US on highest-level alert over Ebola outbreak

The director of the U.S. Centers for Disease Control and Prevention (CDC) said Thursday he has activated the level of the agency's response to the West African Ebola outbreak to its highest alert status.

"I have activated the CDC Emergency Operation Center at level one for this outbreak. This is our highest level of response," CDC Director Tom Frieden told a congressional hearing. "It doesn't mean that there's an increased risk to Americans, but it does mean that we are taking an extensive effort to do everything we can to stop the outbreaks."

Calling it "a crisis" and "unprecedented," he said at the current trend there will have been more cases in this outbreak than in all previous recognized outbreaks of Ebola put together " within another few weeks."

And the best way to protect everyone worldwide is to stop the outbreak at the source in today's interconnected world, Frieden said.

"That is the only way to get control," he said. "I am confident that if we do what works, we will stop this one. But it won't be quick and it won't be easy. It requires meticulous attention to detail, because if you leave behind even a single burning ember, it's like a forest fire. It flares back up."

Ebola, a severe disease that first emerged in 1976, kills up to 90 percent of those who are infected with it. This time, the average fatality rate is estimated at 55 percent.

While there is no known cure for the disease, two U.S. aid workers diagnosed with Ebola while treating patients in Liberia are reportedly both feeling stronger after receiving an experimental drug called ZMapp, developed by a U.S. company called Mapp Biopharmaceutical.

That has raised questions about whether the untested and unapproved drug should be used in the outbreak. The World Health Organization said Wednesday it will convene a panel of medical ethicists early next week to review the experimental treatment.

Frieden, however, said that it's too early to tell if the treatment is effective.

"The plain fact is that we don't know whether that treatment is helpful, harmful or doesn't have any impact," he said. "And we're unlikely to know from the experience of two or a handful of patients whether it works."