LONDON - Syphilis is back: The sexually transmitted disease long associated with 19th-century bohemian life is making an alarming resurgence in Europe.

Most cases of syphilis are in men, and experts point to more risky sex among gay men as the chief cause of the resurgence. But more cases are being seen among heterosexuals, both men and women, too.

Syphilis was the sexual scourge of the 19th century and is believed to have killed poet Charles Baudelaire, composer Robert Schumann, and painter Paul Gauguin.

The widespread use of penicillin in the 1950s all but wiped it out in the Western world. In the last decade, however, there have been outbreaks in major cities across Europe, including London, Amsterdam, Paris and Berlin:

In Britain, syphilis cases have leapt more than tenfold for men and women in the last decade to 3,702 in 2006. Among men, the rate jumped from one per 100,000 in 1997 to nine per 100,000 last year.

In Germany, the rate among men was fewer than two per 100,000 in 1991; by 2003, it was six per 100,000.

France had 428 cases in 2003, almost 16 times the number just three years earlier.

In the Netherlands, cases doubled from 2000 to 2004, with up to 31 men per 100,000 infected in Amsterdam.

An upsurge is also being seen in the United States. In 2000, infection rates were so low that the U.S. Centers for Disease Control and Prevention embarked on a plan to eliminate the disease. But about 9,800 cases were reported in 2006.

Experts worry that the disease could rebound in the general population if stronger efforts to fight it are not taken soon. Another concern is that pregnant women with syphilis can pass it on to their babies. Nearly half of all babies infected with syphilis while they are in the womb die shortly before or after birth.

"These increases may lead to increases in diagnoses of congenital syphilis over the coming years," said Kate Swan, a spokeswoman for the Health Protection Agency.

Syphilis is a bacterial disease causing symptoms that include ulcers, sores and rashes. While it is treatable with antibiotics if caught early, extreme, untreated cases can result in dementia or fatally damage the heart, respiratory and central nervous systems.

Advances in treating AIDS may have inadvertently boosted syphilis' spread. After decades of being instructed to use condoms and to limit the number of sexual partners, some people are probably suffering from "safe sex fatigue," said Marita van de Laar, a venereal disease expert at the European disease-control center.