Understanding historical rates of disease could be very useful for those working to control the same diseases today. Unfortunately, detailed epidemiological record-keeping is a recent invention. However, the coincidence of two remarkably detailed studies of the city of Chester and its surroundings in the 1770s have given scientists a unique snapshot of the era, and give reason to be thankful for modern medicine.
The UK didn't start conducting regular censuses until 1801, and most other nations were considerably later. Consequently, even in the rare cases where we have detailed figures on infection rates, we don't know what proportion of the population these represent.
However, Professor Simon Szreter of Cambridge University found a rare exception. In 1774, a Chester physician named John Haygarth conducted his own census of the town and surrounding countryside to calculate local rates of disease. More than 200 years later, Szeter learned that Chester Infirmary's admissions register from 1773-1775 survives, allowing a direct comparison. Previously, the earliest data we have had of similar reliability was from 1911-12.
"We have just enough information from Haygarth to reconstruct the most probable age structure of the City of Chester in 1774 – the middle of the three years for which we also have detailed information about who was entering the infirmary and why," Szreter said in a statement.
Although the register doesn't distinguish between syphilis and gonorrhea, the two main sexually transmitted diseases of the era, Szreter sorted cases based on the length of treatment. The symptoms of syphilis – including genital sores, faces eaten away, and dementia – were so dreadful that, pre-penicillin, treatment involved five weeks application of mercury, which could cause dementia even when it didn't kill.
Poets of the day contrasted disease-riddled cities with a romantic view of the countryside, and Szreter reports in Continuity and Change that there was something to this. Within Chester itself, 8 percent of residents under the age of 35 had syphilis, while in the surrounding countryside the rate was less than 1 percent. Penicillin almost wiped syphilis out in England, but last year saw the highest rates since 1949.
Besides demonstrating the importance of safe sex campaigns and controlling antibiotic resistance, the work could contribute to our understanding of the influence of disease on demographic change in one of the birthplaces of the Industrial Revolution.
By coincidence, Szreter is at St John's College, where Haygarth studied. "Not many academics have the chance to collaborate in their research environment with an eminent member of their own College who died over 200 years ago,” Szerter said. He is hopeful that Hogarth's patient records, described as having been extremely detailed, will eventually resurface, which he said would be like “finding Richard III in a car park.”