Protect against bites by land leeches

[Psyche]

So true, but it is not a problem! However, I do not seem to get bitten by Mosquitos. Which would I prefer? .... Let me get bitten by leeches every time. At least I known they are harmless!

Lucky you. I have developed a hypersensitivity to leech bites. A bite will lead to angry red swelling, an oozy wound and a maddening itch. Even a light bite cause an itchy reaction.

More unnerving is the buffaloe leeches that live in water. These can stretch to 20cm. long.
You won't find me stepping into water at a river's edge if there are buffaloes around.
I once landed one in crystal-clear water next to a small waterfall, but I realised villagers have buffaloes further downstream & some may have wandered upstream. I don't think the leech made its way up against the current although it could do so close to the bank.

TL Seow

[teotp]

Another concern about leech bite is other bacterial pathogens like Burkholderia pseudomallei and Leptospira interrogans may take this opportunity to enter our body and cause melioidosis or leptospirosis. This is why I used lime juice (acid to lower the pH may kill some microorganisms) and/or drinking water (reduce the microorganism numbers) to wash the bited wound and then stop the bleeding after that, although there is no report about Burkholderia pseudomallei infection or leptospirosis after leech bite but preventive mearsure is very important in the field.

Teo T P

[teotp]

The purpose of this write is to share with BC members the distribution, biology, behaviour and some preventive measures against leeches with special reference to the land leech, Haemadipsa zeylanica.

Blood sucking land leeches (Haemadipsidae) are distributed throughout much of the tropical Asia, Australasia and Oceania (Moore, 1938; Keegan et al, 1968). The best known species is Haemadipsa zeylanica which lives in mainland Asia from about 4,000 m in the Himalayas of India and Nepal to the Asian countries, southern China, as well as on offshore Asiatic Islands like Sri Lanka, Sundas, Taiwan, and Ryukyus to Japan where it confined to certain mountains (Sawyer, 1986).

The following blood sucking land leeches (Haemadipsidae) of South East Asia were documented by Professor Roy T. Sawyer:

Haemadipsa ornate (Moore, 1927): Known from the eastern Himalayas (Darjeeling, north-east Frontier, especially Assam; 500 - 1,000 m).

Haemadipsa picta (Moore, 1929): Known from the Malay Peninsula, (?) Celebes and Borneo, where it is characteristic between the range of 700 - 1,300 m.

Haemadipsa sylvestris sylvestris (Blanchard, 1894): Known from north-east India (especially abundant in Assam) throughout Myanmar to Thailand.

Haemadipsa sylvestris interrupta (Moore, 1935): Known fron Malay Peninsula, Thailand, and Indo-China and probably Java and Sumatra.

Haemadipsa cochiniana (Moore, 1927): Common in southern part of India, extending north on the western coast to Bombay from sea level to 1,100 m.

Haemadipsa montana (Moore, 1927): Known from Myanmar hills, southern India, Himalayas, usually 2,000 - 2,700 m.

Haemadipsa zeylanica subabilis (Moore, 1929): Known from Malay Peninsula and west Sarawak.

Haemadipsa zeylanica sumatrana (Horst, 1883): Known from Sumatra and Borneo, where it is the common ground leech in all parts of the island except west Sarawak.

Haemadipsa zeylanica zeylanica (Moquin-Tandou, 1826): Sri Lanka.

Haemadipsa zeylanica agilis (Moore, 1927): The common leech of western Himalayas, very abundant in region around Naini Tal, 1,700 - 2,000 m (1,000 - 3,700 m); also occurs in southern Indian hills (Palni Hill, Madras, Dhoai Forest, South Malabar); uncommon in Nepal.

Haemadipsa zeylanica montivindicis (Moore, 1927): Known from eastern Himalayas (common in Daarjeeling district, Sikkim and Assam, 1,500 - 2,200 m (600 0 3,800 m)) and Myanmar (Dawna Hills).

To determine the local and seasonal distribution of Haemadipsa zeylanica and other leeches is highly relied on the availability of moisture. In continually moist areas, such as the mountain areas of Malaysia and Borneo, land leeches are more or less active throughout the year. On the other hand in those parts of its range (e.g. northern India) subject to periodic dry and wet seasons, abundance of H. zeylanica is highly seasonal. Localities teeming with active leeches in the rainy season are virtually devoid of them in the dry season. During rainy period H. zeylanica migrate considerable distances (1 km or more) vertically up hills and horizontally into area normally too dry, such as unforested pastureland. As the rain cease the leeches retreat from drier, exposed locales and by the advent of the dry season, they by now of moderate to large size, are confined to damp areas such as near streambeds. Nevertheless they never voluntarily enter water. As the topsoil dries out the leech burrow into damp subsoil. On digging a foot or more, below the earth surface and on turning the underground buried stones, and pebbles in the vicinity of water channels, a large number of hibernating leeches were everytime found, attached to under surface of the stones. At this time the individuals are sluggish and unresponsive. With the advent of the rainy season the leeches quickly revive, couplate at the first opportunity and actively seek for a blood meal.

The normal host of H. zeylanica living deep in the undisturbed rainforest is unknown, but those living in distrubed areas feed voraciously on domestic animals, especially cattle, as well as humans. In laboratory, H. zeylanica reported to feed on frogs, snakes, mice, rabbits and even chickens. Occasionally land leeches have been found on wild birds, sometimes in their nasal passage. Undoubtedly birds represent one mechanism of dispersal which explain the widespread distribution of land leeches in Oceania (Sawyer, 1986)

Teo T P

(to be continued...)

[teotp]

Throughout the range of H. zeylanica (ground leech) lives exclusively on ground among fallen leaves on the damp forest floor, but its relatives, H. ornate and H. picta, both of which climb low-lying bushes. H. zeylanica is especially active in mornings and early evenings. It has a highly developed sensory system, including extraocular photoreceptors, and foraging individuals are very responsive to ground vibrations and overhead shadows. They are particularly sensitive to near by flow breath, of which carbon dioxide is reportedly the main detected component. Ground leeches are also attracted to warmth, at least upon physical contact with a warm object H. zeylanica moves rapidly and with great agility over leaves toward a host from a distance at least 1 or 2 metres. Once attached they probe the host skin with anterior tip of the oral sucker and select a suitable site for feeding (Keegan et al, 1968; Sawyer, 1986). Penetration of the skin is achieved in a further 80 - 90 seconds and blood sucking last for about an hour, during which an adult leech would ingest about 1 g. or more of blood. The bite of H. zeylanica is painless, unlike the "stinging leeches" H. ornate and H. picta. Various leech species solved the clotting of blood in different ways by using their salivary secretion to (1) anti-thrombin (hirudin), (2) fibrinogenolysin (hemetin), (3) plasminogen-activation and (4) inhibition of platelet aggregation. Following a meal the bite continues to bleed for about 30 minutes but coagulation time is delayed for only 10 minutes. The sated animal drops off and retreats to a protected location in the forest floor. After 4 to 7 days the leech will become progressively more active (Sawyer, 1986).

Land leeches including H. zeylanica appear to be capable of transmitting trypanosomes to their host. The best documented case of this is the transmission of Trypanosoma aunawa by Leiobdella jawarerensis to bat (Minopterus tristris) in New Guinea cave (Ewers, 1974). Similarly, active trypanosomes are known to live in the crops of Chtonobdella bilineata and H. zeylanica for at least 52 and 44 days after the last meal respectively. The latter species has been implicated as a possible vector for Trypanosoma evansi, causative agent for surra, an often fatal disease for domestic animals (Sawyer et al, 1982).

In addition, aquatic leeches like Hirudinaria manillensis is extremely voracious and aggressive animal. If one agitates the water, the leeches emerge from their resting positions in the mud and swin energetically toward the focus of water disturbance. These leeches may actually leave the water and attach to the animal or observer's foot. Upon making physical contact with the host the leech quickly attaches. A good example is a car stuck in mud and water, was spining its wheels in an attemp to become unstuck. After a few minutes of this the driver noticed a number of aquatic leeches firmly attached to the overheated tyre. Nasal leeches are encountered in the nasal passage or other external orifices of humans and animals. Juvenile nasal leeches are very small and live in water. When an unsuspecting person or animal drinks directly from infected water, a leech may quickly attach to the mouth or nares. It subsequently lodges itself deep in the nasal passage where it lives for many days or weeks. Initially in conspicuous it sucks blood periodically and grows rapidly by which time it causes considerable discomfort to its victim. A reported case is one removed from the nose of a woman from Kinarut, 24 km south of Kota Kinabalu (Hii et al, 1978). A leech species identified as Dinobdella ferox has been reported in the nasal passage of dogs at Kinabalu and also free living in mountain stream (Harrison, 1953; Walton, 1955) (Do not drink or wash your face with stream water in forest!).

Finally, I would like to mention a repellent (M-1960) used by the U. S. Army and British Colonial Office during the Second World War in Borneo. Field tests of army uniforms treated with "M-1960" by volunteers gave complete protection against land leeches H. zeylanica, H. picta and water leech Hirundinaria manillensis. A measurable and useful degree of protection remained after six cold washes (Audy & Harrison, 1954; Sharma & Fernando, 1961). The authors reported that clothing treated with "M-1960" has a distinct smell but does not seem to be offensive to majority of wearers. Land leech placed on a freshly treated sleeve showed distress, refuse to hold it with suckers, writhe and wriggle and throw out mucus. If it was not removed or did not escape as a result of its struggles and become limp, comatose after 5 to 10 minutes and would never recover. Repellent "M-1960" was developed for the U. S. Army by USDA as a general repellent against mites, fleas, ticks and mosquitoes. It consists of:

n-butylaoetanilide -----------------30%
2-butyl-2-ethyl-1.3 propanediol ----30%
benzyl benzoate -------------------30%
tween 80 (emulsifire) --------------10%

Hope the above information is useful to BC members and jungle trackers from overseas. Cheers!

Teo T P

References:

Audy, J. R. & J. L. Harrison (1954). Field tests of repellent M-1960 against leeches. Medical Journal of Malaya 8, no.3: 240-250.

Ewers, W. H. (1974). Trypanosoma aunawa sp. n. from an insectivorous bat Miniopterus tristris in New Guinea, which may be transmitted by a leech. Journal of Parasitology 60, no.1: 172-178.

Harrison, J. L. (1953). Leeches. Medical Journal of Malaya 8, no.2: 180-185.

Hii, J. L. K., S. K. P. Kan & K. S. A. Yong (1978). A record of Limnatis maculosa (Blanchard)(Hirudinea: Arhynchobdellida) taken from nasal cavity of man in Sabah, Malaysia. Medical Journal of Malaysia 32, no.3: 247-248.

Keegan, H. L., S. Toshioka & H. Suzuki (1968). Blood sucking Asian leeches of families Hirudidae and Haemadipsidae. 406th Special Report of U. S. Army Medical Command, Japan. 130pp.

Moore, J. P. (1938). Leeches (Hirudinea) principally from the Malay Peninsula with descriptions of new species. Bulletin of The Raffles Museum 14: 64-80.

Sawyer, R. T., A. Taylor & Mohd. Jaya bin Hj. Sahat (1982). The leeches of Brunei (Annelida: Hirudinea) with a checklist and key to the known and expected freshwater, terrestrial and marine leeches of Borneo. Brunei Museum Journal 5, no.2: 168-201.

Sawyer, R. T. (1986). Leech biology and behaviour volume 2: feeding biology, ecology and systematics. Clarendon Press, 374pp.

Sharma, R. E. & C. H. Fernando (1961). Leeches and their ways. Malayan Nature Journal 15: 152-159.

Walton, B. C. (1955). The 'nasal leech' Dinobdella ferox from Borneo and Malaya. Journal of Parasitology 41, no.6: 32.

[Silverstreak]

Wow!! *Salute*

Thank You Thiam Peng for taking the time to research and sharing this !!

[teotp]

Wow!! *Salute*

Thank You Thiam Peng for taking the time to research and sharing this !!

Thank you for your nice words, Sunny.

Teo T P

[Commander]

Quite a lot of useful information there, TP. A good reminder not to underestimate these leeches, even though they may seem harmless when they bite us.

[Painted Jezebel]

Thanks very much for such detailed info, TP.

Much to think about when I leave my, fortunately, leech-free Island. I do usually carry limes and/or salt with me when on the mainland or abroad, but, I must admit, rarely use them.

[teotp]

Quite a lot of useful information there, TP. A good reminder not to underestimate these leeches, even though they may seem harmless when they bite us.

Thank you for your kind comments, SK. I was surprised when I read the "nasal leech" article.

Teo T P

[teotp]

Thanks very much for such detailed info, TP.

Much to think about when I leave my, fortunately, leech-free Island. I do usually carry limes and/or salt with me when on the mainland or abroad, but, I must admit, rarely use them.

Not at all, Les. I just don't want to see any BC member get infestation or any disease from these creatures after they return from the field.

Teo T P