Reported HIV rates have recently climbed to levels unseen in Hong Kong since the mid-1980s. Despite condom advertisements and poster campaigns plastered from one end of the city to the other, it is tragically obvious that safe-sex messages are still going unheeded – especially by young people. Syphilis – largely eliminated by the 1950s due to the introduction of penicillin – has experienced a dramatic parallel resurgence.

Comparisons can be drawn between currently spiralling HIV infection rates and the late 19thcentury global syphilis crisis. Syphilis, then, was as feared as HIV/Aids was a century later, and for similar reasons. Those infected became ill for a short period and then recovered to more or less full health; meanwhile, the disease stealthily crept through their systems. Then – like full-blown Aids – syphilis suddenly and horrifically erupted. All manner of awful secondary infections and complications, each more debilitating than the last, overwhelmed and finally killed its victim.

Global economic boom conditions in the last quarter of the 19th century created ideal circumstances for the spread of epidemic diseases such as syphilis. The opening of the Suez Canal, in 1869, massively improved international steamship links as transcontinental railways lengthened – across the globe, more people than ever before were on the move. And if people are mobile, so are their diseases.

Hong Kong, as a major port city, was a global epicentre of disease transmission from early times. The Lock Hospital, which incarcerated venerealdisease patients for treatment, opened in Sai Ying Pun in 1858.

Socially marginalised people are usually the first victims in any disease epidemic. In the late 19th century, prostitution was a significant accelerator for the spread of syphilis, much as homosexual men were the main victims in the 1980s-90s HIV/Aids epidemic.

Global migration meant that more single men were in circulation. Isolated from the social restraints that (for the most part) regulated sexual behaviour in more settled societies, and with more disposable money than they might otherwise have enjoyed, migrant males provided a ready market for commercial sex workers, leading to a greatly enlarged red-light sector.

Maintaining the health and operational efficiency of Hong Kong’s resident British garrison was part of the reason for significant public health precautions. Few soldiers were able to marry until they reached their 30s, as pay was not sufficient to support a family. Prostitutes offered almost the only available sexual outlet, which, in turn, allowed diseases such as syphilis to rapidly spread.

Salvarsan – also known as compound 606, or Arsphenamine – was discovered by German scientist Paul Ehrlich in 1907. Its anti-syphilitic properties were discovered in 1909 by Japanese bacteriologist Sahachiro Hata, and the drug was first successfully used in 1910. By the time the first world war broke out, in 1914 – massively accelerating the global movement of single men – a reliable cure for syphilis existed. By the late 20s, thanks to “Dr Erhlich’s magic bullet”, as Salvarsan was popularly known, syphilis was in global retreat. Within the next few years, the miracle drug had transformed the lives of those infected – in much the same way that combination therapies and effective retroviral medications have revolutionised the treatment of HIV patients and caused Aids cases to plummet.

By the 40s, the discovery of antibiotics hastened the demise of syphilis. But like HIV/Aids in the 21st century, the shortness of human memory has seen syphilis make a vile and rapid comeback.

For more on Hong Kong history and heritage, go to scmp.com/topics/old-hong-kong