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Leeches are segmented worms – a bit like giant earth worms. Most leeches live in fresh water environments but some species can be found in sea water and in terrestrial environments. They are quite common in tropical rain forests in South America and South East Asia where they live in leaf litter and vegetation.

Leeches can vary in length from a few millimetres to 10 or 20cm – and of course they get bigger as they feed…


Most leeches prey on small invertebrates but some species like to feed on blood – and if they happen to come across a human being they’ll think it’s Christmas, with no fur or feathers or scales or anything else to get in the way – just naked skin with warm blood pulsating below, just a single bite away…

Leeches find their prey by using a combination of olfactory sensors (chemical and smell detectors) and movement and vibration sensors. Consequently, they can both ‘smell’ and ‘feel’ you coming, and if you stand still for a few minutes in a leech infested area you may see them dropping from vegetation and inching towards you.

Leeches use their suckers (one at each end of their body) to manoeuvre into position and then attach themselves by biting their victim. The bite is usually painless because they release an anesthetic to prevent the host from feeling them, thereby reducing the likelihood of discovery. Once attached they also release an anticoagulant into the host’s bloodstream to keep the blood flowing whilst they feed. If they are left alone they will detach themselves and depart after they have finished feeding, which could take anywhere from 20 mins to 2 hours or more.

Firstly – what you shouldn’t do – don’t just rip it off. If the mouth parts of the leech are firmly attached you may leave them behind in the wound, thereby increasing the risk of the wound becoming infected.

Secondly – what isn’t recommended – it’s quite easy to remove a leech by applying a flame, a lit cigarette, salt, soap or a chemical such as alcohol, vinegar, lemon juice or insect repellent. The leech will detach itself quite quickly but it’s also likely to regurgitate some of the contents of its stomach into the wound in its haste, thereby increasing the risk of the wound becoming infected.

Thirdly – the recommended technique:

– identify the oral sucker at the anterior (mouth end) of the leech – generally this is the thinner end of the leech

– put your finger or some other flat, blunt object on the skin adjacent to the oral sucker and then slide it under the sucker to break the seal, at which point the leech will detach its jaws

– repeat the process with the sucker at the posterior (rear end) of the leech – generally this is the thicker, bloated end of the leech. Take care to ensure that the leech doesn’t reattach itself at the other end!

– clean the wound and bandage it. Bleeding may continue for some time because of the anticoagulant – it could be anything from a few hours to a few days. The wound normally itches as it heals and care should be taken not to scratch it, thereby increasing the risk of infection.

Generally no – leeches often carry parasites in their digestive tracts but they can’t survive in humans and hence they don’t pose a threat. Very rarely though leeches have been known to pass on disease from one human to another that’s carried in the blood they have consumed. The biggest risk is from infection in the wound after the leech has dropped off or been removed, so the wound should always be cleaned and bandaged.

This is one of the most important questions because prevention is always much better than cure:

Be aware – know where to expect leeches so that you know when to take precautions to protect yourself.

Cover up – wear long sleeved tops and long trousers, and tuck your trouser legs into your socks. Wearing gaitors, leech proof over socks and insect repellent clothing can also help enormously.

Use an insect repellent – insect repellent can help to protect any exposed areas. Clothing can also be treated with LifeSystems EX4 permethrin clothing spray to make it insect repellent.

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