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DNA in Viking’s poo sheds new light on 55,000-year-old relationship between gut mates – Reuters

Summary: Stool samples taken from the Viking latrines allowed researchers to map the genome of the Whipworm parasite. The study maps the global spread of the parasite and its relationship to humans.

Source: University of Copenhagen

Using stool samples from Viking latrines, researchers at the University of Copenhagen have genetically mapped one of the oldest human parasites – the whipworm. The mapping reflects the parasite’s global spread and its interaction with humans, a delicate relationship that can make us healthier and sicker.

Using fossilized eggs in feces dating back 2,500 years from Viking settlements in Denmark and other countries, researchers from the Department of Plant and Environmental Sciences at the University of Copenhagen and the Wellcome Sanger Institute (UK ) performed the largest and most thorough genetic analysis of one of the oldest parasites found in humans – the whipworm.

The study, published in Nature Communication, presents completely new knowledge on the development and prehistoric dispersion of the parasite. This knowledge can be applied in efforts to prevent parasite drug resistance and its future spread.

The study suggests that humans and the parasite have developed a delicate interaction over thousands of years, whereby the parasite tries to stay ‘under the radar’ so as not to be pushed back, giving it more time to infect. new people. From other studies, whipworm is known to stimulate the human immune system and gut microbiome, to the mutual benefit of host and parasite.

While whipworm (Trichuris trichiura) is now rare in industrialized countries, and most often causes only minor problems in healthy individuals, the parasite is estimated to affect 500 million people in developing countries.

“In people who are malnourished or have a weakened immune system, whipworm can lead to serious illness. Our mapping of whipworm and its genetic development facilitates the design of more effective anti-worm drugs that can be used to prevent the spread of this parasite in poorer regions of the world,” says Professor Christian Kapel of the Department of Plant Sciences and environmental studies of the UCPH. .

Fossilized latrine poo from Copenhagen and Viborg

The eggs, not the worms, allowed the researchers to examine the genetic material of whipworms thousands of years old. Due to the extremely durable chitin in the egg capsules, their internal DNA was well preserved while the eggs were buried in moist soil.

Examining samples of fossilized feces that had previously been discovered in the latrines of the Viking colonies of Viborg and Copenhagen, the researchers isolated the eggs under a microscope, sieved them from the feces and subjected them to elaborate genetic analyzes that the researchers have been perfecting for years in previous studies.

“We have known for a long time that we can detect parasite eggs up to 9,000 years old under a microscope. Luckily for us, eggs are designed to survive in the ground for long periods of time. Under optimal conditions, even the genetic material of the parasite can be extremely well preserved. And some of the oldest eggs we’ve extracted DNA from are 5,000 years old. It was quite surprising to fully map the genome of well-preserved 1000-year-old whipworm eggs in this new study,” says Christian Kapel.

The researchers examined archaeological stool samples from several locations. These ancient genetic samples are compared with contemporary samples obtained from people with whipworm around the world. This provided researchers with insight into the worm’s genome and how it evolved over tens of thousands of years.

The study, published in Nature Communications, presents completely new insights into the development and prehistoric dispersal of the parasite. This knowledge can be applied in efforts to prevent parasite drug resistance and its future spread. Credit: University of Copenhagen

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

Can live undetected in the gut for months

A whipworm can reach five to seven centimeters in length and live unnoticed in the intestine of a healthy individual for several months. During this time, he continuously lays eggs, which are expelled through feces. In people with weakened immune systems, whipworm can cause a wide range of gastrointestinal illnesses, malnutrition, and even stunted child development.

Worms are transmitted by the fecal-oral route, which means that microscopic parasite eggs in soil can spread to drinking water or food, after which they are ingested through the mouth of a new host.

“The eggs lie in the ground and develop for about three months. Once matured, the eggs can survive even longer in the wild, as they wait to be consumed by a new host in whose digestive tract they will hatch. Their entire life cycle is adapted to survive in the ground for as long as possible,” explains Christian Kapel.

So, the heyday of these worms in our part of the world was when our toilet and kitchen conditions, as well as our personal hygiene, were very different from those of today.

“In Viking times and up until the Middle Ages, we didn’t have very sanitary conditions or well-separated kitchen and toilet facilities. This allowed the whipworm much better opportunities to spread. Today it is very rare in the industrialized part of the world. Unfortunately, favorable conditions for the spread still exist in less developed regions of the world,” says Christian Kapel.

Funding: The study is led by the University of Copenhagen’s Department of Plant and Environmental Sciences, Section of Organismal Biology and carried out in collaboration with the Wellcome Sanger Institute (UK).

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About this development research news

Author: Michael Jensen
Source: University of Copenhagen
Contact: Michael Jensen – University of Copenhagen
Image: Image is credited to University of Copenhagen

Original research: Free access.
“Genomics of ancient and modern Trichuris trichiura populations” by Christian Kapel et al. Nature Communication


Genomics of ancient and modern Trichuris trichiura populations

Trichuriasis, a neglected tropical disease, is caused by whipworm Trichuris trichiuraa soil-transmitted helminth that has infected humans for millennia.

Today, T.trichiura infects up to 500 million people, mostly in communities with poor sanitation infrastructure allowing sustained faecal-oral transmission.

Using whole genome sequencing of geographically distributed worms collected from human and other primate hosts, as well as ancient samples preserved in latrines and archaeologically defined deposits dating back less than a thousand years, we present the first population genomic study of T.trichiura.

We describe the continent-wide genetic structure between whipworms infecting humans and baboons versus those infecting other primates. Demographic analyzes of admixtures and populations support a stepwise distribution of genetic variation that is highest in Uganda, consistent with an African origin and later translocation with human migration.

Finally, genome-wide analyzes between human samples and between human and non-human primate samples reveal local regions of genetic differentiation between geographically distinct populations.

These data provide insight into zoonotic reservoirs of infectious viruses for humans. T.trichiura and support future efforts towards implementing genomic epidemiology of this globally important helminth.

DNA in Viking’s poo sheds new light on 55,000-year-old relationship between gut mates – Reuters

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