A nurse at a British hospital has become infected with acquired immune deficiency syndrome (AIDS) virus after accidental exposure to blood from a patient with the disease, according to a report in a forthcoming issue of the medical journal Lancet.

"That is the first documented case of infection with the AIDS virus from an AIDS patient to a health-care worker in the world," said Dr. Harold Jaffe of the federal Centers for Disease Control. He cautioned that no cases in this country have been fully documented and emphasized that the risk to health-care workers still appears to be "very, very small."

"We continue to believe that AIDS patients can be cared for safely, exercising a reasonable amount of caution," particularly in handling blood, Jaffe said. Concerned about possible negative reactions from U.S. health workers, the CDC has notified state health officials of the British case.

The exposure occurred three months ago and, after a flu-like incident, the nurse appears fine, he said. But because AIDS has a long incubation period, it is too early to tell whether actual disease will develop. "From what we know, chances are that nothing will happen," he said.

The CDC confirmed that the AIDS virus was present in the worker's blood and was told by British researchers, who have not been identified, that an investigation showed that the nurse did not appear to have any risks of getting the disease other than exposure to AIDS blood after accidentally being stuck with a needle.

The British case follows a report earlier this week that AIDS was found in a Boston medical technician who drew blood specimens from patients with high risk of incurring the disease. The CDC's investigation is just beginning, and "we're not exactly sure why" the worker developed AIDS, Jaffe said.

He said the British case was better documented but noted that in this country the CDC has studied more than 300 health workers exposed to potentially infectious material from AIDS patients, largely through needle sticks, and thus far "none of them has developed signs or symptoms suggestive of AIDS."

There is also no evidence of the AIDS antibody, a sign of infection, as was the case in the Lancet report.

As of Monday, the CDC had reported 7,181 cases of AIDS in the United States, including 3,388 fatalities. Although it is not surprising that a health-care worker would eventually become infected, the Lancet report noted that it is surprising that it would be found in Britain first since only about 100 AIDS cases have been reported there.