JAN 10, 2016 1:19 PM PST

Iceman Reveals Pathogen's Migration

WRITTEN BY: Kerry Evans
An international team of researchers recently confirmed that Ötzi the “Iceman” harbored a unique strain of Helicobacter pylori in his stomach.

Ötzi (pronounced “etsie”) was discovered in 1991 in a glacier in the Ötzal Alps near the Italian-Austrian border.  Ötzi lived about 5,300 years ago during the Copper Age, a time when metal tools and weapons became widespread.  His fully-sequenced genome revealed that he had brown eyes and was lactose-intolerant.  At the time of his death (from an arrow to the shoulder) Ötzi was about 45 years old.
 
Ötzi lived about 5,300 years ago.

Since his discovery, Ötzi has become one of the most thoroughly studied mummies in the world.  Until now, however, researchers weren’t sure if Ötzi, likely nearly half of all modern humans, was infected by Helicobacter pylori in his stomach.  H. pylori is a spiral-shaped bacterium that burrows into the stomach’s mucus layer to avoid being killed by stomach acid.  Today, about one tenth of people infected with H. pylori develop symptoms such as gastritis and stomach ulcers, and it may play a role in stomach cancer.
 
H. pylori burrows into the stomach mucosa.

According to paleopathologist Albert Zink, “evidence for the presence of the bacterium Helicobacter pylori is found in the stomach tissue of patients today, so we thought it was extremely unlikely that we would find anything because Ötzi's stomach mucosa is no longer there”.  Despite this, the group extracted DNA from Ötzi’s stomach contents and looked for H. pylori DNA.  “We were able to tease out the individual Helicobacter sequences and reconstruct a 5,300 year old Helicobacter pylori genome”, says Zink.
Ötzi, reconstructed.
The group predicted that there were two strains of H. pylori that infected early humans, one from Africa and one from Asia.  A European strain eventually arose - a hybrid of the African and Asian strains - but scientists don’t know exactly when this happened.  "We had assumed that we would find the same strain of Helicobacter in Ötzi as is found in Europeans today … it turned out to be a strain that is mainly observed in Central and South Asia today”, says Thomas Rattei, a computational biologist at the University of Vienna.

According to microbiologist Frank Maixner, “the recombination of the two types of Helicobacter may have only occurred at some point after Ötzi's era, and this shows that the history of settlements in Europe is much more complex than previously assumed”.
 

Sources: National Geographic, Science Daily, Wikipedia
 
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
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