Researchers from France and Madagascar report in Thursday's New England Journal of Medicine they have found a strain of bubonic plague resistant to most of the antibiotics used to treat and prevent the disease that savaged Europe in the Middle Ages.

Tests also suggest that the antibiotic resistance might easily spread to other strains of the bacteria, which once swept through Europe and parts of Asia in the 14th century killing as much as three-quarters of the population in less than 20 years.The strain, identified as Y. pestis 17/95, was found in a 16-year-old boy living in the Ambalavao district of Madagascar in 1995. He recovered after antibiotic treatments, but laboratory tests showed that the bacteria were resistant to eight different drugs, including those most commonly used to treat the plague: streptomycin, tetracycline and spectinomycin.

The results "provide another grim reminder that emerging infectious diseases and antimicrobial resistance in one location can pose serious problems for the entire world," said Drs. David T. Dennis and James M. Hughes of the U.S. Centers for Disease Control and Prevention.

Other serious diseases, such as tuberculosis and strep, have been gradually developing resistance to antibiotics, a phenomenon that is causing grave concern among doctors. Overuse of antibiotics, including the practice of routinely feeding them to livestock, are believe to be the source of the problem.

While the "Black Death" that swept across the globe in the 1300s has entered history books, the plague itself has never disappeared. Between 1980 and 1994 nearly 19,000 cases were reported to the World Health Organization, 229 of them in the United States.

The disease is spread by the bite of rat fleas. Two to six days after being bitten, victims report that headache, fever, vomiting, aching limbs, weakness and delirium develop. The lymph nodes swell and, if the person is lucky, they burst and then heal. But in some cases, the swollen nodes break blood vessels, causing ulcers. The dark collection of blood under the skin is where the name Black Death comes from.

The disease is most dangerous when the bacteria enter the blood or the lungs. Before the discovery of antibiotics, bubonic plague usually killed within three or four days.

Until now, "drug resistance has not been a recognized problem in treating plague," said Dennis and Hughes in an editorial in the journal.