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THE EXPERTS CORNER
Year : 2015  |  Volume : 63  |  Issue : 3  |  Page : 300-303

Snakebite in India today


Centre for Herpetology, Madras Crocodile Bank, Chennai, Tamil Nadu, India

Date of Web Publication5-Jun-2015

Correspondence Address:
Romulus Whitaker
Centre for Herpetology, Madras Crocodile Bank, Chennai, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.158155

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How to cite this article:
Whitaker R. Snakebite in India today. Neurol India 2015;63:300-3

How to cite this URL:
Whitaker R. Snakebite in India today. Neurol India [serial online] 2015 [cited 2019 Sep 15];63:300-3. Available from: http://www.neurologyindia.com/text.asp?2015/63/3/300/158155


"In January, 1870, being then in Calcutta, I collected statistical information which afforded proof that the loss of human as well as animal life in India from the bite of venomous snakes was very great; and as it seemed to me that this ought to be, to a great extent, preventable, I extended my investigations with the view of obtaining accurate information as to the characters and peculiarities of the venomous snakes themselves, the localities in which they most abound; the modus operandi of the poison; the circumstances under which the bites are inflicted; the value of any known remedies in the treatment of those bitten, and what measure might possibly be devised for diminishing this serious evil…" {Joseph Fayrer, Professor of Surgery, Calcutta Medical College, 1883}.

In the 'pre-antivenom' days of 1883, when Dr. Fayrer was deeply immersed in India's 'thanatophidia,' there were a reported 19,060 deaths by snakebite in India when the population was less than half of what it is today. It is revealing that well over a hundred years ago, there was a major effort to study and deal with the problem of snakebite. In 2015, we are looking at a sadly similar situation, but the current estimate of deaths by snakebite in India has dramatically increased (as has our population). [1] Reliable statistics are only now available, thanks to the Million Death Study, an initiative of the Registrar-General of India and the Centre for Global Health Research at St. Michael's Hospital and the University of Toronto, Canada. [2] Based on this study, the upper estimate for snakebite deaths in India is a staggering 50,000 per year. Tens of thousands more snake-bitten persons who survive will suffer amputations or other severe injuries due to snakebite.

The primary victims of snakebite are farmers, rural labourers and their families. Most bites are on the feet and legs and occur after sunset. There are four snakes that are held responsible for most of the serious snakebites: Russell's Viper, Spectacled Cobra, Common Krait and Saw-scaled Viper, popularly known as the Big Four [Figure 1],[Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6],[Figure 7] and [Figure 8]. Complicating the issue is the fact that India has four species of cobras, eight species of kraits and one subspecies of saw-scaled viper, besides a number of other venomous species. [3],[4],[5],[6],[7],[8],[9] But more about this later.
Figure 1: Cobras are better rat eradicators than cats!

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Figure 2: Common krait. (Photograph taken by Nikhil Sanger)

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Figure 3: The author collecting Russell's viper venom

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Figure 4: The author with his guru, Bill Haast, feeding a king cobra at Miami serpentarium, 1964

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Figure 5: The author with the prairie rattlesnake that bit him. El Paso, Texas, 1966

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Figure 6: Russell's viper probably causes most serious bites

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Figure 7: Saw-scaled viper from Rajasthan

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Figure 8: Spectacled cobra, found throughout most of India

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Let's be quite clear: Snakes are not 'out to get us'; they are normally shy, retiring animals who are more than happy to steer clear of dangerous humans. However, they will defend themselves when they feel threatened (like when stepped upon). But let's also be clear that snakes are indeed common in some parts of the country. One reason is our propensity to encourage and tolerate rats and mice to live in our homes and fields, a sure attractant to hungry snakes.

The only treatment for venomous snakebite that has any value (despite what you might hear) is an injection of antivenom. Antivenom is derived by immunizing horses with snake venom in gradually increasing doses until the horse reaches a high titre of immunity to the venom. The horse's hyper-immune serum is then refined into antivenom. All Indian antivenoms are polyvalent, that is, they are effective against all the Big Four common venomous snakes of India. [3],[10]

Unfortunately, the Indian antivenom is woefully low in potency, much lower than it was in the 1950s! Cobra antivenom of the 1950s was six times more potent at 4 mg/ml than the current potency of 0.6 mg/ml! Inexplicably, the efficacy of antivenom has greatly reduced in recent years and something must be done to remedy this sad situation. For example, a 10 ml vial of antivenom is rated to neutralize 6 mg of cobra venom. However, one study showed that cobras may inject as much as 742 mg of venom at a time. A 10 ml vial of antivenom costs about Rs. 500 and though Indian antivenom manufacturers have managed to produce what is surely the cheapest snakebite cure in the world, it is not up to par. For example, considering the above quoted dosage of cobra venom, it might take 165 vials of India's low-titre antivenom to neutralize a bite, for a cost of Rs. 82,500! This would be way beyond the means of a farm labourer, and explains part of the reason why India's snakebite mortality is the highest in the world. Obviously rural snakebite victims are more likely to seek cheap (but useless) cures provided by 'alternative medical practitioners' including herbs, snakestones and other mumbo-jumbo. Though none of these work in the case of a real venomous bite, there are enough non-venomous bites, 'dry' bites and bites with sublethal doses to provide an illusion of success.

Since there are several different kinds of cobras and kraits in the country, it would make more sense to use a mixture of their venoms to make sure that we are covering all possible venom components. Venoms even from the same species may vary from place to place and though few adequate studies have been done, it has become apparent that there are geographic variation problems with the available antivenom. Some doctors speak of giving close to 100 vials of antivenom when a mere 10 or 20 should be more than sufficient for any bite. Part of the reason could be that the main source for venoms is the Irula Snake-catchers Industrial Cooperative Society which collects snakes from two districts in Tamil Nadu. Ideally, venom should be collected from the 'four corners' of India to ensure that the antivenom is effective throughout the country.

Other venomous snakes of India that can cause serious, even fatal bites are some of the 23 species of sea snakes, the King Cobra and perhaps a few of the 20 species of pit viper. There is no antivenom in India for the bites of any of these. Luckily, sea snake and King Cobra bites are extremely rare, and though pit viper bites are common in tea estates, most of the species involved have milder venom which causes pain and swelling and not much else. One little pit viper, known as the Hump-nosed Pit viper and common in parts of the southern part of the Western Ghats, has caused deaths in Sri Lanka. Interestingly, there are parts of the country, such as the Northeast, and Andaman and Nicobar Islands where there are no Common Kraits, Russell's or Saw-scaled Vipers [Figure 1],[Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6],[Figure 7] and [Figure 8]. These areas have far fewer snakebite deaths, but there is no antivenom for the venomous snakes that do occur there. [8]

Today, there are six pharmaceutical companies in India producing a total of close to two million vials of antivenom each year. Published results of snakebite and venom studies indicate that there is plenty that can be done to improve the potency of antivenom and reduce the reportedly high incidence of allergic reactions to antivenom. Recently, a venom study has been started by the Centre for Herpetology/Madras Crocodile Bank in collaboration with toxinologists [Figure 9]. In the first phase, the mandate is to test the efficacy of Indian antivenoms against the venom of one snake in particular, the Russell's Viper, the snake that is responsible for a high percentage of serious bites and fatalities. The objective is to collect Russell's Viper venom samples under a specialized protocol from 10 different representative localities in India and carry out what is known as the ED 50 test to see if the antivenom (produced using venom collected in Tamil Nadu) neutralizes the effects of the venom no matter which part of the country the snake is from. The aim is to assist the antivenom producers to optimize their product which will save many more lives and limbs. [10],[11]
Figure 9: Venom collection from Russell's viper

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In my personal experience with snakebite, I've had the dubious honour of being bitten in the USA by Prairie and Green Rock Rattlesnakes and Cottonmouth Water Moccasin; by a Black Whip Snake in Australia; and, have had dry bites by a Malabar Pit Viper and a Russell's Viper here in India. I admit that each bite was due to extreme foolishness on my part. Though very painful, these bites were fascinating experiences and only strengthened my resolve to help people deal with snakebite as one avenue toward raising acceptance of these much-maligned, and yet very useful denizens of our fields and forests.

 
  References Top

1.
Kasturiratne A, Wickremasinghe AR, de Silva N, Gunawardena NK, Pathmeswaran A (2008). The global burden of snakebite: A literature analysis and modelling based on regional estimates of envenoming and deaths. PLoS Med 5 (11): e218. doi: 10.1371/journal.pmed. 0050218  Back to cited text no. 1
    
2.
Mohapatra B, Warrell DA, Suraweera W, Bhatia P, Dhingra N, Jotkar R, Whitaker R, Jha P (for the Million Death Study Collaborators) (2010). Snakebite mortality in India: Nationally representative mortality survey of 1.1 million homes. http://www.plosntds.org/article/info%3Adoi%2F10.1371%2Fjournal.pntd. 0001018. [Last accessed on 2015 May 03].  Back to cited text no. 2
    
3.
Warrell DA. (2010). Guidelines for the management of snake-bites. World Health Organization South-East Asia Regional Office, New Delhi. 152 pp. Available as a PDF from http://www.searo.who.int/LinkFiles/BCT_Snake_Bite_Guidelines.pdf. [Last accessed on 2015 May 03]  Back to cited text no. 3
    
4.
Whitaker R. Notes on bites by the saw-scaled viper, Echis carinatus in the Deogad area of Ratnagiri District, Maharashtra. JBNHS 1970; 67: 335-337.  Back to cited text no. 4
    
5.
Whitaker, R. Pit viper (Trimeresurus macrolepis) bites at a south Indian tea estate. J Bombay Nat Hist Soc 1973; 70;130-131.  Back to cited text no. 5
    
6.
Whitaker, R. Snakes responsible for snakebite and their natural history. Proceedings, Seminar on the Diagnosis and Treatment of Snakebite. The Indian Pharmacological Society and Madras Snake Park Trust, August 1977.  Back to cited text no. 6
    
7.
Whitaker, R. (1991). Suspected case of death by pit viper bite. Hamadryad 1991; 16: 38.  Back to cited text no. 7
    
8.
Whitaker R, Captain A. Snakes of India-the Field Guide. Draco Books, Chengalpattu, India. 2004 pp 481.  Back to cited text no. 8
    
9.
Whitaker R, Whitaker S. Analysis of snakebite data from Pappinisseri Vishachikilsa Society, Kannur, Kerala. Calicut Med J 2004: 4:2:c2, 1-8.  Back to cited text no. 9
    
10.
Whitaker R, Whitaker S. (2012). Venom, antivenom production and the medically important snakes of India. Current Science 2012; 103 (6).  Back to cited text no. 10
    
11.
Patwari P, Sangle S, Mane AA, Doshi S, Kadam D. Comparative study of electrophysiological changes in snake bites. Neurol India 2015;63:378-81.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]

This article has been cited by
1 Comparative analyses of putative toxin gene homologs from an Old World viper, Daboia russelii
Neeraja M. Krishnan,Binay Panda
PeerJ. 2017; 5: e4104
[Pubmed] | [DOI]



 

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