Zika Virus Tests Offer First Proof It Causes Birth Defects, Shrinks Brains

While researchers are a long ways off from wiping out the Zika virus, new tests have turned up important information on the disease. These new tests have shown researchers beyond a shadow of a doubt that Zika virus is the direct cause of the rash of birth defects that have been plaguing Brazil for the last few years. Scientists in the area have long thought the defects and the virus were connected, but specific tests using Zika and baby mice have proven those theories true.

Zika Virus
[Photo by Mario Tama/Getty Images]The L.A. Times reports that the virus, which used to be considered little more than a pest, is one that crosses the placental barrier and heads straight for a fetus' brain. The birth defects, which include brain shrinkage, show up after the baby has been born and usually show up as a misshapen cranium.

Through the experiment, the researchers have managed to gain some insight into how mothers infected with Zika early on in the pregnancy tend to suffer a much larger effect than those who contracted the Zika virus later on in the pregnancy.

All of the findings on Zika virus, published in the medical journals Nature and Cell Stem Cell, show that when the Zika virus can enter and take hold of the body in the first trimester, the virus makes its way very quickly to the woman's uterus and then to cells that line and normally help protect the placenta. While this protection for the baby is still new, it cannot provide as much protection as it does later in the pregnancy. Among other effects, it also limits the blood flow through the placenta, stunting fetal development.

[Photo by Mario Tama/Getty Images]
[Photo by Mario Tama/Getty Images]If the fetus can survive the first attack from the Zika virus and continues to develop, the disease moves its way up into the infant's brain. This secondary attack is also incredibly damaging as it will wreak havoc on the stem cells that are meant to help the brain become a mature organ. As the Zika virus continues to reproduce at a frightening rate, it kills off some cells and damages other. When all is said and done, the damage can sometimes be seen outwardly and other times the damage can only be found out later as the child is not able to develop normally once it's born.

As the BBC points out, it was Chinese scientists who found the rather undeniable connection, at least in lab rats and mice, to the Zika virus and brain shrinkage. To find this link, the researchers injected the Asian strain of the Zika virus, which is closely related to the one circulating in South America, into the brains of mice fetuses just 13 days after the rat mother's fertilization. Studying the fetuses after injection showed the developing brain was smaller than the healthy, untainted ones. The study showed the disease isn't picky about which cells it attacks, though there are some it is primarily drawn to. When the brain has been infected, all of its cells are going to be a target at one point or another.

It's hoped all of this research on the Zika virus will eventually lead to being able to find and produce a vaccination or some other kind of protection. It appears we're still a ways off from being able to defend fetuses from the Zika virus. The good news is the correlation was found, but the bad news is the Zika virus affects even more developed fetuses in some way, leaving no one safe entirely from the dreaded disease.

[Photo by Mario Tama/Getty Images]