Mummified bodies show TB's impact on 18th-century Europe
The naturally mummified bodies, discovered in a 200-year-old Hungarian crypt in the Dominican church of Vac, have 14 TB genomes. The presence of these genomes suggests that Europe had mixed infections when TB was at its highest rates.
The team used metagenomics to find the TB DNA in the mummies. This method directly sequences DNA from samples with the risk of deliberately fishing out TB DNA or growing bacteria on the samples. This analysis was so detailed that the scientists linked TB DNA strains from a middle-aged mother and her grown-up daughter, suggesting the two died from the same infection.
"Microbiological analyses of samples from contemporary TB patients usually report a single strain of tuberculosis per patient,” study author Mark Pallen from the Warwick Medical School said. “By contrast, five of the eight bodies in our study yielded more than one type of tuberculosis -- remarkably from one individual we obtained evidence of three distinct strains."
The sequences helped the researchers to date the lineage of the TB strain to the late Roman Empire. This supports the recent but controversial theory that all TB strains have a common ancestor from as recently as 1,000 years ago.
“By showing that historical strains can be accurately mapped to contemporary lineages, we have ruled out, for early modern Europe, the kind of scenario recently proposed for the Americas -- that is wholesale replacement of one major lineage by another -- and have confirmed the genotypic continuity of an infection that has ravaged the heart of Europe since prehistoric times,” Pallen said. "We have shown that metagenomic approaches can document past infections. However, we have also recently shown that metagenomics can identify and characterize pathogens in contemporary samples, so such approaches might soon also inform current and future infectious disease diagnosis and control."
More details are available in the article that was published in Nature Communications.