US Centers for Disease Control, 'Ebola unprecedented'

"The current outbreak is a crisis. It is unprecedented," said Tom Frieden, the Centers for Disease Control, or CDC, chief while testifying before Congress. "At the current trend, within another few weeks there will have been more cases in this outbreak than in all previous recognized outbreaks of Ebola put together." More than 1,700 people have been infected with the disease in four West African countries – Liberia, Guinea, Sierra Leone and Nigeria – and almost 1,000 have died as a result, according to the World Health Organization, or WHO. Frieden cautioned that those figures might not accurately reflect the realities of the outbreak.  "The lack of treatment facilities, the lack of laboratory facilities make it so that the data coming out is kind of a fog-of-war situation, if you will, and that's one thing that we want to try to resolve quickly," he said. The CDC activated its highest alert level, Level 1, on Wednesday in response to the outbreak. The health institute will have at least 50 staff in the region in the coming weeks to combat the health crisis. More than 200 CDC staffers are currently working to stop the outbreak with more to be added "in the coming days and weeks," said Frieden.

"We can stop Ebola. We know how to do it," he said. "We have to stop it at the source in Africa. That's the only way to get control."

There is currently no known cure for Ebola, a hemorrhagic fever that has a fatality rate of up to 90 percent, according to the WHO. The disease is spread via body fluids of infected persons.

Infected persons do not typically display symptoms of the disease until two days to three weeks after they have been infected.

The U.S. is currently using an experimental drug called ZMapp to treat two American health workers who were infected with the disease while trying to stop the outbreak in Liberia.

They are reportedly showing improvements in their health.