A toddler thought to have been cured of HIV now has detectable levels of the virus in her blood, the child’s doctors and US health officials said.

The Mississippi child’s stunning story, first disclosed at a medical meeting in March 2013, was the first account of an HIV-infected infant achieving what appeared to be a cure after receiving aggressive drug treatment within the first 30 hours of life.

The case raised hopes that more of the roughly 250,000 children who are born each year infected with the human immunodeficiency virus, which causes Aids, might have a shot at a cure.

Those hopes were dashed when the child’s doctors discovered last week that the HIV virus had begun replicating, Anthony Fauci, director of the National Institute of Allergy and Infections Diseases, said at a press conference.

The girl, now 4, was born prematurely in a Mississippi clinic in 2010 to an HIV-infected mother who had received no prenatal care.

After her birth, the child was rushed to the University of Mississippi Medical Centre, where Hannah Gay, a paediatric HIV specialist, decided to take aggressive action, offering the newborn a three-drug cocktail of powerful HIV medications. Normally, children suspected of HIV infection are given a milder course of treatments until tests confirm the infection.

The child remained on treatment for 18 months, then stopped going in for treatment. When she returned to the medical centre some weeks later, the child showed no sign of the virus.

Since March, the child’s progress has been monitored closely, and until last week, she had gone 27 months without treatment.

During a scheduled check-up last week, doctors discovered the virus had begun to replicate. The girl is now being treated with anti-HIV treatments she will likely need to take for the rest of her life unless a cure can be found.