A baby girl thought to have been 'cured' of HIV has had the virus detected in her blood.

The American girl, who is now four, was born to a HIV-positive mother. The child made headlines around the world when she appeared to show no sign of the virus after treatment.

At the time, scientists stressed that it was a 'functional cure', meaning the virus was not totally eradicated. However its presence was reduced to such a low level that it could no longer be detected by tests and the child's body could control the virus without the need for standard drug treatment.

Medical staff at the University of Mississippi are said to be devastated that she has now recently tested positive for HIV.

The child is said to be responding well to antiretroviral medicine.

The girl has received nothing more invasive or complex than commonly available antiretroviral drugs. The difference, however, was the dosage and the timing, with treatment starting less than 30 hours after her birth.