Â鶹ŮÓÅ

As the international epidemic of Zika virus disease has unfolded and led to devastating birth defects for at least 1,300 children in eight countries, an agonizing question has persisted: What is the chance that an infected pregnant woman will have a baby with these defects? Researchers don't yet have a complete answer, but they are slowly homing in on one. The largest study to ever look at the question says the risk of one especially severe type of birth defect is "substantial" — in the range of 1 percent to 14 percent. It also reinforces the understanding that women infected in the early stages of pregnancy face the greatest risk. (5/25)

The nation's top infectious disease doctor doesn't scare easy. But Tom Frieden — the head of the Centers for Disease Control — is deeply worried about the rise of Zika virus, which is spreading across the Americas and causing birth defects in babies. And he's shocked that Congress, which has refused to fund the White House's emergency Zika request, doesn't share his concern. (Diamond, 5/25)

U.S. officials are starting a massive effort to protect American athletes from Zika, even as they are learning more about the mysterious disease in real time. Some members of the U.S. Summer Olympics delegation are already being monitored for the virus as they begin to go to Brazil, the epicenter of the rapidly evolving outbreak. The Centers for Disease Control and Prevention is also assessing the threat that athletes and other travelers to the Games may increase the global spread of the mosquito-borne virus when they return to their home countries. (Sun, 5/25)