Anthony F. Fauci directs the National Institute of Allergy and Infectious Diseases at the National Institutes of Health.

Dramatic advances in the treatment of HIV/AIDS have saved millions of lives around the world. Today, someone in his or her 20s who becomes infected with HIV and starts taking anti-HIV drugs can expect to have a nearly normal life expectancy. This stunning success is tempered by the fact that these lifesaving drugs are not curative. Although the virus can be suppressed, it cannot be eliminated from the body.

This has enormous economic implications, because 35 million people live with HIV and millions more continue to be infected each year. In addition, anti-HIV drugs have varying degrees of toxic side effects, and it is difficult for many people to adhere to lifelong drug therapy. This raises the question: Can HIV be cured? That is, can a person for whom treatment has suppressed the virus to undetectable levels discontinue drugs without the virus rebounding?

One key reason why HIV remains incurable is that, soon after a person becomes infected, a reservoir of HIV-infected cells forms and can hide in various locations in the body, including lymph nodes, the gut and even the brain. Although medicines can suppress HIV, the virus in these latent cells resurges if treatment is stopped. Unfortunately, most adults do not learn they are infected for months or even years, by which time the cache of HIV-infected cells has established a strong foothold. Researchers are working to eradicate this reservoir, or at least to limit it. One theory is that treatment soon after infection could thwart its formation or perhaps make it susceptible to elimination.

The “Mississippi baby” case supports this theory. This child was born prematurely in a Mississippi clinic in 2010 to an HIV-infected mother who had not received anti-HIV therapy during pregnancy. If an HIV-infected mother is adequately treated during pregnancy and delivery, with the amount of virus in her blood suppressed below detectable levels, the chance of her passing the infection to her baby is less than 1 percent. Unfortunately, that didn’t happen in this case.

HIV positive since 1981, Michael Deighan, co-owner of the print shop Nightsweats & T-cells, displays his mid-day pills that he takes daily to battle his illness. (AMY SANCETTA/ASSOCIATED PRESS)

Consequently, the baby was given aggressive anti-HIV treatment when she was 30 hours old. Several days later, highly sensitive testing confirmed that the infant had been infected while in the womb. The baby remained on anti-HIV therapy for 18 months, but treatment was discontinued when the mother temporarily stopped taking part in follow-up care. Still, when the child was seen again five months later, no HIV was detected. The child, now 3, continues to show no evidence of infection and remains off anti-HIV medicines, raising hope that a cure has been achieved.

This remarkable result occurred almost accidentally, because an astute pediatrician had determined that this newborn was at high risk of infection and made the bold decision to immediately place her on a full therapeutic course of anti-HIV drugs. Typically, babies born to untreated HIV-infected mothers are provided fewer anti-HIV drugs at lower doses to prevent infection. This is done to avoid unnecessarily exposing most infants — about 75 percent — who aren’t infected to the potential toxicities of the more powerful therapy. Conventional wisdom has dictated that avoiding more toxic regimens for uninfected babies trumps the benefits of aggressive therapy for infected ones, since infected babies would not be cured in any case.

But the likely cure observed in the Mississippi case has changed that ­risk-benefit ratio, presenting researchers with critical questions. Was the positive outcome an outlier? Or does providing immediate, optimal anti-HIV therapy to newborns at high risk for infection offer the possibility of preventing HIV from gaining a permanent foothold, opening the door to a cure?

The possibility of achieving an HIV cure for thousands of infants is too important not to pursue vigorously. The National Institutes of Health will soon launch a carefully monitored clinical trial in 12 countries, including the United States. The study aims to replicate the results of the Mississippi baby case in other infants exposed to HIV in the womb. It is hoped that this study will prove that immediate treatment for HIV-infected newborns can protect them from a lifetime of anti-HIV therapy, while furthering our understanding of how we might pursue a cure for HIV infection in adults, particularly those who are treated early in their infections.

Meanwhile, we must work even harder to reach all HIV-infected women, especially those who are pregnant, with treatment and care — both for their own health and that of any children they bear.