"We will stop Ebola in its tracks in the U.S.,” Dr. Tom Frieden, director of the Centers for Disease Control and Prevention, says confidently, over and over. But how can we be sure?

Many Americans are mistrustful. “Sorry I am not confident in their confidence that it won't spread... that is what they told us when they brought the 3 infected folks here... it will spread it is just a matter of how fast,” Wendy Head-Chapman writes on NBC News Health's Facebook page. “Government can’t be trusted,” chimes in Janet Calderone McElroy.

But the CDC knows it does not pay to lie to people about disease, says Dr. Tom Inglesby, director of the University of Pittsburgh Medical Center’s Center for Health Security, a think-tank dedicated to health threats.

“They know it would be a terrible mistake for the institution, a terrible strategy, and they just won’t do it,” Inglesby told NBC News. “People are learning what is known by the CDC when the CDC learns it.”

It is difficult to reconcile the image of Ebola spreading out of control in Liberia, Sierra Leone and Guinea with the message that a patient sick with Ebola is unlikely to cause an outbreak in the United States. It’s made more than 7,000 people sick so far — probably far more — and killed 50 to 70 percent of them. Even the World Health Organization says it’s going to worsen exponentially.

But experts both in and out of the CDC say they know plenty about Ebola, how it spreads and what the danger to the general public is. Most outbreaks in Africa have been quickly contained. This one turned into an epidemic because of a terrible combination of factors — countries devastated by years of civil war, a complete lack of public health infrastructure and a public that had never heard of Ebola and had no idea how it spread.

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People are dying in the streets, patients are turned away from overflowing hospitals to take their own chances, caregivers must tend to loved ones without any protections, sometimes even without running water and soap.

None of those things happens in the United States, with its modern, if imperfect, public health system.

Hospitals are alert to the risk of someone coming in with many different infectious diseases, not just Ebola but also tuberculosis, influenza, measles. They know to quickly isolate or at least segregate patients who are coughing, sneezing, vomiting or who have diarrhea. Health care workers examining such patients wear gloves, masks and often gowns.

Hospitals have disinfectants to clean up anything that might get contaminated and health workers know the drill for what to do if they do come into contact with someone who might have infected them. With Ebola, they know to watch for fever and to isolate themselves if they do start showing similar symptoms.

U.S. hospitals have successfully dealt with imported infectious diseases, including Middle East Respiratory Syndrome (MERS) and several patients with Lassa fever, which is another dangerous viral hemorrhagic fever similar to Ebola. And even if hospitals do mess up — outbreaks of Methicillin resistant Staphylococcus aureus (MRSA) or Clostridium difficile (C. diff) are examples — Ebola is much easier to kill than these bacteria.

That's true even though it appears a Dallas-area hospital at first mistakenly sent Ebola patient Thomas Eric Duncan home when he came in seeking treatment.

Dr. David Heymann of the London School of Hygiene and Tropical Medicine, and a leading world expert on disease outbreaks, agrees. “U.S. hospitals have good infection control measures in place, which involve isolating fevers of unknown origin, and using good clinical practices. It is also fairly easy and straightforward for U.S. authorities to trace any contact the patient may have had, and to put contacts under fever surveillance,” he said.

“So as long as these systems are maintained, we don't need to worry about a major Ebola outbreak occurring in the US. The same activities that will contain Ebola in the US will also stop the outbreaks in Africa if applied effectively.”

CDC has a track record of handling disease imports and actual pandemic without lying, Inglesby points out.

“The team they have there is a group of veteran public health professionals that have been doing this for a long time, working on SARS and bird flu and 2009 H1N1 (influenza) and MERS. There isn’t any evidence from any of those outbreaks in the past that CDC would sit on something to prevent people from panicking,” Inglesby said.

Frieden correctly predicted that someone would show up at a U.S. hospital with Ebola, and he's been quick to say that it's very possible the Dallas patient will have infected someone else.

When H5N1 bird flu first became a big threat in 2003, government health agencies did a full-court press on learning how best to communicate threats to the public. One overlying message was that lying always backfires.

“There is a body of research that says the more the public knows, the more it does something that is rational,” Inglesby said.

“In the late 1990s and moving up to 2001 there were a lot of government agencies where you would hear leaders say things like ‘the public must be handled like this,’ like it was a group that must be controlled,” Inglesby said. “But now we know that people can handle information. They need to know true information, and you need to tell them what you don’t know. If you give the public that information, they act like adults.”