There could be up to 10,000 new Ebola cases per week in Guinea, Liberia and Sierra Leone by the end of this year as the outbreak spreads, the World Health Organization warned Tuesday.

And now that a nurse has become the first person to contract Ebola on American soil, the Centers for Disease Control and Prevention says it has a new plan to help hospitals handle the deadly virus.

"For any hospital anywhere in the country that has a confirmed case of Ebola, we will put a team on the ground within hours," CDC Director Dr. Tom Frieden told reporters.

The response team will include experts in infection control, protective equipment and experimental therapies. A team such as that, Frieden said, might have prevented a Dallas nurse from contracting the disease. The nurse was a member of the medical team that treated an Ebola patient who died last week.

"I wish we had put a team like this on the ground the day the first patient was diagnosed. That might have prevented this infection," Frieden said. "But we will do that from this day onward with any case anywhere in the U.S."

In addition to the many experts it sent to Dallas, Frieden said, the CDC "could have sent a more robust hospital infection control team and been more hands-on with the hospital from day one about exactly how this should be managed.

"Ebola is unfamiliar. It's scary," said Frieden. "And getting it right is really, really important, because the stakes are so high."

Speaking to reporters in Switzerland, WHO Assistant Director-General Dr. Bruce Aylward told reporters that the Ebola outbreak could get worse before it gets better. By December, he said, there could be between 5,000 and 10,000 new cases weekly in West Africa.

Compare those December projections to the latest figures. As of Tuesday morning, there were a total of 8,914 Ebola cases and 4,447 deaths reported to the WHO, Aylward said.

The outbreak's mortality rate, he said, is about 70%.

"This has been a deadly disease ever since we discovered it in 1976," said Dr. Seema Yasmin, a staff writer at the Dallas Morning News and a former CDC disease detective.

"Certainly the death rate can be lowered if we don't have any delays in diagnosis and don't have any delays in treating people," Yasmin told CNN's Wolf Blitzer.

Aylward told reporters that in 90 days, officials have a goal they're aiming for: They want to see the number of cases dropping from week to week.

To start to decrease the rate of infection, the WHO says it hopes to isolate 70% of Ebola patients and have 70% of Ebola victim burials performed safely by December 1. Getting responders, facilities and plans in place to meet the goal will be very difficult, Aylward said.

Missing the goal will mean that more people will die than should have and that even more resources will be needed because the infection rate will continue to climb, he said.