For years the illness was believed to have been under control in Germany, but new figures show a 22 percent rise in the number of new cases last year compared with the previous year, wrote Die Welt on Sunday.
"We were very surprised, the numbers had been stable for the past years and in 2010 were even relatively low," Viviane Bremer, syphilis expert at the Robert Koch Institute in Berlin told the paper.
The illness, which in the past claimed the lives of prominent Germans such as Friedrich Nietzsche and Heinrich Heine, can if left untreated cause serious damage to the heart or brain.
3700 new cases were recorded in 2011, particularly in big cities such as Cologne, Frankfurt am Main and Berlin.
"We don't know exactly why," said Bremer, who added that the rising numbers could be partially down to people more freqently getting themselves checked for sexually transmitted diseases.
Gay men are particularly at risk of contracting the disease, said Bremer, but she does not believe this reflects any behavioural trends.
"It's mainly men who have sex with men who are affected," she told the paper. "But it would be speculation to conclude from that that reckless behaviour is becoming more widespread."
The problem is that although condoms can help protect against the disease, syphilis causes boils and leasions on the skin which are highly contagious. "Condoms are important, but they don't give 100 percent protection," said Bremer.
German health campaigners are particularly concerned by the links between HIV and syphilis and are calling for educational campaigns to encourage people to get tested more frequently.
Those who often have different sexual partners should have a blood test once or twice a year, Armin Schafberger of the Deutsche Aids-Hilfe health organisation told the paper.
Modern medicine can deal with syphilis much better than in the past, when patients were treated with injections of posionous mercury. Now, if caught early enough, the bacterial illness can be treated with penicillin.