(CNSNews.com) - "We are deeply concerned about this new development," Dr. Tom Frieden, head of the Centers for Disease Control and Prevention, said on Sunday, after a Dallas nurse who treated a Liberian Ebola patient also tested positive for the deadly virus -- the first person-to-person transmission in the U.S.
"We now consider all of the health care workers who cared for the index patient (Thomas Eric Duncan) potentially to have been exposed, and we'll be rostering those individuals and determining which require active follow-up in addition to their self-monitoring," Frieden told CBS's "Face the Nation" with Bob Schieffer.
"We know from many years of experience that it's possible to care for patients with Ebola safely without risk to health care workers," Frieden added. "But we also know that ...even a single breach can result in contamination.
"And one of the areas that we look at closely are things like how you take off the gear that might be infected or contaminated. Another that we'll be looking at closely in-- in the investigation is the-- the interventions that were done to try desperately to keep the index patient alive. This included dialysis and intubation. These are two procedures which can result in the spread of infectious material."
The nurse who contracted Ebola after treating Duncan did wear full protective gear.
"I think the fact that we don't know of a breach in protocol is concerning because, clearly, there was a breach in protocol. We have the ability to prevent the spread of Ebola by caring safely for patients," Frieden said.
He listed for "four things" that CDC is doing now:
"First, is to make sure that that individual (the nurse) is cared for safely and effectively. Second, we're identifying that individual's contacts...Third, we now consider all of the health care workers who cared for the index patient potentially to have been exposed and we'll be rostering those individuals and determining which require active follow-up in addition to their self-monitoring. And, fourth, we'll conduct a full investigation of what happens before health workers go in, what happens when they're there, and what happens in ... taking off their protective equipment, because infections only occur when there's a breach in protocol."
Frieden said CDC is now monitoring "all individuals" (he couldn't give an exact number) who cared for Duncan in Dallas, "and we'll be determining how many of those may potentially have had contact that would have resulted in a breakdown of protocol and possible contamination."
Meanwhile, Texas Presbyterian Hospital in Dallas has shut down its emergency room until further notice, CBS reported, because of staffing limitations. Many staffers are being watched for signs of Ebola. This means ambulances will take patients to other emergency departments.
Speaking on NBC's "Meet the Press," Dr. Anthony Fauci, an infectious disease expert with the National Institutes of Health, said U.S. hospitals "need to reemphasize the importance" of the protocols involved in removing their protective gear.
Although such breaches are "very, very rare," it can happen when a health care worker is "fatigued, they've been working for a long time, and when they take it off, they do something inadvertent, like brushing their face or something like that. I don't know how it happened. The CDC's investigating it, but that's very likely what happened. An inadvertent breach."
Fauci said he's "still quite confident" that there won't be a public outbreak of Ebola in this country -- "because of our ability to reach out, do the contact tracing, and isolate people who are infected."
He also said shutting down flights from West Africa "would be counterproductive."
"We can understand how people might come to that conclusion," Fauci told NBC's Chuck Todd. "But when you look at what happens when you isolate a country, you diminish greatly their ability to handle their own epidemic. If that happens, it very likely will spread to other African countries.
"And the best way to protect Americans is to completely suppress the epidemic in West Africa. If we do that, we wouldn't be talking about this today. So to isolate them, maybe with good intentions, actually can be counterproductive and make things worse."