Last June, five years after he was "cured," reports surfaced that "traces" of the virus had been found in Brown's blood.

Even then, some HIV experts said that doesn't matter, that he's been cured. In fact, many AIDS experts believe Brown has experienced what's called a "sterilizing" cure, meaning the virus has been eliminated from the body entirely.

Routine clinical testing on the Mississippi toddler continues, Gay says.

So far, there is no evidence of the virus.

"On the ultra-sensitive testing, we are occasionally getting signals so we cannot say with certainty that this child is absolutely clear of HIV, but we will continue to follow up with the baby," Luzuriaga said. "We have formed a hypothesis and that is already driving the design of new studies and clinical trials that will help us to answer the question of whether by coming in very early we will be able to treat children for a while and then remove them from therapy."