By Rosalind Bentley
The Zika virus is definitely the cause of not only microcephaly, but a range of other severe birth defects of the brain, the Centers for Disease Control and Prevention said Wednesday.
"We conclude that a causal relationship exists between prenatal Zika virus infection and microcephaly and other serious brain anomalies," wrote the four lead doctors of the CDC's Zika response team in a paper published Wednesday in the <i>New England Journal</i> of Medicine.
Zika is the first mosquito-borne virus ever known to cause birth defects.
"Never before in history has a bite from a mosquito caused such a malformation," said Dr. Tom Frieden, CDC director.
It has long been suspected that there is a link between the Zika virus and microcephaly, a condition where babies have unusually small heads and underdeveloped brains. Wednesday's announcement is the first time the CDC has made the direct connection. The correlation to other birth defects heightens the alarm even as warmer weather ushers in mosquitoes which could spread the virus in the United States.
It has been more than half a century since an infectious disease caused an epidemic of birth defects, the last one being rubella, the authors said. While there is a vaccine for rubella, there is no vaccine yet to prevent Zika. While the National Institutes of Health will begin Zika vaccine trials in September, Dr. Anthony Fauci, head of the NIH's Institute of Allergy and Infectious Diseases said earlier this week it could be months if not years before a vaccine is ready.
Zika is transmitted by bite from either the Aedes aegypti or Aedes albopictus mosquitoes, both of which are found in Georgia and nearly 30 other states from California to New York. The disease is also transmitted sexually. The CDC is still advising pregnant women not to go to any region experiencing a Zika outbreak because an infection can occur with a single mosquito bite. Pregnant women or those who want to become pregnant shouldn't have sex with a man who has traveled to regions with Zika outbreaks. Brazil has been the epicenter of the outbreak but other Latin American and Caribbean countries have also seen a surge in infections. For the United States and its territories, Puerto Rico leads in number of infections, now approaching 350.
Researchers at Emory University contributed to the findings. Working with researchers from Johns Hopkins University and Florida State University, the Emory researchers discovered that neural stem cells exposed to the virus begin to die within hours. The remaining neural stem cells not only retain the virus but spread it to other neural cells that eventually form the brain.
"It's attacking at the earliest points of development," said Peng Jin, a genetics professor at Emory University told the Atlanta Journal-Constitution. Jin was one of 15 researchers on the neural report published in Cell Stem Cell journal.
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