New weekly cases of Ebola fell below 100 in three hot spots for the first time since last June, but the hardest part of stamping out the outbreak remains, infectious disease experts say.

The World Health Organization says a combined total of 99 confirmed cases were reported from the three countries in the week ending Jan. 25: 30 in Guinea, four in Liberia and 65 in Sierra Leone.

"The response to the EVD [Ebola virus disease] epidemic has now moved to a second phase, as the focus shifts from slowing transmission to ending the epidemic," the WHO said Thursday.

The outbreak has killed 8,810 people out of 22,092 cases, almost all of them in those three countries.

The latest drop in numbers differs from previous declines, WHO communications officer Tarik Jasarevic said.

"Now there is necessary capacity in these countries to fight the virus. Before there was not enough treatment centres, we didn't have enough trained and equipped teams for safe burials. We didn't have enough surveillance teams in communities. We didn't have enough community engagement. Now all of those elements are there," he said in an interview from Geneva.

Elsewhere on Thursday, a second Canadian Forces medical contingent left CFB Trenton in Ontario to start training in the United Kingdom before its deployment in Sierra Leone.

"The admission rates and new infections rates have been dropping dramatically," Col. David Weger, deputy commander for Canadian Forces Health Services, said before boarding.

"We are optimistic that this may be our last two-month rotation of clinical personnel going in," he said. "We are, however, entirely prepared to do a third one if we need to go the full six months of our current mandate."

The situation has definitely improved since December in Sierra Leone, said Maj. Ian Schoonbaert, a physician with Canadian Forces who will deploy as senior medical authority in Kerry Town, Sierra Leone.

"I think it's time that we make sure we kind of consolidate those victories and help to make sure that it continues to go in a positive manner," Schoonbaert said.

Infectious disease experts stress that tracking down everyone who has had close contact with an Ebola patient is key to ending the outbreak.

Microbiologist Dr. Allison McGeer of Mount Sinai Hospital in Toronto returned 10 days ago from two weeks helping health officials in Liberia. In her five-week trip in October streets were quiet during curfew, but now restaurants have re-opened.   

It's major progress to have the number of cases consistently down in all three countries, McGeer said.

"The hardest part of outbreak is the end," McGeer said, especially for one centred in some of the world's poorest countries.

"If we're not there for them, the outbreak will come back."

Last week, researchers from the Institut Pasteur of Dakar and the Institut Pasteur in Paris reported other signs of progress.

They interviewed patients, their families and neighbours in three regions of Guinea—the capital of Conakry, Boffa, and Télimél, They found in March, hospital transmissions made up 35 per cent of all transmissions and funeral transmissions 15 per cent. From April to Aug. 25, the sources of transmission fell to nine per cent and four per cent, respectively.

Currently, in dozens of remote villages in Guinea, angry residents are blocking access for health workers.

The most intense transmission in Guinea is in Forecariah district, close to the border with western Sierra Leone, the worst Ebola hot spot.

"There have recently been reports of high levels of community resistance to EVD response measures in Forecariah, indicating a need to better engage the community in the response," the WHO said.

With files from CBC's Kim Brunhuber, Marcy Cuttler and Reuters