FILE: HIV medication. HIV medication

Disappointed researchers reported on Thursday that a second child thought to have been cured of HIV is showing signs of infection.

The patient, a boy born born at a hospital in Milan in December 2009, had only stopped treatment for two weeks when his viral load surged from being undetectable to 36,840 copies per mL.

The news was especially devastating because -- unlike the child in Mississippi who missed treatments because her mother did not bring her back to for followup visits -- doctors in this case stopped the anti-retrovirals on purpose.

The boy, who began receiving aggressive therapy within 12 hours of his birth, was being closely monitored and continued to test negative for HIV on even the most sensitive tests since he began treatment. Writing in this week's edition of the journal Lancet, his doctors said that at the time the child was around 3 years old, they determined that treatment might no longer be necessary, given the results and in view of "recent reports of apparent cure of HIV infection."

The Mississippi baby made headlines last fall when a study about her apparent cure was published in The New England Journal of Medicine. In a phone interview, Mario Clerici, a professor at the University of Milan and a co-author of the study, said the mother of the boy in the Lancet study read stories on the Internet about the Mississippi case and asked clinicians to stop her own child's therapy. HIV treatments can have a number of serious, long-term side effects, including damage to bones, liver and heart and she felt that if they could avoid subjecting her child to those risks they should, Clerici said.

"We had a long discussion and we also spoke with all our colleagues around the world, and we all said it looks like the Mississippi baby is cured, so let's do it. Unfortunately, it was not the reality," Clerici said.

One week after stopping treatment, the child still appeared to be cured, but two weeks later the child's viral load rebounded and the team restarted anti-retrovirals. By the third week, the boy's his viral load appeared to be under control and fell to low levels, but other tests for HIV turned positive. Clerici said the child's viral load has since returned to undetectable levels and that researchers are watching to see if the child will be able to clear all signs of the virus again with continued treatment.

In July, U.S. government researchers announced what Clerici and his colleagues already feared -- that the Mississippi baby had also not been cured. In a routine clinical visit, researchers found that girl, who was nearly 4 years old at the time and had been off of treatment for more than two years, had detectable levels of the virus.

A third baby who was thought to be cured and who was born near Los Angeles has not stopped treatment and remains free of the virus. Scientists now believe that reservoirs of HIV may be hiding in the body even when the virus appears to be gone, but can't be detected by current testing methods.