The Public Health Agency of Canada said in a statement late Tuesday it is finalizing plans to bring the three-person mobile team from Winnipeg's National Microbiology Laboratory home from Sierra Leone.

The team is being recalled after three people staying at their hotel were diagnosed with the Ebola virus. None of the team members had direct contact with those diagnosed, and they are not displaying any signs of illness, officials said.

The team members will remain in voluntary isolation and will be monitored as they travel back to Canada. Those plans have not yet been firmed up, PHAC said.

The United Nations health agency had earlier announced it was pulling staff from a laboratory testing for the Ebola virus in Kailahun, in Sierra Leone, after a Senegalese epidemiologist was infected.

"It's a temporary measure to take care of the welfare of our remaining workers," WHO spokesperson Christy Feig told Reuters, without specifying how long the measure would last. "After our assessment, they will return."

Russian doctor Valentine Safronov stands inside a mobile medical lab donated by the Russian government in Conakry, Guinea, on Tuesday. The WHO has withdrawn staff from a laboratory testing for Ebola virus at Kailahun, Sierra Leone. (Youssouf Bah/Associated Press) The three Canadians were among six workers at the lab.

There will be an investigation to see whether it was a routine infection, or something to do with the lab's processes or equipment, WHO said.

Meanwhile, there are five Canadian staff members with Doctors Without Borders who all remain in Sierra Leone, a representative of the organization said, but it was unclear how many are in Kailahun.

The Ebola virus outbreak in Sierra Leone, Guinea, Liberia and Nigeria is the largest ever with at least 1,427 deaths and 2,615 infected since March.

To date, more than 240 health-care workers have developed the disease and more than 120 have died, according to WHO statistics.

The Senegalese worker is under treatment at a government hospital in the eastern town of Kenema and will be evacuated from Sierra Leone.

"This was the responsible thing to do. The field team has been through a traumatic time through this incident," said Dr Daniel Kertesz, WHO Representative in Sierra Leone, in a release. "They are exhausted from many weeks of heroic work, helping patients infected with Ebola. When you add a stressor like this, the risk of accidents increases."

Protective equipment supply critical

In a commentary published in Tuesday’s online issue of the Annals of Internal Medicine, U.S. doctors called personal protective equipment designed to shield health-care workers from contaminated body fluids of Ebola patients critical, but not enough to prevent transmission.

"If transmission of Ebola is effectively interrupted with the use of barrier protection, why are so many health-care workers in the current outbreak being infected, particularly this late in the epidemic? Two contributing factors include an insufficient supply of [personal protective equipment] and a lack of emphasis on the process of donning and doffing PPE," wrote Dr. William Fischer II from the University of North Carolina at Chapel Hill School of Medicine and his co-authors.

Several other factors contribute, they said, such as:

The difficulty health-care workers face in clinically recognizing Ebola virus infection, which often presents with symptoms including fever, fatigue and diarrhea that mirror more common ailments in sub-Saharan Africa such as typhoid fever and malaria.

Limited supplies of personal protective equipment including gloves, gowns and face masks.

Inadequate training in standard precautions.

Poor public health infrastructure.

Guinea, Liberia and Sierra Leone also have few doctors — fewer than an estimated 0.1 physicians per 10,000 citizens.

Even when health-care workers wear the protective equipment, the commentators said, they are at risk of contamination with infectious fluids if the clothing isn’t removed properly.

The impulse to wipe away sweat in the hot, humid and exhausting environment may also lead to inadvertent infection, they said.

In Abidjan, Ivory Coast, an Ebola awareness campaign is in full swing. (Sevi Herve Gbekide/Associated Press)

The commentators suggest that treatment sites mitigate the risks associated with removing protective gear by providing a separate exit, physically removed from the entrance, to ensure those donning the equipment don’t come into contact with those who may be contaminated, and that a dedicated person stationed at the exit focuses on guiding all health-care providers through each step of removing the equipment.

Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, was in Liberia on Tuesday. He also plans to stop in Sierra Leone and Guinea.



"Lots of hard work is happening, lots of good things are happening," Frieden told a meeting attended by President Ellen Johnson Sirleaf on Monday. "But the virus still has the upper hand."

Frieden told Liberian TV that stopping the spread of Ebola virus "requires tremendous attention to every detail."

In Britain, a volunteer nurse who tested positive for the virus after working in Sierra Leone has been given the experimental drug ZMapp, according to the London hospital that is treating him.

William Pooley, 29, was flown home on Sunday in a specially adapted Royal Air Force cargo plane. He was taken to an isolation unit at the Royal Free Hospital in north London.

Meanwhile, Ivory Coast's football federation said Tuesday that it had been instructed by its government to cancel or move next month's home game against Sierra Leone, one of the most affected countries in the West African Ebola outbreak.

A separate Ebola outbreak emerged over the weekend in Congo.