Leeches (Class: Clitellata)

These segmented invertebrates, usually have a poorly-defined head and lack parapodia (‘legs’). The mouth is on the undersurface and the brain is located in one of the body segments.

The jawless leeches are known to harbour malarial parasites, but are not known to transmit these to humans and, while there is no scientific evidence that the jawed leeches, which feed on human blood, transmit diseases to their host, allergic reactions are not uncommon and the wound can become infected. The wound can also bleed and stay itchy and inflamed for several hours after the leech has dropped off.

While most leeches can be removed safely if discovered feeding on the human body (they can be made to drop off by touching them with a hot object, salt, eucalyptus oil or tea tree oil), leeches have been known to attach themselves to an eyeball and should not be removed forcibly. Any bite site should be treated with antiseptic to prevent infections, particularly if they have been pulled off by hand. They are also capable of causing pruritus and palpable purpura.

Leeches have been used for medicinal purposes for many years, and are used to assist in reattachment of severed body parts and in plastic surgery by reducing blood clotting in the finer tissues.