injury and high levels of the Zika virus in fetal brain tissues, exceeding levels of the virus typically found in blood samples, researchers in Slovenia from the University Medical Center in Ljubljana reported in the New England Journal of Medicine. Brazil has confirmed more than 400 of those cases as microcephaly, and identified the presence of Zika in 17 babies, but a link has yet to be proven. In early 2015, a Zika outbreak was identified in northern Brazil, where other viruses spread by mosquitoes (like dengue) were circulating. There’s no specific treatment and no vaccine for Zika, which was considered an extremely mild infection before Brazil called the alarm last year. In the NEJM paper, the mother showed signs of Zika infection during her 13th week of pregnancy, but ultrasounds during her 14th and 20th week were normal. At 32 weeks, an ultrasound showed that the fetus was abnormally small — in the third percentile for fetal weight — and its head was below the second percentile for circumference. The woman chose to get an abortion, and doctors performed an autopsy, where they found viral replication of Zika in the fetus's brain. Ultrasounds at 14 weeks and 20 weeks were normal. The fetus was negative for 13 other viruses that may cause fetal abnormalities; the woman had no history of genetic abnormalities in her family. Other viruses known to damage the brains of developing babies, such as West Nile virus, cytomegalovirus and rubella, can also affect the eyes. But microcephaly can be caused by a number of viruses, including rubella and toxoplasmosis, as well as by malnutrition or maternal alcoholism. Damage from the virus may have halted brain development at 20 weeks, though it's not clear how the virus was infecting nerve cells. In January, a team of researchers at the U.S. Centers for Disease Control and Prevention reported that they, too, found evidence of Zika virus in brain samples from Brazil taken from two miscarriages and two newborns who died shortly after birth.
– The Zika virus' apparent effect on fetuses is on shocking display in a new study in the New England Journal of Medicine that was rushed to publication given the virus' spread. Though it offers no definitive link between Zika and fetal abnormalities, the study does produce the first evidence of virus transmission from mother to child and "the strongest evidence yet that the virus causes abnormally small heads and incomplete brain development," reports the Verge. The study centers on a 25-year-old Slovenian woman who became pregnant while volunteering in Brazil in February 2015. She developed a high fever and rash during her 13th week of pregnancy, but ultrasounds at 14 and 20 weeks showed no issues. When she returned to Slovenia in October, however, doctors found extensive brain damage in the fetus and the pregnancy was aborted, per NBC News. An autopsy found the full genome of the Zika virus exclusively in the fetus' unusually smooth and scarred brain, suggesting the virus only attacked nerve tissue, per Reuters. The mother had no family history of genetic abnormalities and the fetus tested negative for 13 other viruses known to cause birth defects. "You have a mother who's infected, a fetus that's abnormal, and in the fetus, you have the genetic signature of the virus," says an infectious disease expert. "This is clear data showing Zika can infect the fetus." An epidemiologist adds "it sounds like a pretty clear case of extreme microcephaly." Scientists suspect brain development may have stopped around 20 weeks, leading one doctor to suggest that Zika, like other viruses linked to birth defects, may be most dangerous in the early stages of pregnancy. (The virus has been linked to other health problems.)