Fingernail-sized round worms are a crisis in less economically developed countries, where they cause diarrhea, stunt children’s growth, and even kill. A new study suggests that these parasites were as common as they were in medieval Europe, suggesting the subsequent improvements in sanitation and hygiene in today’s Europe proved to be enough to win them over.
The “new study” is extensive and well done, says Roger Pricehard, a parasitologist at McGill University, who was not involved in the work. This confirms, he says, that the successful eradication efforts of Europe were not inherently the result of low parasite numbers.
The two most deadly roundworms – whipworms and hookworms – infect the intestines and excrete their eggs in feces, where they contaminate soil, crops, and water supplies. Currently more than 1.5 billion people are suffering.
These parasitic insects, known as a group known as helminths, have been parasitizing humans for thousands of years. Even in the remains of King Richard III, scientists have seen him in medieval bones and feces. Although the researchers knew that the parasites were there, they did not have a good way of estimating their prevalence.
In the new study, Adrian Smith, a zoologist and colleagues at the University of Oxford, embarked on an ambitious parasitic pilgrimage. The team collected approximately 600 soil samples from pelvic areas of skeletons buried in cemeteries between the seventh and 18th centuries in the Czech Republic, Germany and the United Kingdom. As a disintegration of a body, Smith explains, its intestines settle along the pelvic surface, making it a good place to hunt any parasitic eggs that had accompanied their host to the grave.
Researchers then analyzed DNA in samples that are today looking for genetic traits of the most common types of parasitic worms in many countries: Whipworms Thrissur Trikura, And belongs to the genus Hookworm Ascaris.
After examining the DNA of the samples, the scientists confirmed the presence of the parasitic egg by closely observing those samples under the microscope. Trichuris “Looks like an American football,” Smith explains, while Ascaris There is a round, lumpy orb. All told, the team found that about 25% of the individuals were infected Trichuris, And with about 40% Ascaris, And those rates remained fairly constant over time even in the 18th century.
Researchers have speculated about the same parasites in sub-Saharan Africa, Mexico, South America, East Asia and parts of other countries even today, researchers reported last week PLOS ignores tropical diseases.
Chemotherapeutic drugs developed in the 1960s may eradicate these insects, but medical records show that Europe was largely helminth-free in the early 20th century (although it drifted into the abyss of World War I). This suggests that Europe’s reforms for plumbing, sanitation and hygiene made the difference, Smith and his colleagues concluded. In addition, he reinforces the World Health Organization’s calls for reform in other groups as well as other countries. “These types of changes in Europe are very powerful.”