For just the second time since the global epidemic began, a patient appears to have been cured of infection with H.I.V., the virus that causes AIDS.

The news comes nearly 12 years to the day after the first patient known to be cured, a feat that researchers have long tried, and failed, to duplicate. The surprise success now confirms that a cure for H.I.V. infection is possible, if difficult, researchers said.

The investigators are to publish their report on Tuesday in the journal Nature and to present some of the details at the Conference on Retroviruses and Opportunistic Infections in Seattle.

Publicly, the scientists are describing the case as a long-term remission. In interviews, most experts are calling it a cure, with the caveat that it is hard to know how to define the word when there are only two known instances.