(CN) — Eggs from parasitic worm infestations in human intestines throughout history are readily detectable in archaeological deposits in places where intestinal parasites are no longer considered endemic, including the United Kingdom, and researchers are using them for clues into past sanitary and dietary practices.
Although the disappearance of intestinal parasitic worms in the U.K., Europe and other developed countries is likely due to changes in sanitation and food preparation over time, specific reasons for why such infestations are no longer endemic in these areas are still not well understood, according to a study published Thursday in the journal PLoS Neglected Tropical Diseases.
Researchers from the biology and archaeology departments at the University of Oxford searched burial sites from the prehistoric to early Victorian periods looking for evidence of parasitic worm infestations. They examined soil samples from the abdominal region of 464 individual skeletal remains from 17 burial sites for evidence of parasitic eggs, which do not easily break down into soil.
They found that two out of three sites that were studied showed almost no evidence of infestation during the industrial period. Evidence from a third site inside the city of London showed a continued level of high infestation during this period.
Eggs from two worm species that enter the human body through exposure to fecal matter – roundworms and whipworms –were identified, along with tapeworms, which people can get by eating contaminated or undercooked food. Only the first type was found in high frequency.
Researchers believe that local changes in sanitation and hygiene may have reduced infection in some areas before nationwide changes during the Victorian-era "sanitary revolution."
While parasitic worms are no longer a major concern in modern Britain, such infestations cause many health problems in poor countries, particularly in subtropical climates.
“Defining the patterns of infection with intestinal worms can help us to understand the health, diet and habits of past populations. More than that, defining the factors that led to changes in infection levels (without modern drugs) can provide support for approaches to control these infections in modern populations,” co-lead authors Hannah Ryan and Patrik Flammer said in a statement.
The study found that people in the Roman and the Late Medieval period fared the worst, with the highest rates of worm infection. Their infection rates were similar to those seen in the most affected regions today.
The rates of infestation of parasites transmitted through feces would have been reduced by large-scale municipal improvements to sewage and water treatment, the paper concludes, including a decline in use of night soil to fertilize crops.
Additionally, cholera outbreaks between 1831 and 1866 alongside endemic Typhoid, which have been linked to contaminated drinking water, were a key driver of sanitation reform that involved infrastructural improvement, legislation and promotion of municipal responsibility.
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