Pauline Cafferkey is showing signs of improvement and remains in isolation at the Royal Free hospital in London

British nurse Pauline Cafferkey, who contracted Ebola in Sierra Leone, is showing signs of improvement and is no longer critically ill, the Royal Free hospital in London has said.

The Scottish public health worker remains in isolation at the hospital where she is receiving specialist care. She was diagnosed with Ebola after returning to Glasgow and was admitted to the city’s Gartnavel hospital on 29 December before being transferred to the Royal Free the following day.

Cafferkey, from Cambuslang in south Lanarkshire, had volunteered with Save the Children at the Ebola treatment centre in Kerry Town before returning to the UK.

The charity has launched an investigation into how the nurse was infected but admits it may never establish the exact circumstances.

Cafferkey flew back to the UK via Casablanca in Morocco. Her temperature was tested seven times before she flew from Heathrow to Glasgow and she was cleared to travel. She later became feverish and followed advice given to her at Heathrow to contact local services and was admitted to an isolation facility at the Brownlee unit in Gartnavel hospital. After a blood sample tested positive for Ebola, Cafferkey was transferred in a military plane to the Royal Free on 30 December.

Her relatives said last week: “We would like to thank all our friends, family and the members of the public who have contacted us with support following Pauline’s diagnosis with Ebola. We have been very touched by the kind words.”

They thanked those working at the hospital, adding: “We want to thank all the staff caring for her for their kindness, support and compassion.”