In March last year, doctors announced that a girl in Mississippi who was born with HIV and treated with antiretroviral drugs about 30 hours after she was born, had been cured of HIV infection.

The development raised the possibility of an effective treatment that could reverse infection in young children living with HIV and even adults who have just contracted the AIDS-causing virus. The girl remained virus-free the last two years regardless that she stopped taking HIV medications when she reached 18 months old.

The latest update on the girl's case, however, deflated optimisms. On Thursday, federal health officials revealed that the girl, who is now 4 years old, is exhibiting signs of HIV infection. Results of a blood test taken during the girl's routine clinical care visit this month showed that the girl has detectable level s of HIV in her blood. Additional tests also revealed that the girl has reduced white blood cell count as well as HIV antibodies, which are indication of an infection.

"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," said National Institute of Allergy and Infectious Diseases (NIAID) director Anthony S. Fauci. "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. The NIH remains committed to moving forward with research on a cure for HIV infection."

Based on the results, the child, who has stopped taking HIV drugs for over two years but continues to receive monitoring, treatment and medical care, is now back on an antiretroviral therapy.

The girl, who is known as the "Mississippi baby" was born premature in 2010. She contracted her infection from her mother who was not diagnosed with HIV nor given antiretroviral medications during her pregnancy.

Because the child was found to be at elevated risk of HIV exposure at birth, she was given liquid, triple-drug antiretroviral treatment in as early as 30 hours after her birth. A test confirmed several days later that she was infected but continued receiving therapy until she was 18 months when she was lost and could not receive treatment.

When the child was seen five months later, medical staff found that her blood samples had no detectable levels of HIV or HIV specific antibodies. The child also appeared to be HIV free for over two years despite the absence of antiretroviral medicines.