A British nurse who survived Ebola is now back in hospital, with complications from the disease.

Pauline Cafferkey caught the virus in Sierra Leone, when she was working as a volunteer.

She was declared clear after treatment in London nine months ago, but fell ill again this week.

Microbiologist Mark Weber says Ebola can sometimes linger in the body, long after a patient seems to have recovered.

"It does appear that the virus is able to lurk in parts of the body and persist in parts of the body where the immune system doesn't reach."