A brutal health trend from the 19th century brought these animals close to extinction

In the 19th century, the European medicinal leech, Hirudo medicinalis, faced a significant decline due to overexploitation, habitat destruction, and loss of food sources. This decline was largely driven by the leech's popularity in medicine, particularly during the Victorian era when it was used to treat a wide range of diseases including cancer, tuberculosis, and mental illness.

The leech's popularity reached new heights, thanks in part to the influence of Francois-Joseph-Victor Broussais, a prominent physician in Paris. Broussais declared that all ills were the result of inflammation, and bleeding was the cure, leading to the widespread use of leeches in medicine. As a result, thousands of European medicinal leeches were transported by travel companions, and some hospitals, such as Broussais's, used over two million leeches from 1830 to 1836. Physicians often prescribed dozens of leeches for a single treatment session, and in gastritis therapy, as many as 20 to 40 leeches could be prescribed.

However, the leech's popularity led to its scarcity across Europe. Repeated blood meals posed risks to leech collectors, including infections and transmissible diseases. By the early 1900s, the European medicinal leech became endangered in many locations throughout Europe. In response, some European governments implemented early wildlife protection measures, such as banning leech exports or regulating leech collecting.

Despite the declining population, the European medicinal leech continues to play a role in modern medicine, particularly for transplants and plastic surgery. Today, it is often bred in laboratories to meet the demand. The leech's popularity in the past can be attributed to its gentle touch and voracious appetite.

Looking back, it's clear that the European medicinal leech faced significant challenges in the 19th century. However, through conservation efforts and advancements in medicine, this unique creature continues to play a vital role in healthcare today. The European medicinal leech is now considered near threatened by the International Union for Conservation of Nature (IUCN), highlighting the importance of continued efforts to protect this fascinating species.