A leech bite often goes unnoticed initially, attributed to biochemical compounds in the leech’s saliva. These compounds create a painless feeding experience, preventing the host from sensing the attachment. This adaptation allows the leech to feed undisturbed, a unique evolutionary strategy.
The Bite’s Deception
Leeches possess specialized oral structures and secrete bioactive molecules for stealthy feeding. When a leech attaches, it uses three sharp jaws to create a precise, Y-shaped incision, a hallmark of a leech bite. Simultaneously, it releases substances from its salivary glands into the wound.
An anesthetic immediately numbs the bite area. This prevents the host from feeling the initial cut or the leech’s presence, allowing undisturbed feeding. Leech saliva also contains anticoagulants like hirudin. Hirudin inhibits thrombin, a protein essential for blood clotting, ensuring free blood flow. This potent effect prevents clot formation at the bite site.
Beyond numbing and preventing clotting, leech saliva includes vasodilators like histamine-like substances and acetylcholine. These compounds widen blood vessels near the bite, increasing blood flow. This ensures a steady blood supply for the feeding leech. This combination of anesthetics, anticoagulants, and vasodilators creates an efficient feeding environment. Leeches often remain attached for 20 to 40 minutes, expanding significantly as they engorge with blood.
What Happens After the Leech Detaches
After feeding, a leech typically detaches on its own, becoming engorged and much larger. The saliva’s effects linger, leading to noticeable post-bite symptoms. Persistent bleeding from the wound is common. Due to injected anticoagulants, the bite site can ooze blood for several hours, sometimes up to 7 days. This prolonged bleeding results from inhibited clotting mechanisms.
After bleeding, the bite area often becomes itchy, red, and may swell. This irritation is a common reaction to the saliva’s components, often attributed to histamine release and signaling the body’s healing. The wound typically presents as a characteristic Y-shaped or star-shaped mark, reflecting the precise incision made by the leech’s three jaws. While generally harmless, this distinct mark, coupled with continued oozing and itching, helps identify a leech bite.
Safe Removal and Care
If a leech is attached, encourage its detachment without causing injury or complications. Avoid forcefully pulling a leech off, as this can leave mouthparts embedded, increasing infection or irritation risk. Gentle methods are recommended. An effective technique uses a fingernail, credit card edge, or similar thin, blunt object to slide under the leech’s oral sucker, breaking suction. Once suction is broken, the leech will release its grip and can be flicked away.
After removal, proper wound care prevents infection and manages lingering effects. Clean the bite site thoroughly with soap and water. Apply gentle, direct pressure with a clean cloth or sterile bandage to control continued bleeding. Cover the wound with a sterile dressing and change it regularly, especially during initial oozing.
Monitor the bite site for signs of infection. Increased redness, warmth, swelling, pus, or fever warrant prompt medical attention. While rare, an allergic reaction to leech saliva may occur, manifesting as hives, dizziness, or difficulty breathing, requiring immediate emergency care.