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Leech for Bushwalkers

Anne Parson

National Parks lind Wildlife 43 Bridge Strccl HursNilie

AARGH! A LEECH! sense vibrations through the water and will move to their Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/26/3-4/142/1473348/az_1990_006.pdf by guest on 27 September 2021 source Lo feed. I woke up wheezing for breath, hardly able to see through my swollen eyelids and unable to feel one side Once on an , leeches retreat from light, for of my face. OK, it was a hard days work; wet, co/d, fots example into socks, boot tops and collars. They feed for of mud, but this was a bit much. I just couJdn't figure it up to two hours consuming between two and ten times out . .. until f felt the funning down my neck. A their own weight (usually about 5 ml of blood) before leech bite! I had just discovered that I am allergic to they release their grip. One meal may last the leech for leeches! OK, so now what? find my antihistamine tablets, months. The blood is digested in the leech's stomach by use my inhaler and after a couple of hours start to feel a bacterium, which prevents the growth of other vaguely human again. Next step was a visit to my library organisms that may cause the blood to putrefy. in order to satisfy my curiosity about leeches. Here's what Bites rrom leeches are usually painless as the result of I learnt .. an anaesthetic secreted in the wliva (which may account for my numb face). Under the head they have What is a Leech? jaws with many sharp teeth. Aquatic leeches usually have three jaws and terrestrial leeches have two. Australian Leeches arc anne,lid worms from the Hirudinea. terrestrial leeches generally leave two short cuts in a 'V They usually have a sucker at either end of their shape in the 's skin. After the flesh is broken, a prob- body. The body is supported by a hydrostatic skeleton oscis may be inserted for feeding or the leech may which stiffens the body like a hose full of water (and simply suck from the skin surface. makes it very difficult to squash!). They are generally dark coloured with lighter stripes on their back, Most leeches secrete an polysaccharide hence the common name for some of Tiger known as in their . Similar Leeches'. are used in commercially available bruise treatments. TIlere are over 45 species of aquatic and terrestrial Removing Leeches leeches recorded in Australia. Adults generally range between 2 and 10 cm in length. The largest leeches Leeches should not be pulled off as this may tear the come from inland drainage systems and include the skin or leave mouthparts in the wound allowing it to genus Richardsonianus, a specirnen of which, measur- become ulcerated or infected. Leeches can be removed ing over 20 cm fully extended, was collected at Lightning by applying heat such as a smouldering twig, sprinkling Ridge. with salt or, more simply. by allowing them to drop off when engorged. Not all leeches arc parasites. many aquatic species eat insect larvae. snails, other worms and decaying vegeta- To save being attacked by the same leech again, such tion. Terrestrial leeches rely on the blood they extract as in a camp site, they can be drowned in a container of from passing birds, frogs, reptiles and , includ- soapy water. Squashing does not work well (remember ing humans. Leeches move by attaching their head that hydrostatic skeleton!). If you will be exposed to more sucker to a surface, arching their back bringing their leeches, change your socks or clothes and wash the hind sucker forward. holding on with it and then releas- blood off your skin. This lessens the likelihood of other ing their head sucker and reaching forward to repeat the leeches 'smelling' your old bites ("Ind attracted to you. action. Leech bites generally bleed slowly for a long time (10 minutes up to 5 hours). A band-aid on a leech bite will Leech Bites usually aid blood clotting. After about 12 hours most Walkers and passing collect leeches by brush- people suffer itchiness. which can be relieved by a ing against foliage where they rest. Leeches can sense number of over the counter preparations. such as light and heat with small receptors near their head and calamine lotion, tea tree oil and creams containing have scent organs in their skin. Aquatic leeches can lignocaine.

142 AUStriilii1n Zoologist, Vol. 26(3 & 4) September 1990 j

Leech Allergy Conservation Status

Some people develop an allergy to leech saliva. It The medicinal leech is now extinct in many parts of usually arises through repeated exposure to leech biles Europe. This is believed to have arisen from collection and these people usually carry treatments prescrihed by for blood letting and recent renewed collecting pressure- their doctor such as an inhaler spray, antihistamine or for m edical research. Habitat loss, for example through other tablets, and possibly injections. People with very draining of swamps causing a decrease in the number severe reactions or who are exposed to leeches in their of host frogs, has also contributed to the threatened occupation, can be treated using immunotherapy with status of the medicinal leech. leech extracts. Steps towards the protection of the medicinal leech Allergic reactions Illay riJnge from red, swollen welts have included bans on the collection and exportation of to anaphylactic shock. My signs of a reaction should be leeches from some countries, studies on the biology and treated seriously. If the person has a swollen throat, then conservation potential of some British popUlations, sucking ice may alleviate symptoms until they can obtain captive breeding programmes and chemical synthesis Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/26/3-4/142/1473348/az_1990_006.pdf by guest on 27 September 2021 medical treatment Artificial respiration should be of substances previously obtained from leeches. administered if the patient stops breathing. In Australia it appears likely that some of our leeches may eventually be threatened by loss of habitat The Avoiding Leech Bites most immediate threats to aquatic species arise through Apart from staying .!It home, there are a number of regulation and increasing salinity in inland rivers. methods to minimise leech bites. These include using Terrestrial species may be threatened by dearing of wet insecticide around socks and shoes, wearing fine weave forests in south-eastern Australia. socks with no seam holes at the ankles, sealing trouser As far as I can ascertain there has been no research legs to boots with tight socks, gaiters or ell:lstic bandages, as to the conservation status of leeches in Australia. I am or continually removing the leeches before they have an sure most bushwalkers and campers entertain the opportunity to bile. thought of leech extinction regularly, but this may not necessarily be a good thing. Who knows. someone may Medicinal Uses find another use for leeches besides and The medicinal leech Hirudio medicinalis, which has its annoyance. natural distribution throughout Europe, has been used ( since the early 1800's for in cases such as ACKNOWLEDGEMENTS black eyes, pleurisy, pericardItis, meningitis, appendicitis I thank Dr l. C. Lawrence MBBS (Hons) for his valuable and liver congestion. comments on this manuscript An active market for Australian native leeches was developed by 1835. They were collected by people REFERENCES wading bare-legged into swamps or by pegging the skin RICHARDSON. L. R., 1970. A contribution to the history of the of a freshly killed sheep to Cl river bed. In 1869 a cargo Australian medicinal leech. Australian Zoo/o.4isl 15: of the Australian leech Hirudio quinquestriata was 395-99. exported to London. SIMS. G., 1989. Leech Mania. Australian Geographic 14: 34-47. Today leeches are occasionally used in micro-surgery and skin grafting operations to lessen bruising and SlJrHERLAND, S. K., 1983. MAustralian Animal Toxins.M Oxford University Press: Melbourne. swelling through their and blood removing properties. UNDEHHlLl, D.. 1987. "Australia·s Dangerous Reader's Digest Sydney. Reproduc.tion WElLS. S. M., Pvt.£, R. M. AND COUJNS, N. M., 1983. The IUCN All leeches are , having both male and Red Dai

September J 990 I\ustrl!litm Zoologist, Val. 26(3 & 4) 143