LONDON (AP) — London's Royal Free Hospital has admitted a Scottish nurse who has already recovered from Ebola twice before for another "late complication" from her last infection with the lethal virus.

In a statement Tuesday, the hospital said Pauline Cafferkey will now be treated by its infectious diseases team. Last December, Cafferkey was treated for meningitis that developed from lingering Ebola virus in her system. She was first infected in 2014 while working in Sierra Leone.

The World Health Organization says in rare instances, Ebola can persist in parts of the body not covered by the immune system, including inside the eye, the brain, the spinal cord or in semen.

WHO spokeswoman Fadela Chaib said Ebola survivors need "comprehensive support" to minimize the risk of further spread, especially via sexual transmission — which has been blamed for some recent flare-ups of Ebola in West Africa.

Scientists said while many patients suffer long-term side effects, Cafferkey's case is unusual.

"It is difficult to know what the likelihood of further relapses are, given the previous unprecedented nature of her situation," said Dr. Nathalie MacDermott, a clinical research fellow at Imperial College London.

Experts have previously suggested that Ebola relapses might be triggered by the immune system, when the body gets distracted fighting another infection. That could give any persistent virus a chance to start replicating.

It's still unclear whether any lingering Ebola might be responsible for survivors' ongoing medical problems or if those can be blamed on the acute illness that patients recovered from earlier. Among the thousands of Ebola survivors in West Africa, many still suffer painful side effects including problems with their joints, eyes and ears.

To date, Ebola has killed more than 11,000 people in West Africa.

Jamey Keaten in Geneva contributed to this report.