Friends of Medicare says it happened at St. Therese Villa in Lethbridge on Sept. 1.
"We found out that last Sunday ... one of the staff of that facility walked into this resident's room and found mice nibbling on her face," Sandra Azocar, executive director of Friends of Medicare, said Monday.
"The lady was in fact bitten and now she's been medically treated for that ... I'm completely horrified. I think it's beyond words. I can't imagine being that lady who had this happen to her."
The woman also has disabilities and would not have been able to move the mice off her face, Azocar said.
"She's doing OK. Emotionally it impacted her and she's on medication to prevent infection."
Azocar said a nest of mice was found in the woman's closet.
Staff at the 200-bed facility operated by Covenant Health first complained about mice about a year ago, Azocar said. She added the care centre, built in 2008, also has had a bed bug infestation for about nine months.
Shelley Murphy, a vice-president of Covenant Health, said the mice allegation was being reviewed.
Murphy declined to provide any details, citing patient confidentially.
"If this happened, what we would do immediately is treat the patient, we would immediately clean up the area," she said.
Covenant Health calls itself Canada's largest Catholic health-care organization with more than 14,000 physicians, employees and volunteers serving in 12 communities across Alberta.
Murphy said a report on the review will be submitted to Covenant Health's chief operating officer, Alberta Health Services and Health Minister Fred Horne.
She acknowledged that St. Therese has had mice problems in the past.
"On occasion, mice do get into buildings. We have traps set at the doors. We make sure that the house keeping is done to a very high standard," she said.
"We have audits to ensure that our standards are being adhered to so that our buildings are kept very clean."
Friends of Medicare questioned whether that is the case.
Azocar said it is unbelievable that this would happen in a wealthy province such as Alberta.
"It's obvious the situation hasn't been dealt with the urgency it requires," she said.
"Even though staff have tried to deal with it, there's no overall plan to deal with these health hazards in a more urgent manner."
The Alberta Union of Provincial Employees, which represents workers at the care home, said it has filed a formal complaint with Alberta Occupational Health and Safety officials about mice and bed bugs at St. Therese.
AUPE vice-president Glen Scott said such pests have been an ongoing concern at the care home.
"Aside from the risk of mice infestation presents to immobile seniors, it also creates concerns about staff and seniors being exposed to droppings, carcasses and nests, which can carry deadly hantavirus," he said.
He said the union wants a formal response from Covenant Health.
The union and Covenant Health have been negotiating a first collective agreement for workers at St Therese for more than a year.
The union said earlier this year the two sides agreed to send the impasse to an arbitration hearing this fall.
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