Newcastle Newcastle (UK), Nov 9 (The Conversation) As we tidy away the Dracula capes and glow-in-the-dark plastic fangs for another winter, one notorious blood sucker has had a particularly good year. For the first time the medicinal leech Hirudo medicinalis has been bred in captivity at London zoo, part of a longer-term project to help this fascinating if unloved creature. Once widespread in the UK, the medicinal leech is now rare due mainly to habitat loss and historic collecting for medical use.
In Ireland, the leech was driven to extinction in the 19th century. Their vulnerability is recognised in international conventions and biodiversity audits. You may have heard about leeches being used indiscriminately to treat all kinds of illnesses, from cancer to mental illness in the 19th century.
The discrediting of general “bleeding” as a treatment for everything from hysteria to syphilis in the 19th century largely put an end to this history. However, in 1884 leech saliva was identified as an anticoagulant, called hirodine. Surgeons still use leeches to improve the success rates of surgery, such as when reattaching severed fingers as their saliva prevents post-surgery blood clotting inside veins.
The leeches’ medical comeback The medicinal leech was once widespread in Britain and Ireland. Their popular use in medicine resulted in a lucrative international market in the 18th and 19th centuries. They seem to have been a bit of a luxury treatment, too expensive for the poor.