The Stowaways

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A new study uncovered the genetic development of one of humanity’s oldest parasites, the BBC’s Science Focus wrote.

For thousands of years, the human whipworm, Trichuris trichiura, has been one of the main sources of bellyaches in ancient civilizations.

The parasites live in the intestines of their hosts and can grow up to 2.8 inches in length. Once inside, the worms lay their microscopic eggs that later exit the host’s body in the feces.

New hosts are then infected by drinking water or eating food that has been contaminated with the eggs.

Such a thing was quite common in the Middle Ages: A research team recently extracted fossilized whipworm eggs from fecal matter found in Viking settlements across Denmark.

Despite being more than a thousand years old, the DNA inside the eggs was very well-preserved. The team sequenced the genomes of the eggs and compared them to the ones of contemporary samples.

Their findings showed that whipworms have been plaguing humanity for tens of thousands of years.

“Unsurprisingly, we can see that the whipworm appears to have spread from Africa to the rest of the world along with humans about 55,000 years ago, following the so-called ‘out of Africa’ hypothesis on human migration,” said co-author Christian Kapel.

Kapel explained that the study could help in creating new drugs to treat whipworm infections and prevent the parasites from spreading in the future.

Although whipworms are rare in developed nations thanks to better sanitation, over 500 million people in the developing world are at risk of infection from them.