The mysterious ailment of the merchants of the Silk Road
One of the most captivating and exotic travel stories in all of history is the ‘Book of wonders‘, from the Venetian Marco Polo (1254-1324). It was written at a time when the American continent had not yet been discovered and when Europeans still lived in the fog of the Middle Ages.
The Italian adventurer and merchant left us a fabulous and exquisite account of his journey through the Silk Road, a term that at that time had not yet been coined. It would make its appearance in 1877 from the pen of the German geographer Ferdinand Baron von Richthofen, with him he referred to a set of trade routes – almost ten thousand kilometers long – that were established between Asia and Europe and whose starting point was in the ancient Chinese city of Chang’an (present-day Xian).
From there the merchants crossed Central Asia, reached Samarkand and, taking the Persian Royal Road, accessed modern-day Lebanon and Turkey, from where they would make their final journey to Europe.
Cultural and biological engine
Merchants, hermits, soldiers, pilgrims and nomads traveled tirelessly on this route. Its name refers to silk, one of the most valuable products that traveled in the long caravans of camels, but so did bronze, ceramics, spices, porcelain, skins, jade or lacquer. Meanwhile, but in the opposite direction, other products such as ivory, silver, dyes or glass circulated.
In this way, the Silk Road became for more than two thousand years a cultural, religious, commercial and… biological exchange. And it is that this route also had its reverse since it allowed the exchange of diseases and genetic material between the two continents. In this microbiological exchange we find, for example, bacilo de Hansen, the Yersinia pestis or the Bacillus anthracis.
As for the genetic transaction, it is reflected in a pathology known as Behcet’s disease. It is a rare, potentially dangerous entity whose main symptoms are localized ulcers in the mouth and genitals, as well as inflammation at the ocular level. The name of the ailment refers to the Turkish dermatologist Hulusi Behcet (1889-1948), who first described it in 1937.
In 2002, after an exhaustive review, it was proposed internationally to change its name to Adamantiades-Bechcet, to pay tribute to the Greek ophthalmologist Benediktos Adamantiades (1875-1962), who practiced his specialty in the former Ottoman Empire and who came to diagnose the first patients with this disease in 1930 – seven years before Dr. Behcet.
A disease of autoimmune origin
The Behcet’s disease o la silk road disease It is an elusive pathology that is difficult to diagnose, which manifests itself in outbreaks and in which the immune system attacks the organism itself, it could be said that it ceases to be an ally to become an enemy to fight.
Worldwide, patients with this pathology are located mainly along the Silk Road, so that we can get an idea of the importance, one piece of information goes ahead: there is a prevalence of 370 affected per 100,000 inhabitants, compared to the 5-10 that are counted in the rest of the world.
And it is that, quite possibly, the current patients who live in that geographical area are the descendants of those merchants who traveled along the trade route for centuries and who carried evil in their genes.
The susceptibility to suffer from this disease is located in genes located in a very specific region of the genome, so that the risk is greater for those people who have the HLA B51 antigen. Recently, other genes directly related to the disease have been discovered: ERAP1, CCR1, KLRC4 and STAT4.
These findings are fundamental advances in our understanding of Silk Road disease and its connection to other diseases, a decisive step in the search for effective therapies.
Pedro Gargantilla is an internist at the Hospital de El Escorial (Madrid) and the author of several popular books.