Within the past year there have been outbreaks of syphilis in Manchester, north London and Brighton. The disease, which had almost disappeared from Britain, can lead to brain damage, disability and even death if untreated.

The worst of the three hot spots was Manchester and the outbreak is even now not at an end. There have been at least 160 cases of syphilis in the city according to genito-urinary medicine clinics that would expect to see one or two.

Around three quarters of the Manchester cases have been in young gay or bisexual men, typically in their twenties or early thirties. The heterosexual cases were thought to be a separate cluster with links abroad. About a quarter had an other sexually transmitted infection as well as syphilis and around a fifth knew they were HIV positive.

What the three outbreaks told public health officials was that fear of Aids was dissipating. The gay men, who had mostly become infected in the Manchester area, were no longer practising safe sex, even though some had HIV. They tended to have many partners. A Manchester health authority report said the men told of heavy use of alcohol, and drugs "with aphrodisiac and disinhibitory effects".

The authority has warned of the dangers through radio interviews, websites and magazines and has distributed thousands of leaflets and condoms. But the lack of early symptoms, together with anonymous sexual contacts, made it difficult to locate those who should be treated.

"Further research is needed into why people seem not to be heeding safer sex advice, particularly in relation to unprotected anal sex," said the health authority report.

"Reasons could include boredom with the messages, people feeling (inaccurately) that HIV is curable, or a new generation having grown up without experience of Aids."