The whipworm (Trichuris trichiura) was once found all over the world, and it has infected people for thousands of years. It's also been identified in about 70 other species. The whipworm is now known as a parasite that can cause serious illness in areas where access to proper sanitation is difficult; the world's poorest areas are most at risk. The parasites are transmitted when water or food contaminated by infected feces is ingested. The parasitic worms can reach five to seven centimeters in length and can live undetected for several months in the intestines of healthy individuals, laying eggs the whole time. Those eggs are expelled in feces.
In the immunocompromised, whipworms can cause malnutrition, or various gastrointestinal diseases, and may delay childhood development. The whipworm can also trigger the immune system in humans and stimulate the microbiome.
Scientists have been able to use a microscope to detect parasitic eggs that were as many as 9,000 years old, said Professor Christian Kapel of the University of Copenhagen.
"Lucky for us, the eggs are designed to survive in soil for long periods of time. Under optimal conditions, even the parasite's genetic material can be preserved extremely well. And some of the oldest eggs that we’ve extracted some DNA from are 5,000 years old," added Kapel.
Now, researchers have analyzed one-thousand-year-old stool samples taken from latrines in several areas that were once used by Vikings, to learn more about the genetics of the whipworm. The DNA in the whipworm eggs was sequenced, and the results were compared to those from other studies to get a picture of how the whipworm has evolved over thousands of years.
"It has been quite surprising to fully map the genome of 1,000-year-old, well-preserved whipworm eggs in this new study," noted Kapel, who is corresponding study author. The findings have been reported in Nature Communications.
What was not surprising to the researchers was finding evidence that the whipworm moved with humans out of Africa about 55,000 years ago. This parallels the "so-called 'out of Africa' hypothesis on human migration," noted Kapel.
The researchers are hopeful that this new information will open up new treatment options for people who at risk of getting this parasitic infection. "Our mapping of the whipworm and its genetic development makes it easier to design more effective anti-worm drugs that can be used to prevent the spread of this parasite in the world's poorest regions," added Kapel.