Why in news?
Scientists analysing a 700‑year‑old mummy from the Andean highlands of Bolivia have recovered DNA from Streptococcus pyogenes, the bacterium responsible for scarlet fever and strep throat. The discovery, reported in the journal Nature Microbiology, pushes back the timeline of known streptococcal infections in the Americas to well before European contact, indicating that these pathogens were already present and evolving locally.
Background
Scarlet fever is caused by group A Streptococcus bacteria that release a toxin leading to a distinctive red rash. The illness typically begins with a sore throat and fever, followed by a red rash that starts on the neck and spreads across the body. Other signs include a strawberry‑like tongue, flushed face and peeling skin. Most cases occur in children aged 5–15. Without treatment, complications such as ear infections, rheumatic fever and kidney inflammation can arise.
What did researchers find?
- Ancient DNA: Using sensitive sequencing techniques, the team extracted fragments of S. pyogenes DNA from the mummy’s lung tissue. Radiocarbon dating indicates the individual lived between 1283 and 1383, centuries before European colonisation.
- Throat‑specialist strain: Genetic analysis shows the ancient strain belongs to a lineage that primarily infects the throat, similar to modern strains causing pharyngitis and scarlet fever. It diverged from other lineages roughly 10,000 years ago, suggesting a long evolutionary history.
- Implications: The discovery means streptococcal diseases may have been widespread among Indigenous Americans long before Europeans arrived. It challenges earlier assumptions that Europeans introduced these infections to the New World.
Understanding scarlet fever
- Transmission: The bacteria spread through droplets from coughing and sneezing. Close contact in schools or crowded settings facilitates outbreaks.
- Symptoms: After an incubation period of 2–4 days, patients develop fever, sore throat and rash. The tongue often appears red and bumpy. The rash typically fades after a week, followed by peeling of the skin.
- Treatment: Antibiotics such as penicillin effectively clear the infection and prevent complications. Early treatment reduces the risk of rheumatic fever and kidney problems.
- Public health: Although scarlet fever was a major killer in the 19th century, its incidence declined with antibiotics and improved hygiene. Recent resurgences in some countries highlight the need for continued surveillance.
Sources: Live Science
