DNA from a 700-year-old mummy in Bolivia has revealed an unexpected chapter in the history of infectious disease. Researchers identified Streptococcus pyogenes, the bacterium responsible for strep throat and scarlet fever, in the remains of a young man who lived between 1283 and 1383. The finding shows group A strep was already present in South America before European arrival.
The skull came from the Bolivian highlands, where cold and dry conditions preserved both human tissue and ancient DNA. The remains are housed at the National Museum of Archaeology in La Paz and likely came from a chullpa, a traditional burial tower used across the Altiplano during the Late Intermediate Period, between the fall of Tiwanaku and the expansion of the Inca.
Scientists were studying microbial DNA preserved in mummified remains when they found traces of several bacteria inside a tooth. Streptococcus pyogenes stood out immediately because of its role in human illness. Researchers then reconstructed a near-complete genome from highly fragmented DNA, using a method designed for ancient material without depending on modern genetic references.
The reconstructed strain shares many similarities with modern group A strep. Genetic analysis showed the ancient bacterium carried many disease-related genes found in living strains today. The genome closely matches strains linked to throat infections, including strep throat and scarlet fever, rather than skin infections or more invasive diseases.
This marks the first confirmed detection of group A strep in ancient human remains. Despite the bacterium’s long history and global spread, researchers had never identified the pathogen in archaeological samples before now. Scarlet fever was once one of the leading causes of child death before antibiotics became widely available in the 1940s.
The genome also offers clues about the bacterium’s deeper history. Analysis suggests this Bolivian lineage separated from other known strains around 10,000 years ago. Researchers link this period to early human settlement in the Andes, when people entered new environments and came into contact with unfamiliar animals and ecosystems.
Bone analysis suggests the young man had lower-than-average nutritional health. At the same time, populations in the region were becoming denser and more mobile. These conditions often increase the spread of infectious disease and reduce resistance to infection.
To compare their results, the team reviewed older DNA datasets and found overlooked traces of Streptococcus pyogenes in 35 ancient individuals from Europe dating back about 4,000 years. They also identified a related Streptococcus species in 200-year-old gorilla remains from Africa.
The researchers still do not know whether this young man died from a strep-related illness. His remains do show the bacterium had already circulated among Indigenous communities in South America centuries before colonization.
The study adds a new piece to the history of a pathogen still affecting millions of people worldwide. Ancient DNA is now helping researchers trace diseases far beyond the limits of written history.
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