WASHINGTON, July 10 (Xinhua) -- U.S. health officials announced Thursday that the child known as the "Mississippi baby," an infant seemingly cured of HIV, now has detectable levels of the virus after more than two years of not taking antiretroviral therapy, dashing hopes of a possible cure that has generated great expectations.
"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," Anthony Fauci, director of the U. S. National Institute of Allergy and Infectious Diseases (NIAID), said in a statement.
"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," Fauci said.
The child was born prematurely in a Mississippi clinic in 2010 to an HIV-infected mother who did not receive antiretroviral medication during pregnancy and was not diagnosed with HIV infection until the time of delivery.
Because of the high risk of HIV exposure, the infant was started at 30 hours of age on liquid, triple-drug antiretroviral treatment.
The baby continued on antiretroviral treatment until 18 months of age, when the child was lost to follow up and no longer received treatment. Yet, when the child was again seen by doctors five months later, blood samples revealed undetectable HIV levels.
The child continued to do well in the absence of antiretroviral medicines and was free of detectable HIV for more than two years.
However, during a routine clinical care visit earlier this month, the child, now nearly 4 years old, was found to have detectable HIV levels in the blood, the researchers said, adding that further tests performed 72 hours later confirmed this finding.
Genetic sequencing of the virus indicated that the child's HIV infection was the same strain acquired from the mother, they said.
"Based on these results, the child was again started on antiretroviral therapy," the NIAID said. "To date, the child is tolerating the medication with no side effects and treatment is decreasing virus levels."
HIV experts said that doctors must now work to better understand what enabled the child to remain off treatment for more than two years without detectable virus and what might be done to extend the period of sustained HIV remission in the absence of antiretroviral therapy.
"Typically, when treatment is stopped, HIV levels rebound within weeks, not years," said Deborah Persaud, professor of the John Hopkins Children's Center in Baltimore and one of the experts involved in the ongoing analysis of the case, calling the fact that this child was able to remain off antiretroviral treatment for two years "unprecedented."
"The case of the Mississippi child indicates that early antiretroviral treatment in this HIV-infected infant did not completely eliminate the reservoir of HIV-infected cells that was established upon infection but may have considerably limited its development and averted the need for antiretroviral medication over a considerable period," said Fauci.
"Now we must direct our attention to understanding why that is and determining whether the period of sustained remission in the absence of therapy can be prolonged even further," he said.
It's the second time that doctors have reported disappointing news on HIV cure research in the past one year, a fact that shows HIV is still far from being beaten.
Last December, Boston doctors also reported the return of HIV in two men who appeared to have cleared the virus after undergoing bone marrow transplants.
At that time, the lead scientist, Timothy Henrich of Brigham and Women's Hospital, told Xinhua that the reemergence of the virus demonstrates that HIV reservoirs, latent cells carrying the virus, "is deeper and more persistent" than scientists had realized.
"Through this research, we have discovered ...that our current standards of probing for HIV may not be sufficient to inform us if long-term HIV remission is possible if antiretroviral therapy is stopped," he said.
Currently, Timothy Brown, also known as "the Berlin Patient," is thought to be the only individual functionally cured of HIV. Originally from Seattle, Brown was pursuing his studies in Berlin, Germany when he was diagnosed with HIV in 1995. He has shown no signs of HIV in his blood since receiving a bone marrow transplant in 2007 to treat leukemia.