TORONTO -- A six-month mission that sent Canadian Armed Forces medical personnel to West Africa to help with the Ebola response has wound up, the federal government announced Tuesday.

The Canadian military doctors, nurses, medics and support staff have been working at a British-run Ebola treatment unit at Kerry Town, in Sierra Leone. With a marked drop in new cases, the British government informed Canada it no longer needs additional assistance to run the unit.

"I would like to thank the Canadian Armed Forces personnel for their efforts to help contain the Ebola virus in Sierra Leone," Defence Minister Jason Kenney said in a statement announcing the end of Operation Sirona.

"The military component of Canada's response to this epidemic has been instrumental in our whole-of-government approach to alleviate the human suffering the Ebola virus has caused in West Africa."

The unprecedented outbreak, centred in the West African countries of Guinea, Sierra Leone and Liberia, is believed to have started in late December 2013. Since then there have been over 27,500 cases -- which is more than 10 times the number of all known Ebola cases recorded before this outbreak.

The outbreak has claimed more than 11,000 lives.

Health-care workers -- whose contact with Ebola patients always places them at high risk during outbreaks -- have been particularly hard it. The most recent figures from the World Health Organization suggest at least 872 health-care workers have been infected in this outbreak and 507 have died.

It was to address the needs of that specific population that the Kerry Town treatment unit was opened. The facility, located about 30 kilometres south of Sierra Leone's capital, Freetown, was established to provide high quality care for health-care workers -- local and international -- who contracted Ebola.

Most foreign countries, however, have chosen to fly their citizens home for care if they became infected while working in the Ebola hospitals of West Africa.

The first contingent of Canadians -- drawn from the Canadian Forces Health Services Group -- arrived in Sierra Leone on Dec. 30, 2014, after spending several weeks in Britain learning how to safely care for Ebola patients. Three waves of personnel were sent on the mission, deploying for roughly 60 days each time.

A total of 79 medical and support personnel from the Canadian Armed Forces took part in Operation Sirona.

The mission's arrival in West Africa coincided with a period in which new Ebola cases sharply declined. Still, about 90 health-care workers were cared for at Kerry Town during the Canadian deployment, said Lt.-Col. Colleen Forestier, task force commander for Operation Sirona.

"Despite the numbers dropping very rapidly, health-care workers were still having symptoms that resembled EVD (Ebola virus disease)," Forestier said in an interview from Kerry Town.

"Not all of them that came to Kerry Town treatment unit did get diagnosed with EVD. They may have had symptoms that looked very similar at the outset and got diagnosed with something else. But the facility did continue to fill that niche and requirement."

Forestier said about a quarter of the patients who checked into Kerry Town while the Canadians were there were infected with Ebola.

None of the Operation Sirona staff contracted the disease during their time in Sierra Leone.

"They've been very careful and we've been very fortunate," Forestier said.

She said she was personally proud to have been part of an extraordinary mission that has given Armed Forces medical personnel experience they would not normally acquire.

"We have close to 79 people now who have gone ... through on how to prepare, protect themselves and look after patients in an infectious disease environment. And this particular infectious disease has a high mortality rate," she said.

"I think prior to this there really was limited exposure in the Canadian Armed Forces medical services in how to deal with this type of situation. So, are we better prepared? Absolutely."

Though case counts have declined markedly since last fall, Ebola transmission continues at low levels in Guinea and Sierra Leone. And on Tuesday, Liberia's ministry of health announced they had found a case of Ebola, their first since March.