MU researchers: Zika virus strain kills babies in the first trimester

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COLUMBIA - MU researchers discovered the lesser-known strain of the Zika virus, African strain, may affect the placenta in different way than the Asian strain, which caused outbreaks in a number of Latin American nations.

The Zika virus is transmitted by mosquitoes and is most prevalent in places like Central America, South America, Brazil, and Puerto Rico. It has also popped up in limited numbers in the southern United States, most often in people who had recently traveled to affected regions.

Pregnant women who travel outside of the U.S. are more likely to get infected. Zika has been linked to neurological disorders like microcephaly, a condition in which a baby's head doesn't grow to expected sizes.

The Asian strain is more common, and according to MU researchers appears to affect the placenta surrounding the fetus in a different manner than the African strain.

"The African strain is so destructive that it infects the placenta and kills the placenta, and therefore causes pregnancy loss," graduate student and research assistant Megan Sheridan said. "Because without the placenta no pregnancy would be supported."

MU Curators' Professor Michael Roberts said the African strain of the virus is worse because it is potentially deadly for unborn children.

"We suspect that the African strain, should a pregnant woman be infected, that she will lose her baby because at that stage it will be very early," Roberts said. "She might not even be aware she was pregnant when she lost it. In other words, her period might be a day or two late, but it will go unnoticed."

According to Sheridan, the results of the African strain on cells has only been seen in lab testing, not actual humans at this point.

The Asian strain, on the other hand, doesn't kill placental cells as quickly. Instead, researchers found it "lies in wait" until it is transmitted to the fetus, often causing disorders like microcephaly.

Pregnant women need to be aware of their sexual partner's travel history as well, as women can contract Zika from others who have been infected.

"It is possible for the male partner to carry Zika and then sexually transmit it to the mother," Sheridan said. "So that causes other concerns."

Roberts said a little more than 100 African strain of Zika cases have been reported sporadically in the U.S.

The Zika virus doesn't affect women's chances of getting pregnant after a pregancy is terminated due to the disease.