New research reveals Boris Johnson’s mummified Swiss ancestor did not die of syphilis, as has long been believed, but of an unknown pathogen.

In 1787, at 68 years old, a woman called Anna Catharina Bischoff died in Basel, Switzerland. On 20 October 1975, workers were excavating in the Barfüsser Church, a former medieval Franciscan monastery, when they discovered a brick-walled grave chamber in front of the church choir containing two well-preserved coffins sitting on a pile of bones.

One was a simple spruce wood coffin, inside which a female mummy was discovered with her left hand holding her right arm above the wrist. So well preserved was this mummy that her nails and hair were still intact and according to a report on Sky News, staff at the Naturhistorisches Museums Basel described this mummy as “the best preserved” and “most enigmatic” in Switzerland.

1835, when the Barfüsser Church was used as a warehouse (public domain)

Boris’s DNA Identified

In January 2018 a World News BBC team travelled to Basel’s Natural History Museum to report on a breaking story. Experts at Naturhistorisches Museums Basel studied the well-preserved mummy’s DNA and identified it as the corpse of Anna Catharina Bischoff. Furthermore, an analysis of modern DNA samples determined that she was an ancestor of the former Prime Minister of the United Kingdom, and former Mayor of London, Boris Johnson!

It turned out that Bischoff had been buried in a crypt beneath the Barfüsser Church which was reserved as a burial site for wealthy families in 18th century Basel. However, until now, the cause of Bischoff’s death has always been ᴀssociated with the Sєxually transmitted disease, syphilis. But new research suggests this ᴀssumption is wrong.

The area where Anna Catharina Bischoff’s coffin was found (Adrian Michael / CC by SA 3.0)

Updating Historic Medical ᴀssumptions

In 1976, Anthropologist Bruno Kaufmann examined the mummy and identified the presence of Mercury sulphide in Bischoff’s lungs. While this chemical ultimately killed Bischoff, it had also prevented her mummy from decaying. Moreover, the atmospheric conditions inside the coffin and grave chamber slowed down microbial activity, which contributed to the preservation of the corpse. But because mercury inhalation therapy was a method of treating syphilis, 1970s medical historians “ᴀssumed” she had died off this disease that is ᴀssociated with Sєxual promiscuity.

Now, Microbiologist Mohamed Sarhan from Eurac Research says this initial diagnosis, that was based only on the presence of mercury in her lungs, was wrong. The DNA scientist told Daily Mail that his team of researchers have identified an “unknown pathogen” in Bischoff’s brain tissues containing genes found in a modern bacteria that cause bone lesions and pulmonary symptoms, normally ᴀssociated with syphilis, raising questions about Bischoff’s diagnosis and treatment.

Treatment with mercury vapour. In a small chamber, mercury vapour was inhaled. Illustration of the 17th century (public domain).

Identifying An Unknown Pathogen

The use of mercury as a treatment for syphilis was common in the past. However, the discovery of the previously unknown pathogen suggests that Bischoff’s illness may have been misdiagnosed. Mohamed Sarhan said the identification of the pathogen in Bischoff’s remains has “the potential to reveal new insights into the evolution and spread of diseases in the past” that might lead to “the development of new treatments and prevention strategies”.

Anna Catharina Bischoff’s mummified hand (CC)

Now that previous ᴀssertions regarding Boris Johnson’s sixth great-grandmother, Anna Catharina Bischoff, having died of syphilis, are out of the way, the facts relating to the woman’s life start to make sense. Bischoff’s father was a priest and after his death the family moved to Basel, where she married a priest and lived for more than 40 years. Considering she had seven children, four of whom survived to adulthood, the idea that her condition was caused by repeated Sєxual liaisons has always been contested, as her life seemed to be steeped in religion and family.