Pauline Cafferkey has tested negative for the Ebola virus, NHS authorities have said, after she was rushed to hospital for a fourth time since her return from Sierra Leone in 2014.

The 40-year-old nurse underwent further tests under the care of the infectious diseases team at Queen Elizabeth University hospital, Glasgow, where she was taken under police escort on Thursday morning.

A spokesperson for the hospital said: “Following a detailed assessment we can provide reassurance that there is no risk to the public.”

Police Scotland confirmed that they had provided an escort “as a matter of course” for the ambulance taking Cafferkey from her home in South Lanarkshire at 9.30am.

She was in a stable condition and would remain in hospital for a second day, NHS Greater Glasgow and Clyde said in a statement. It read: “Pauline Cafferkey was admitted to the Queen Elizabeth University hospital ... under the care of the infectious diseases unit. Due to Ms Cafferkey’s past medical history, appropriate precautionary measures were taken whilst further investigations were carried out. We are pleased to report that tests for the Ebola virus are negative.

“We will not be issuing further statements and would ask that Pauline’s privacy and right to medical confidentiality be respected.”

Sending my very best wishes to Pauline Cafferkey. She has already suffered way too much - & all for trying to help others. Thoughts with her — Nicola Sturgeon (@NicolaSturgeon) October 6, 2016

Cafferkey, 40, first became ill from the Ebola virus on her return from Sierra Leone in late December 2014. She flew on from Heathrow to her home in Glasgow, where she was admitted to hospital with a fever later confirmed as Ebola infection. She was flown to London’s Royal Free hospital, which has a specialist isolation unit for Ebola patients.

She nearly died, but it was thought the virus had been cleared from her system when she was pronounced out of danger in January 2015. That October, however, she became critically ill again and was readmitted to the Royal Free. Her case astonished experts, as the first in which the virus had lurked in her brain or spinal cord undetected and then attacked again, causing near-fatal meningitis.

She has had long-term problems as a result of the second attack, including muscle weakness in one leg, which has meant she is unable to run as she used to do.

A third admission to the Royal Free turned out to be a false alarm, but the experts have no idea whether the Ebola virus is still lying undetected in her body because too little is known about the virus and the disease.

Three weeks ago, Cafferkey was cleared by her regulatory body, the Nursing and Midwifery Council, which had investigated allegations that she concealed her high temperature at Heathrow on her return from Sierra Leone.

The NMC, which could have struck her off the nursing register, said Cafferkey’s judgment had been compromised by her developing illness and so she could not be held responsible for putting the public in danger. Cafferkey said she reported her high temperature, but was allowed to fly on to Glasgow.