Wednesday, May 25, 2011

Venomous Snakes Dangerous and Habitat Of South-East Asia

The geographical area specifically covered by this publication extends from Pakistan and the rest of the Indian subcontinent in the west through to the Philippines and Indonesia in the east, excluding Tibet, China, Taiwan, Korea, Japan, the eastern islands of Indonesia and New Guinea and Australia. In many parts of this region, snake bite is a familiar occupational hazard of farmers, plantation workers and others, resulting in tens of thousands of deaths each year and innumerable cases of chronic physical handicap. Much is now known about the species of venomous snakes responsible for these bites, the nature of their venoms and the clinical effects of envenoming in human patients. This publication aims to pass on a digest of this knowledge to medical doctors, nurses, dispensers and community health workers who have the responsibility of treating victims of snake bite.

Sumatran Cobra

The guidelines are intended to provide enough practical information to allow any medicallytrained person to assess and treat a patient with snake bite at different levels of the health service. Recommendations are based on clinical experience and, where possible, on the results of clinical trials. The restrictions on the size of this
document prevented the inclusion of detailed references to the original publications on which these recommendations were based. These can be found in the papers and reviews listed in “Further Reading”.

I am grateful to the panel of experts who contributed to these Guidelines but I must take responsibility for the writing and editing of the document. I acknowledge the exellent help provided by Miss Eunice Berry (Centre for Tropical Medicine, University of Oxford), who typed the several drafts of the manuscript, and by Ms Vimolsri Panichyanon (Assistant Programme Coordinator, SEAMEOTROPMED Network) and Drs Suvanee Supavej and Parnpen Viriyavejakul (Deputy Assistant Deans for International Relations, Faculty of Tropical Medicine, Mahidol University) who, under the overall direction of Professor Sornchai Looareesuwan, were responsible for organising the meeting of the international panel of experts in Bangkok
on 29/30 November 1998.

Venomous Snakes of South-East Asia

Venomous snakes of medical importance have a pair of enlarged teeth, the fangs, at the front of their upper jaw. These fangs contain a venom channel (like a hypodermic needle) or groove, along which venom can be introduced deep into the tissues of their natural prey. If a human is bitten, venom is usually injected subcutaneously or intramuscularly. Spitting cobras can squeeze the venom out of the tips of their fangs producing a fine spray directed towards the eyes of an aggressor.

There are two important groups (families) of venomous snakes in South-East Asia Elapidae have short permanently erect fangs. This family includes the cobras, king cobra, kraits, coral snakes and the sea snakes. The most important species, from a medical point of view, include the following:

cobras: N naja common spectacled Indian cobra
(genus Naja) N oxiana North Indian or Oxus cobra
N kaouthia monocellate cobra
N philippinensis Philippine cobra
N atra Chinese cobra
spitting cobras: N siamensis
N sumatrana
N sputatrix etc
king cobra: Ophiophagus hannah
kraits: B caeruleus common krait
(genus Bungarus) B candidus Malayan krait
B multicinctus Chinese krait
B fasciatus banded krait
Sea snakes (important genera include Enhydrina, Lapemis and Hydrophis)

Viperidae have long fangs which are normally folded up against the upper jaw but, when the snake strikes, are erected. There are two subgroups, the typical vipers (Viperinae) and the pit vipers (Crotalinae). The Crotalinae have a special sense organ, the pit organ, to detect their warm-blooded prey. This is situated between the nostril and the eye.

identify venomous snakes There is no simple rule for identifying a dangerous venomous snake. Some harmless
snakes have evolved to look almost identical to venomous ones. However, some of the most notorious venomous snakes can be recognised by their size, shape, colour, pattern of markings, their behaviour and the sound they make when they feel threatened. For example, the defensive behaviour of the cobras is well
known : they rear up, spread a hood, hiss and make repeated strikes towards the aggressor. Colouring can vary a lot. However, some patterns, like the large white, dark rimmed spots of the Russell’s viper, or
the alternating black and yellow bands of the banded krait, are distinctive. The blowing hiss of the Russell’s viper and the grating rasp of the saw-scaled viper are warning and identifying sounds.


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