Researchers identified the pathogen’s genetic material while examining a tooth from a naturally mummified skull housed at MUNARQ – the National Museum of Archaeology in La Paz. Using a method that reassembles previously unknown genomes from numerous short DNA fragments, they reconstructed a nearly complete, ancient genome of Streptococcus pyogenes.

The reconstructed genome shows clear similarities to modern strains of the globally widespread bacterium, which can cause a variety of illnesses ranging from harmless throat infections to scarlet fever and life-threatening toxic shock syndrome.

Despite the pathogen’s great medical significance: scarlet fever was historically one of the leading causes of death among children, little is known about its evolutionary history. This finding now shows that the bacterium was already circulating among indigenous populations in South America before European colonization: the young man from whom the tooth originated lived between 1283 and 1383 AD.

The study was made possible by a cooperation agreement between Eurac Research and the Bolivian Ministry of Cultures and has been published in Nature Communications.