Last Updated Oct 14, 2015 1:44 PM EDT
LONDON -- London's Royal Free Hospital says the condition of a nurse being treated for complications resulting from Ebola has worsened.
"We are sad to announce that Pauline Cafferkey's condition has deteriorated and she is now critically ill," the hospital said in a statement Wednesday. Cafferkey was admitted to the hospital's isolation unit on Friday with what officials described as "unusual late complication of her previous infection."
Cafferkey was treated for Ebola after returning from Sierra Leone last year. She was released from the hospital's high-level isolation unit in January but she suffered a relapse last week and was flown by military plane into London for treatment.
Her family told the BBC she fell ill on Monday, Oct. 5, but a doctor in Glasgow, Scotland, where she lives, sent her home. She was admitted to a local hospital the following day.
Experts say evidence is growing that even among those who survive Ebola, mental and physical health problems can last for years even after the virus is cleared from the bloodstream.
Thousands of Ebola survivors in West Africa are now suffering from long-term side effects of the often-deadly disease.
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After recovering from her Ebola infection last winter, Cafferkey returned to work as a public health nurse in Glasgow.
Just a few weeks ago, she was honored with a Pride of Britain award for her work caring for Ebola patients in West Africa. Along with the other honorees, she visited the Prime Minister's residence at 10 Downing Street in London on Sept. 29.