They strike disgust in the hearts of lake swimmers everywhere. Leeches, those squirmy, blood-sucking pond dwellers, fell out of favor as a medical treatment more than a century ago. But a new study examining their effect on knee arthritis may put them back in the medical community’s good graces.German researchers studied 51 arthritis patients, 24 of whom were given a single treatment with four to six leeches. The leeches were applied to painful points on the knee for about 70 minutes, until they detached by themselves. The other patients had a standard arthritis treatment—a 28-day regimen of topical diclofenac.
After seven days, the leech-treated patients reported that their pain had reduced from 53.5 to 19.3 on a standard pain measuring scale. The patients who received the standard treatment reported a lesser pain reduction, from 51.5 to 42.4. Benefits of the leech treatment continued through 91 days of follow-up, according to the report.
The study was published in the Annals of Internal Medicine.
The authors of the study, Dr. Gustav J. Dobos from Kliniken Essen-Mitte, and colleagues, suggest that leech saliva has anti-inflammatory properties.
In a related editorial, Dr. Marc C. Hochberg said this study could lead to a treatment that uses the chemicals in leech saliva, while leaving the slimy critters alone.
Though the research subjects tolerated the treatment well, some patients could be deterred by the "yuck factor" involved in leech treatment. Leech treatment does also carry some risk of infection.
"The more exciting aspect of this work is the potential for the discovery of a novel analgesic agent that could be safely administered without the need for a leech bite," he wrote.
But he criticized some aspects of the study. All of the patients in the study knew which treatment they were receiving, which could have caused a placebo effect. The leech-treated patients may have imagined that their inflammation reduced more than it actually did. This is an especially high risk because the patients determined their own pain scores.
"At the moment, however, on the basis of these data I am not ready to refer my patients with knee osteoarthritis for leech therapy," he wrote.
Leeches are not merely a blast from the medical past: they are also used today to treat blood-clotting problems after surgery.
