Aylward added that evidence had also “continued to accumulate” in multiple studies linking Zika to microcephaly, a serious birth defect in which a baby is born with an abnormally small head and brain.
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Friday’s findings are preliminary results from the first study tracking pregnant women in Brazil from the time they were infected, and do not prove that Zika is responsible.
Noting more confirmatory epidemiologic data is still needed from Zika endemic areas, Alyssa Stephenson-Famy, assistant professor at the University of Washington, said: “This is exactly the kind of research that we need to demonstrate a causative link and mechanism between the Zika virus and microcephaly”.
“Mosquito-borne transmission of Zika is really the most common way the virus spreads”, said Dr. Jennifer McQuiston, CDC spokesperson.
Researchers working with lab-grown human stem cells “suspect they have discovered how the Zika virus probably causes microcephaly in fetuses”, reported the journal Cell Stem Cell.
Zika-linked microcephaly reported in Colombia, Venezuela. Three days after they infected all the cells with the Zika virus, 90 per cent of the progenitor cells were damaged. But deaths have been reported from the current outbreaks in the Americas.
Results were released Friday by the journal Cell Stem Cell.
“If those cells die or cannot proliferate normally to generate the normal number of neurons, you can imagine the total brain volume to be smaller”, Mochida said. But it raised alarm when Brazilian health officials reported an apparent surge in babies born with microcephaly, which can signal their brains didn’t develop properly.
Since then, scientists have been trying to find out why and how the Zika virus affects the developing brain and when the fetus is most vulnerable. Zika virus is likely to be transmitted and detected in other countries within the geographical range of competent mosquito vectors, especially Aedes aegypti.
Zika has not been proven to cause microcephaly, but evidence of an association led the World Health Organization to declare the outbreak a global health emergency.
As humans are typically infected by the Zika virus carried by mosquitoes, the scientists also grew the virus in mosquitoes to imitate a real-life scenario in which the virus is carried in a mosquito before infecting a human. “I do not think we will, but we will be prepared for it anyway”, Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, said at an event presented by the Harvard T.H. Chan School of Public Health in collaboration with Reuters.
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There’s no evidence that the cells are employing antiviral responses, which means we don’t know whether or how the virus is being cleared from the precursor cells, said Ming, a neuroscientist interested in brain disorders like microcephaly. But the researchers say that it’s not not Zika either, which is why all of the travel warnings and other precautions issued from the Centers for Disease Control might be worth heeding.
