Secretary of Health and Human Services Sylvia Burwell said that despite the best efforts of health officials, Americans have to prepare for the reality that there may be more cases of Ebola in the United States.

“We had one case and I think there may be other cases, and I think we have to recognize that as a nation,” Burwell said at a media breakfast hosted by the journal Health Affairs and held at the Washington, D.C. offices of the Kaiser Family Foundation.

Burwell’s comments come as screening of travelers from Ebola-affected countries in West Africa has been stepped up at U.S. airports. On Wednesday, the first patient diagnosed with the virus on U.S. soil died in Texas.

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She expressed confidence in the screening process that has already been in place in travelers' departure cities, but acknowledged that no such system is 100 percent.

“The most important place with regard to taking care of screening is actually at the point of departure,” she said. “And that’s been in place for many months and as we know, we have a case. That case sadly is deceased. But for many months, we did not have a case that entered the country. And we know that that screening has worked in the sense of 80 people have been pulled from the lines in the screening and stopped in the home country. And that’s the most important place to do that.”

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She said that there was a massive effort at preparing the healthcare system to deal with any cases that may arise.

“What’s most important is we know how to contain," she said. "And that is: detect, contact tracing, isolation, and treatment.”

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She said that 8,000 healthcare providers have been on Centers for Disease Control and Prevention webinars and hundreds of thousands of health care workers have been communicating through an alert network.