Boris Johnson's ancestor did not have syphilis, new scans show

Anna Catharina Bischoff
Anna Catharina Bischoff

An 18th century mummified noblewoman related to Boris Johnson has had her reputation restored after scientists discovered she did not die with syphilis.

The body of Anna Catharina Bischoff - the great-great-great-great-great-great-great grandmother of the former prime minister - was uncovered in Switzerland in 1975 during renovations on Basel’s Barfusser Church.

After her death in 1787, her corpse was preserved in a mummified state because she had taken mercury before her death, which experts have assumed was to treat syphilis, the sexually transmitted disease.

But new scans of her body have shown high levels of an unknown bacterial species in the brain tissue samples, suggesting that was the actual cause of death.

The bacterium is from the same family that causes leprosy and tuberculosis, but the type discovered is more closely related to bacteria found in water sources and soil, rarely infecting humans.

The team said they could not detect any molecular signs of syphilis bacteria in the scans.

Possible misdiagnosis

Researchers believe that Anna Catharina may have been misdiagnosed with syphilis and treated with mercury, with lethal results.

“Mercury was already widely used for treating skin diseases in Arabic medicine, and then was brought to Europe to treat infections in general, including syphilis,” said Dr Mohamed Sarham, of the Institute for Mummy Studies at Eurac Research in Bolzana, Italy.

“It was used back then as pills and ointment, and also as vapour for inhalation. Mercury in general is poisonous to humans regardless of the health status of the treated person. It does not have an immediate poisoning effect but rather with the long-term exposure and accumulation in the body, in addition to the affected organ.”

mummy Boris Johnson
mummy Boris Johnson

Known as ‘Switzerland’s most famous mummy’, Anna Catharina was buried in front of the church altar, and found wearing expensive clothes, with no signs of malnutrition, suggesting she had been wealthy.

Although there were no markers, there were rumours she was linked to the Bischoff family so researchers extracted DNA from the mummy’s big toe and compared it with genetic material from a modern relative.

Not only was it a match, showing that the woman must have been a Bischoff, but further archival research showed she was Anna Catharina Bischoff, who died in 1787, a direct maternal ancestor of Mr Johnson.

She married a church minister and spent most of her adult life living in Strasbourg.

Marie Luise von Pfeffel, her great-great-grandaughter, married Stanley Fred Williams and their daughter Irene, who Boris always referred to as "Granny Butter", wed his grandfather Wilfred Kemal.

The couple changed their name from Kemal to Johnson amid growing tensions with Turkey. Mr Johnson’s full name is Alexander Boris de Pfeffel Johnson.

The research was published in the journal BMC Biology.