700-year-old Bolivian mummies contain evidence of strep throat, the earliest known disease in the Americas

Researchers used ancient DNA analysis to identify the presence of Streptococcus pyogenes (group A streptococcus) in a 700-year-old Bolivian mummy, confirming that streptococcal infections existed in the Americas before European exploration. The strain of streptococcus found in the mummy is similar to modern strains of streptococcus that cause strep throat and scarlet fever.

Researchers say this is the first time group A streptococcus has been identified at an archaeological site.

“We were not specifically looking for this pathogen,” Frank Meixner, director of Italy’s Eulac Mummy Research Institute and co-author of the study published April 13 in Nature Communications, said in a statement. “When performing genetic analysis on mummies, we approach the work with an open mind and analyze not only human genetic material, but also the DNA of the numerous microorganisms present in human remains.”

you may like

Meixner and his colleagues were studying naturally mummified bodies found in chulpas, a type of ancient funerary tower in the Andean highlands of Bolivia. These people were buried during the Late Intermediate Period (1000-1450), after the collapse of the Pre-Inca civilization known as Tiwanaku and before the rise of the Inca Empire.

When researchers analyzed one particular mummy – a young adult man with an altered skull who lived between 1283 and 1383 – they found DNA from several types of bacteria that can cause botulism, including Streptococcus pyogenes and Clostridium botulism.

“Detection of Streptococcus pyogenes was particularly important,” the researchers wrote in the study. “Despite the presence of this pathogen in modern epidemics, it has not yet been detected in ancient times.”

Group A streptococci are now found around the world and cause a variety of illnesses, ranging from mild symptoms like strep throat to life-threatening infections like necrotizing fasciitis. This bacterium also causes scarlet fever. The disease was historically one of the leading causes of childhood death until antibiotics were developed in the 1940s.

Although streptococci have been prevalent around the world for centuries, information about the evolution of this bacterium is only available from modern strains, leaving open questions about whether streptococci were present in the Americas before European colonization.

However, in a new study, researchers were able to isolate the nearly complete genome of Streptococcus pyogenes from one tooth of a Bolivian mummy. The 700-year-old genome is the oldest known presence of this bacterium in the Americas, the researchers wrote.

DNA analysis also revealed that the ancient Bolivian Streptococcus strain diverged from all other Streptococcus pyogenes lineages about 10,000 years ago. The researchers noted in their paper that this period may have coincided with the first human invasion of the Andes, as humans encountered an unknown animal that may have carried the pathogen.

However, it is still unclear which diseases caused by group A streptococci were present in pre-Hispanic Bolivia. The genome the researchers identified most closely resembles modern “throat specialist” strains, strains that cause strep throat and scarlet fever rather than skin diseases such as impetigo or “flesh-eating disease.” These streptococcal strains also increase in prevalence during the cool season, which is consistent with the cold and dry climate of the Bolivian highlands.

The young man, whose skeleton tested positive for streptococcal DNA, lived in a society with increasing population density and high migration rates, and researchers found that his bones likely showed a below-average nutritional status. All of this evidence “could influence immune function and susceptibility to such ancient infections and past potential epidemics,” the researchers wrote, but they cannot confirm exactly how the man died.

Evidence from a new strain of streptococcus in Bolivia is consistent with the pathogen’s origins in the United States, the researchers wrote. However, as this is the first time group A Streptococcus has been identified in an ancient site, the researchers noted that additional studies including a broader dataset of ancient and modern Streptococcus pyogenes genomes from Europe, Africa, Asia, and the Americas are desperately needed. Accumulating that information could help experts unravel the evolutionary history of streptococcus and its impact on life and death in ancient humans.

First Americans Quiz: How much do you know about the first people to reach the Americas?