TAPPER: Welcome back to THE LEAD. I'm Jake Tapper. In other unsettling world news, there is no apparent end in sight for the worst Ebola outbreak in history. The World Health Organization today putting the death toll in West Africa at more than 2,000. Here at home another infected American with Ebola, Dr. Rick Sacra, is back in the U.S. for treatment. He's said to be in stable condition in the Nebraska Medical Center's bio containment unit. He was not working directly with Ebola patients. It is still unclear how he contracted the disease. Joining me now from Atlanta, Dr. Beth Bell. She's an infectious disease director at the Centers for Disease Control and Prevention. Dr. Bell, thanks for joining us. We've been told not to worry about Americans being infected who are now back here in the U.S. but the two previous patients, we now how they were infected working with Ebola patients. We don't know how this third patient, this third doctor was infected. Shouldn't we be worried about him being here, given that there is this is mystery about him?</s>DR. BETH BELL, CENTERS FOR DISEASE CONTROL AND PREVENTION: Well, I'm not sure that I would call it exactly a in is industry. You're right, right now, we don't know the exactly how he got infected, but that doesn't mean that the way he got infected is anything unusual. May just be that we need to do a little bit more investigating to find out exactly the cause. You know, we really -- the situation in Africa, in West Africa, is very serious. It's very dire. And it can be very frightening for people. But how Ebola is transmitted is not mysterious. We know how Ebola is transmitted. The way we're seeing cases, people becoming infected in Africa is primarily in two different settings, in households in close contact with people that have Ebola and handling corpses and in health care facilities where health care workers are not using appropriate infection control. So, we do know how Ebola is spread.
Ebola Outbreak: No End in Sight