After spending much of the 20th century relegated to the dustbin of quack medicine, leeches are now enjoying a renaissance in the doctor's office. But although there's solid evidence showing the bloodsuckers can have plenty of benefits, I can't help but raise an sceptical eye at one of the claims highlighted in a video report released by Reuters this week - namely that they can ramp up athletes' healing like some sort of reverse Wolverine.
Artur Klena, identified as the laboratory head of a Polish leech exporting firm, told Reuters that among other things, sports clubs are buying up leeches to help their jocks "regenerate muscles after intensive exercise."
Leeches have been used for thousands of years to treat a variety of medical conditions, including pain, gout, fever, and hearing loss. For most of that time, leeches were revered simply because they sucked blood out from us — the leading theory being that sickness was caused by an imbalance of "humours." Our leechmania got so big, we were nearly on the verge of wiping out certain species we used by the early 19th century, such as Hirudo medicinalis. But as the era of modern medicine began rolling along, leeches faded out of relevance.
More recently, however, doctors and researchers have found that leeches - and the cocktail of chemicals found inside their saliva that aid their dine-and-dash routine - really can have useful effects on the body. Their saliva contains powerful blood-thinners and anti-inflammatory chemicals that have been used to develop treatments for cardiovascular disease, while the leeches themselves can clean up some gaping wounds better than other modern methods we have available. Other research has found evidence that components in leech saliva could possibly even treat cancer pain or tackle conditions like arthritis.
That said, while the Food and Drug Administration did formally approve leech therapy in 2004, it was only for a strict purpose.
"[T]hey are cleared for use by doctors for a very specific reason: removing stagnant, deoxygenated blood that has pooled abnormally into an area and must be sucked out in order to decrease the pressure and allow fresh blood to enter the area in its place," Ronald Sherman, a physician at the Orange County Health Care Agency in California, as well as director of the BioTherapeutics, Education & Research (BTER) Foundation, told Gizmodo via email.
"Many people use leeches for other purposes, too ... but they are generally not doctors or hospitals, whose licence could be revoked for using leeches for non-approved uses. What's more, if they are using them for non-approved purposes, they are not likely to admit it publicly," he added.
Though Sherman doesn't know of any research that's formally looked at leeches as a way to speed up exercise recovery (nor could I find anything from a cursory expedition through PubMed), he says it isn't entirely out of the realm of possibility.
"For one thing, the saliva of leeches contains molecules that cause vasodilatation or dilation of blood vessels," he explained. "We know that dilated blood vessels can carry more nutrients, oxygen, and specialised cells that fight infection, repair damage, and do all manner of other jobs that need to be done to protect and repair the body. Dilated vessels are like adding lanes to the highways, making it easier and faster to transport materials (in this case, materials such as oxygen, biochemicals, cells) to where they are needed."
Leeches also spit out molecules like hyaluronidase, which are known to alter the physical structure of a host's tissue (again, though, I failed to find any clear research looking at a possible connection).
I've also reached out to LeechesUSA, the only company in the US allowed to sell FDA-approved leeches for medical use for their take, but haven't heard back yet.
In any case, it is clear that leeches are becoming a popular, low-cost treatment once again, especially in places such as Russia, where 10 million leeches are prescribed each year, according to an article from the Miami Herald last year. Sherman says it's tough to gauge the prevalence of leech therapy stateside, though he speculates that unapproved use might be anywhere from 10 to 20 times than what's officially recorded in hospitals.
The Polish leech firm, meanwhile, told Reuters it's exporting around 400,000 thousand leeches a year now. Yowza.