Dr. Thomas Frieden, director of the Centers for Disease Control (AP Photo/John Amis)

(CNSNews.com) - Dr. Tom Frieden, director of the Center for Disease Control and Prevention (CDC), said during a telephone press briefing Wednesday that you cannot get Ebola by sitting next to someone on a bus, but that infected or exposed persons should not ride public transportation because they could transmit the disease to someone else.

Dr. Frieden also reported that a Dallas health-care worker who has been diagnosed with Ebola had a temperature of 99.5 when she flew from Cleveland to Dallas on Monday.

Frieden’s statement came in response to CNSNews.com’s question regarding a video message from President Barack Obama last week addressing Ebola-stricken countries in West Africa, in which the president told residents they “cannot get [Ebola] through casual contact like sitting next to someone on a bus.”

During the conference call, CNSNews.com asked Frieden: “In a video message to countries in West Africa that are experiencing Ebola outbreaks, President Obama told residents they cannot get the disease by sitting next to someone on a bus. But CDC recommendations state that travelers in West Africa who begin to show possible symptoms, or people who have experienced a high risk of exposure, should avoid public transportation, including buses. And we’ve also seen large amounts of concern regarding potentially infected people traveling on airplanes.

“My first question is, did the CDC vet this video message before it was released and posted on U.S. embassy websites, and is it true that a person runs absolutely no risk of contracting Ebola on public transportation, such as a bus?”

“Yes, CDC vetted the message, and, yes, we believe it’s accurate,” Frieden responded.

“I think there are two different parts of that equation,” he continued. “The first is, if you’re a member of the traveling public and are healthy, should you be worried that you might have gotten it by sitting next to someone? And the answer is no.”

“Second, if you are sick and you may have Ebola, should you get on a bus? And the answer to that is also no. You might become ill, you might have a problem that exposes someone around you,” he said.

Frieden also reiterated that the CDC is currently tracking down and monitoring those who were on the same flight as a health care worker just before she was diagnosed with Ebola.

“Because the risk is so low, we think there is an extremely low likelihood that anyone who traveled on this plane would have been exposed, but we’re putting into place extra margins of safety and we’re contacting everyone who was on that flight,” Frieden said.

Earlier in the briefing, Dr. Frieden had pointed out that CDC guidelines indicate that someone who has had exposure to Ebola should not travel on public transportation.

"Because at that point she was in a group of individuals known to have exposure to Ebola, she should not have traveled on a commercial airline,” Frieden said. “The CDC guidance in this setting outlines the need for what is called 'controlled movement.' That can include a charter plane, that can include a car, but it does not include public transport.

"We will from this moment forward, we will ensure that no individual who is being monitored for exposure undergoes travel in any way other than controlled movement,” he said.

Immediately following Frieden’s response to CNSNews.com, a reporter with the New York Post asked Frieden about the CDC’s monitoring of other health care workers who treated the first Ebola patient in the United States, Thomas Duncan.

“How going forward will it be possible to stop people that treated Mr. Duncan from getting on public transportation?” the reporter asked.

“In terms of controlled movement, that is something that we work out with the state and local public health authorities,” said Frieden.

“At this time, we require anyone who may have been exposed to travel by ‘controlled movement’ only,” he said. “The health-care worker No. 2 who travelled from Ohio on the 13th of October, Monday, should not have travelled, should not have been allowed to travel by plane or any public transport by virtue of the fact that she was in an exposed group. And although she did not report any symptoms and she did not meet the fever threshold of 100.4, she did report at that time that she took her temperature and found it to be 99.5.

“So, by both of those criteria, she should not have been on that plane,” said Dr. Frieden.

But despite claiming the health care worker should not have been on the flight in the first place, Frieden added, “I don’t think that changes the level of risk of people around her.”

“She did not vomit, she was not bleeding, so the level of risk of people around her would be extremely low,” he continued. “But because of that extra margin of safety, we will be contacting them all.”

The update comes more than a week after President Barack Obama issued a video message to Ebola-stricken countries in West Africa, telling residents they "cannot get [Ebola] through casual contact like sitting next to someone on a bus." The message has been widely circulated online and is currently posted on multiple U.S. embassy websites.

On Tuesday, a spokesperson for the CDC told CNSNews.com that it’s “not impossible” to contract Ebola from an infected person on a bus, particularly if the healthy person touches a contaminated object.

“It’s very unlikely,” CDC Spokesperson Kristen Nordlund explained. “But if, say, someone was sweating or had blood and touched a handrail and then you touched it right after, and put your hand in your mouth, it is possible. It’s not impossible.”

“Also if the person vomits on you, that can’t be ruled out,” Nordlund continued. “But to get it that way, there’s not a high likelihood of that happening.”