Ancient Bolivian Mummy Reveals Scarlet Fever's Centuries-Old Origins

Genetic analysis of a 500-year-old mummy's tooth uncovers evidence of virulent streptococcal strains in pre-Columbian South America.

Apr. 20, 2026 at 3:23am

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A bold, abstract painting in earthy tones depicting the complex genetic structure and global dispersal of Streptococcus pyogenes, the bacterium that causes scarlet fever, conveying the ancient origins of this virulent pathogen.Genetic analysis of a 500-year-old Bolivian mummy's tooth reveals the deep evolutionary history of the scarlet fever-causing bacterium, challenging assumptions about the disease's origins.Houston Today

Researchers have made a breakthrough in the medical history of scarlet fever by analyzing the dental pulp of a 500-year-old Bolivian mummy. Genetic sequencing revealed the presence of virulence genes associated with the disease, challenging long-held assumptions that scarlet fever emerged only after European contact. This discovery suggests that strains of Streptococcus pyogenes capable of causing severe scarlet fever were already circulating in the Andes centuries before colonization.

Why it matters

This finding reshapes our understanding of the global trajectory of Streptococcus pyogenes, the bacterium that causes scarlet fever. It suggests the pathogen had a far more complex history of evolution and dispersal than previously thought, with virulent strains potentially existing in isolated populations long before the Columbian Exchange. This has important implications for epidemiological models, vaccine development, and clinical preparedness for emerging streptococcal threats.

The details

The study, led by researchers at the University of Zurich and funded by the Swiss National Science Foundation, analyzed dental pulp from a naturally mummified child estimated to be 8-10 years old at the time of death. The sample was recovered from the high-altitude Chiribaya archaeological site in southern Peru, near the Bolivian border. Genetic analysis revealed the presence of speA and speC superantigen genes, which are directly responsible for the characteristic rash and systemic inflammation of scarlet fever. This indicates the pathogen possessed full virulence potential, not just the ability to cause mild pharyngitis.

  • The mummy is estimated to be around 500 years old, predating significant European contact in the region.
  • The study was published in Nature Communications in 2026.

The players

Dr. Cristina Sánchez-Ramírez

Lead paleopathologist at the University of Zurich's Institute of Evolutionary Medicine.

Dr. James Musser

Chair of Pathology and Genomic Medicine at Houston Methodist Hospital and a leading authority on Streptococcus pyogenes evolution.

Instituto Nacional de Arqueología (INAR)

Bolivian institution that collaborated on the research.

Ministerio de Cultura

Peruvian institution that provided ethical oversight for the research.

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What they’re saying

“Finding intact virulence genes in this context forces us to reconsider the idea that scarlet fever was a 'new' disease of colonial contact. Instead, we may be seeing the tip of an iceberg—ancient, geographically diverse lineages of S. Pyogenes that caused episodic outbreaks long before globalization.”

— Dr. Cristina Sánchez-Ramírez, Lead paleopathologist at the University of Zurich's Institute of Evolutionary Medicine

“This ancient DNA evidence doesn't just add a footnote to history—it recalibrates our molecular clock. If virulent strains were circulating in isolation 500 years ago, then the global diversity of S. Pyogenes is far older and more structured than we thought. That has implications for vaccine design, as we must target conserved virulence mechanisms, not just transient epitopes.”

— Dr. James Musser, Chair of Pathology and Genomic Medicine at Houston Methodist Hospital

What’s next

The research team plans to analyze additional dental samples from pre-Columbian burial sites across the Andes to map the geographic distribution of ancient virulent strains, which could inform global GAS vaccine strategies targeting conserved superantigens.

The takeaway

This discovery of virulent Streptococcus pyogenes strains in a 500-year-old Bolivian mummy challenges long-held assumptions about the origins of scarlet fever. It suggests the disease had a far more complex global history, with implications for understanding pathogen evolution, improving diagnostic practices, and developing more effective vaccines.