Ancient crypt offers clues about tuberculosis
After 265 mummified corpses are found, researchers unearth common lineage for disease
What tales can be told from the crypt? In the case of a Hungarian tomb, where 265 mummies were discovered two decades ago, it is the story of tuberculosis (TB), one of the oldest and most important human diseases.
Tuberculosis is caused by a bacterial infection that has long plagued the human race and traces of the disease can be found everywhere from Egypt’s mummies to Hippocrates’ book of epidemics. Today, it remains a leading infectious disease killer, even resurging in some areas where strains have grown increasingly resistant to drugs.
Scientists still disagree over the origins of human tuberculosis, however. While some believe the disease emerged within the last six millennia, others argue it dates back 70,000 years, when modern humans first migrated out of Africa.
But in a new study published in Nature Communications, international researchers have used a cutting-edge approach called metagenomics to unearth new clues — from inside a Hungarian crypt full of mummified corpses.
The crypt in Vac, a city 45 minutes north of Budapest, was unearthed in 1994 by workers renovating a Dominican church. They were stunned to discover forgotten stacks of ornately decorated coffins. Even more surprising were the 265 corpses inside, which had been naturally mummified thanks to the crypt’s favourable microclimate and wood chips inside the coffins that soaked up fluids, thus allowing the bodies to dry out.
Many of these people had also suffered from tuberculosis, making their preserved tissues a boon for scientists studying the disease. But this latest paper is the first to analyze the Vac mummies with metagenomics, a powerful tool that can sequence microbial genes directly in their habitats.
Looking at14 tuberculosis genomes found in the tissue samples of eight mummified corpses, the researchers discovered that multiple strains were circulating in Hungary in the 18th century when these people died.
They also found that the strains diverged from a common ancestor — and bear a striking resemblance to modern-day tuberculosis.
“All the historic genomes belonged to lineages that we see today,” said senior author Dr. Mark Pallen.
“So TB hasn’t changed much in 200 years . . . (and) it turns out that the most common ancestor of the EuroAmerican lineage that all our (tuberculosis) genomes belonged to dates back to late Roman times.”
According to the paper, this study is also the first to detect tuberculosis transmission between “long-dead” relatives, a woman named Anna Schoner, who died in 1793, and her daughter, Terezia Hausmann, who died four years later.
Pallen believes metagenomics can help researchers better understand not only historical tuberculosis but modern-day infections too. And while his study doesn’t prove the origins of tuberculosis — that will require more studies on even older samples — Pallen thinks it will be only a matter of time before scientists figure it out.
“We can expect more and more ancient TB genomes over the coming years as these techniques progress,” he said.
“And the matter will then be settled.”