A mummified ancestor of Boris Johnson did not die of syphilis, shocked scientists have revealed.
Marked ‘Switzerland’s most famous mummy’, the corpse made headlines in 2018 when it was identified as Anna Catharina Bischoff, Johnson’s sixth great-grandmother.
Her remains, found in 1975, contained high levels of mercury – historically a treatment for syphilis – so it was presumed the disease had killed her.
But now an analysis of the microbes in their mummified organs has revealed not syphilis, but high levels of a bacteria previously unknown to science.
‘The initial assumption was based on the presence of mercury in his body, especially in his lungs. This may indicate inhalation treatment for syphilis, as that was the protocol followed at the time,” said microbiologist Mohamed Sarhan of Eurac Research.
“So we analyzed many samples from all the organs in his body to see if we could find traces of DNA from the syphilis pathogen, but we couldn’t,” he said.
“Instead, we found this new bacteria that was highly abundant in brain tissues and correlated with the highest concentration of mercury in the brain.”
Comparison of the mysterious ancient bacteria with the bacteria of today revealed that they contained sets of genes similar to those found in modern bacteria that cause bone lesions and lung symptoms.
The bony lesions, which are visible on Bischoff’s remains, are a known symptom of untreated late-stage syphilis.
Therefore, she may have been misdiagnosed with the sexually transmitted infection, when the true cause of her illness was something unknown.
For Dr. Sarhan, just rule out syphilis as the cause of death.
‘The assumption that she might have died of syphilis can be ruled out even if she had. Late-stage syphilis has very clear signs that she didn’t have it,’ said Dr. Sarhan.
“Also, she died aged 69, so not very young. In addition, she had other health problems. For example, she was overweight and had gallstones, in addition to other issues that are currently being investigated.
“The mercury treatment may have weakened his body and immune system over time, but it wasn’t really the main cause of his death.”
The conclusions of Dr. Sarhan are not without controversy, however.
‘This is the point where we have different opinions. In the final stages of syphilis, you don’t find many bacteria in your body anymore. So it was very difficult to find the ancient genome of the bacterium,’ said Gerhard Hotz of the Natural History Museum in Basel, where the mummy is kept.
’ So it’s not proof that she didn’t — for me personally, I still think she did. Her skull clearly shows signs of syphilis. But we can’t prove it from genomes.
Whatever the case, Bischoff’s disease was certainly considered syphilis in its time. And for the rich widow of a priest, this was a damning diagnosis.
‘Nobody wanted to talk about it. Usually when people died of their social class in Basel there was an obituary written about the person, who they were and so on. We found out about everyone else, but not about her,” said Dr. Hotz.
“So we think she died and was buried quickly and privately in the church.”
He said her diagnosis would have prevented her from using public baths and even being treated in a normal hospital. But it did not necessarily indicate any illicit sexual activity.
Dr. Hotz said scrutiny from the religious community would make a case difficult to hide, and her husband’s letters detailing his own illnesses show no symptoms of syphilis.
“We don’t think it was an affair, neither her husband’s nor hers. But there is another explanation – because she was a priest’s wife, she had to visit the sick, to console them,’ said Dr. Hotz.
“And in Strasbourg, close to where she lived, there was a hospital for syphilis, so we thought she was going there to visit sick people. And if someone has recently been infected, you can easily get infected.’
Bischoff was born into a wealthy family in Strasbourg, France, in 1719. His father, himself a priest, ministered to the city’s Swiss families, but when he died aged 40, the rest of the family returned to their relatives in Basel.
Bischoff’s husband would eventually take over her father’s old job in Strasbourg, and she lived there for over 40 years, having seven children – four of whom survived to adulthood.
Their eldest daughter, also named Anna Katharina, is the fifth great-grandmother of Boris Johnson.
After her husband’s death, Bischoff returned once more to Basel, where she died in 1787.
And when she was buried in Barfüsser Church, the mercury that had been used to treat her slowed her putrefaction and turned her into a mummy.
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