A HISTORIAN has compiled the first statistical study of sexually transmitted infections (STIs) in a city during the 18th century.

The study indicates people in Chester engaged in significantly more extramarital sex than those in the countryside.

Prof Simon Szreter, of St John’s College, University of Cambridge, was able to construct a picture of syphilis rates in Chester and the surrounding countryside in the 1770s by combining two sources from the period.

These were a census carried out by eminent local physician John Haygarth in 1774 – which pre-dates the national census which began in 1801 – and Chester Infirmary’s admissions register, which survives for the years 1773-5.

The study estimates about eight per cent of Chester residents of both sexes had been infected with syphilis before the age of 35.

But the estimated infection rate among under-35s in rural communities within a 10-mile radius of the city was a little under one per cent.

Asked about this disparity, Prof Szreter said: “To the extent that infections are more prevalent in the city of Chester than the surrounding areas, it does suggest there’s less opportunity for non-marital sex in the countryside, or more opportunity in the city.

“But it would be speculative to go further than that.”

He said there was no evidence people in rural communities were less likely to seek medical help, and added there was no suggestion Chester was a “hotbed of prostitution” – noting infection rates were “pretty equal” between genders.

“If you’ve a society where everyone is monogamous and faithful, you have no STIs,” he said.

Chester’s infirmary recorded 177 cases of “venereal distemper” during the three years from 1773 to 1775.

The gruelling treatment process for cases thought to be syphilis, known as “the pox”, took at least 35 days.

It involved the continual, supervised application of mercury, which caused patients to produce pints of saliva, supposedly flushing out the venereal poisons.

Side-effects included swollen gums, mouth ulcers and severe halitosis.

Because of this, Prof Szreter was able to identify likely syphilitic cases at the infirmary depending
on the length of stay among patients reporting a venereal “distemper.”

He then compared the figure with a set of age-specific estimates
about the size of the at-risk population based on Haygarth’s census.

Finally, he was able to make a comparable estimate for the rural population within a 10-mile radius of Chester itself.

These rare findings are limited to the city of Chester, but efforts are ongoing to build a picture for London.

“It is the first time we have had any historical statistical evidence like this for sexual disease rates anywhere in Britain,” Prof Szreter said.

“The demographic story of this period is defined by mortality and fertility, and rates of venereal disease could of course affect both.

“But because we haven’t been able to study the impact of STIs, much of the history of British population change has been written as if there wasn’t any.”

Sources containing usable statistical information about STIs before the start of the 20th century are virtually non-existent, and the rate has therefore typically been regarded as incalculable.

The study, Treatment Rates for the Pox in Early Modern England, is published in the academic journal Continuity and Change.