The girl was given a combination of three antiretroviral drugs 30 hours after her birth in an attempt to control the virus.
At about 18 months old, the girl's mother took her off the medication and for another year and a half she showed to have no significant amount of the virus in her blood.
"Certainly, this is a disappointing turn of events for this young child, the medical staff involved in the child's care, and the HIV/AIDS research community," NIAID Director Dr. Anthony Fauci said in a statement. "Scientifically, this development reminds us that we still have much more to learn about the intricacies of HIV infection and where the virus hides in the body."
Doctors put the girl back on the antiretroviral drugs.
"It felt like a punch to the gut," said Dr. Hannah Gay, a pediatric HIV specialist at the University of Mississippi Medical Center . "It was extremely disappointing from both the scientific standpoint ... but mainly for the sake of the child who is back on medicine and expected to stay on medicine for a very long time."