Like humans, parasites and infectious diseases have favored the Silk Road to spread throughout the world. The first formal proof has been provided.
The Silk Road would have been the royal road for infectious and parasitic diseases. This thesis is confirmed for the first time. In support of this: millennial sticks still soiled with feces. The method is unconventional, since it combines archeology and scientific analysis, but conclusive. Various diseases have been transmitted along this trade route by the men and women who have taken it. This is the conclusion of a team from the University of Cambridge (United Kingdom), which publishes in the Journal of Archaeological Science: Reports.
A popular route
The Silk Road flourished during the Han Dynasty in China (202 BC to 220 AD). In France, the stories of Marco Polo popularized this trade route, widely used for millennia. Indeed, it rallies the area of the eastern Mediterranean to the borders of eastern Asia. Soldiers, merchants and dignitaries have traveled these long kilometers for centuries. At their side, various bacteria, viruses and parasites. In any case, this is what researchers have repeatedly assumed, observing strong similarities between strains of bubonic plague, anthrax and leprosy between the two continents.
Only one key element was missing: formal evidence. “Until now, there was no evidence showing that the Silk Road is responsible for the spread of infectious diseases, explains Piers Mitchell, who signs this study. They could have spread from China to Europe through India, to the south, or Mongolia and Russia, to the south. “
Source : Jori Avlis/ Flickr
Parasite eggs
The proof came from an unusual place: latrines. These places of ease are located within a major relay along the Silk Road, east of the Tarim basin which borders the Taklamakan desert. The relay Xuanquanzhi would have been founded under the Han dynasty, in 111 before our era, and used until 109 AD Archaeologists have excavated several “hygienic sticks”, summary ancestors of our toilet paper. These pieces of wood are intended to remove fecal matter from the anus, using a cloth rolled up at one end. A few pieces of fabric, still soiled despite the centuries, were taken.
“When I first observed Chinese fluke eggs under my microscope, I realized that we had made a great discovery,” recalls Hui-Yuan Yeh, co-signer of the study. And for good reason: in addition to feces, parasitic worm eggs are always present on the hygienic sticks. Four species, more precisely: ascaris (Ascaris lumbricoides), whipworm (Trichuris trichiura), tapeworm (or tapeworm, Taenia sp.) and Chinese fluke (Clonorchis sinensis). It is this last worm that provides the proof that was so lacking.
1,500 km of wandering
Chinese fluke causes abdominal pain, diarrhea, jaundice and ultimately liver cancer. This parasite needs, in order to develop, spaces where water is abundant, even marshy. The relay of Xuanquanzhi, located in an arid and almost desert zone, does not in any way meet these requirements. In fact, you have to travel 1,500 km west to find a location more conducive to its development, around the city of Dunhuang.
“Finding traces of these species in a latrine indicates that a traveler went there from a region of China where water is abundant, and where the parasite was endemic,” summarizes Hui-Yuan Yeh. Throughout this time, the traveler in question retained the parasite. The same phenomenon was undoubtedly observed with infectious diseases. For Piers Mitchell, who summarizes this work on the site The Conversation, “This makes the idea that bubonic plague, leprosy and anthrax were spread along the Silk Road more likely. “
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