A second aid worker is undergoing tests for Ebola in Scotland after returning from West Africa, Scotland's First Minister Nicola Sturgeon confirmed Tuesday. But Sturgeon stressed there was a “low probability” that the aid worker actually has the disease.

“Although this is another returning health care worker from West Africa, the patient here has had no, as far as we’re aware, direct contact with people infected with Ebola,” Sturgeon told BBC Radio, according to Reuters. “This patient over the course of today will be transferred for tests.”

The second patient was staying at a hostel in the Scottish Highlands, but was transferred to Aberdeen Royal Infirmary for testing, the Telegraph reports. The individual had no connection with nurse Pauline Cafferkey, the aid worker who was diagnosed with Ebola Monday in Glasgow.

A third individual is undergoing precautionary testing for the Ebola virus in isolation at the Royal Cornwall Hospital in southwest England, the New York Times reports. Authorities do not expect to have an official diagnosis “for at least 24 hours.” 

Cafferkey, 39, contracted the virus while volunteering with Save the Children to treat patients in the West African nation of Sierra Leone, The Telegraph reports. A fellow aid worker suggested she may have been exposed to the virus during a Christmas service.

Cafferkey was transferred Tuesday morning to an isolation unit at Royal Free Hospital in London. She arrived from Scotland aboard a military plane that contained a quarantine tent. 

“Our thoughts are with the individual, their family and colleagues at this difficult time. We wish them a speedy recovery,” Save the Children humanitarian director Michael von Bertele said in a statement, according to the Telegraph. “Save the Children is working closely with the UK government, Scottish government and Public Health England to look into the circumstances surrounding the case.”

It is the first-ever Ebola case to be diagnosed within the United Kingdom, Sturgeon said Monday. Cafferkey felt sick after her flight Sunday from London Heathrow Airport to Glasgow and checked into a hospital the next morning. She received treatment in Gartnavel Hospital’s Brownlee Center for Infectious and Communicable Diseases until her transfer to Royal Free Hospital.