Researchers found evidence of a parasite called Giardia duodenalis in the sediment below two ancient toilets, according to a new paper published in the journal Parasitology.
G. duodenalis is one of several pathogens that can cause dysentery. Previous research had identified G. duodenalis in Turkey during the Roman period, as well as in Israel during the medieval and Ottoman periods. But this new discovery in Jerusalem represents the earliest known evidence of the parasite, according to the researchers.
The findings—coupled with descriptions in historical texts—suggest dysentery was common in the Kingdom of Judah during the seventh and early sixth centuries B.C.E. One text reads: “If a person eats bread and drinks beer and subsequently his stomach is colicky, he has cramps and has a flowing of the bowels, setu has gotten him,” per a statement from the researchers.
“These early written sources do not provide causes of diarrhea, but they encourage us to apply modern techniques to investigate which pathogens might have been involved,” says lead author Piers Mitchell, an archaeologist at the University of Cambridge, in the statement. “We know for sure that [G. duodenalis] was one of those infections responsible.”
At this point in history, Jerusalem likely had between 8,000 and 25,000 residents, but no sewage system or flushing toilets, per CNN’s Katie Hunt. Only wealthy elites had toilets, which typically consisted of a hole carved into a slab of stone with a latrine cesspit below for storing the waste. Additionally, people did not yet understand the relationship between feces and disease.
“The limited sanitation technologies available at the time, the shortage of fresh water for much of the year, the population density of these towns and widespread house flies all had the potential to contribute to infection,” write the researchers in the paper.
Archaeologists uncovered one of the toilets used in the study during the 2019-20 excavation season at Armon ha-Natziv in south Jerusalem. The toilet was part of an elaborate estate that dates to around the mid-seventh century B.C.E.
They found the other toilet at the House of Ahiel, a large home with seven rooms that dates to around the eighth century B.C.E.
As Mitchell tells i24NEWS’ David Matlin, such research “helps us understand how people first started to live and problems they had.”
Previous studies of the sediment below the toilets found the eggs of several intestinal parasites: tapeworm, pinworm, roundworm and whipworm. But identifying the tiny single-celled organisms that can cause dysentery proved more challenging, as they are fragile and difficult to detect using standard methods.
In this case, researchers used a biomolecular technique that can detect single-celled organisms. In addition to G. duodenalis, they also tested the sediment samples for Entamoeba histolytica and Cryptosporidium—other kinds of microorganisms that can cause dysentery—but didn’t find them.
G. duodenalis is still present today and can cause diarrheal infections in humans and animals, according to the Centers for Disease Control and Prevention. It can spread from person to person, or via contaminated objects, foods, surfaces and water. People typically become infected with G. duodenalis after swallowing contaminated water from swimming pools, rivers and lakes, as well as drinking water.
Other analyses of feces have also led to new historical insights: Scientists now know that medieval monks were susceptible to intestinal worms, that the people who built Stonehenge likely ate undercooked animal organs and that a hunter-gatherer living in North America some 1,500 years ago ate a rattlesnake whole.