A baby girl in the US born with HIV and believed cured after very early treatment has now been found to still harbour the virus.
Tests last week on the four-year-old child from Mississippi indicate she is no longer in remission, say doctors.
She had appeared free of HIV as recently as March, without receiving treatment for nearly two years.
The news represents a setback for hopes that very early treatment of drugs may reverse permanent infection.
Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told US media the new results were “obviously disappointing” and had possible implications on an upcoming federal HIV study.
“We’re going to take a good hard look at the study and see if it needs any modifications,” he said.