Snakes are remarkable animals, successful on land, in the
sea, in forests, in grasslands, in lakes, and in deserts. Most snake bites are caused by non-venomous
snakes. Of the roughly 3,000 known species of snake found worldwide, only 15 percent
are considered dangerous to humans (Russell, 1990). Snakes are found on every
continent except Antarctica. The most diverse and widely distributed snake family,
the Colubrids, has only
a few members which are harmful to humans. Of the 120 known indigenous snake species
, only 20 are venomous to human beings, all belonging to the families
Elapidae (John Henkel, 1995). However, in the
United States, every state except
and Hawaii is home to at
least one of 20 venomous snake species
(John Henkel, 1995).
Consequently, no accurate study has ever been conducted to determine the frequency
of snakebites on the international level. However, some estimates put the number
at 2.5 million bites per year, resulting in perhaps 125,000 deaths. Worldwide, snake
bites occur most frequently in the summer season when snakes are active and humans
are outdoors (Wingert and Chan, 1988).
regions report more snake bites than anywhere else (Russell, 1990). Snakes are most likely to
bite when they feel threatened, are startled, provoked, and/or have no means of
escape when cornered. Encountering a snake is always considered dangerous and it
is recommended to leave the vicinity.
As far as Indian snakes are concerned, it's not the only
way either. A variety of poisonous snakes kill 50,000 Indians a year. In fact as
many people die of snakebites in
as the rest of the world put together (John Sudworth, 2006).
Snakes have no limbs, yet all are meat eaters. They catch
prey that includes insects, birds, small mammals, and other reptiles, sometimes
including other snakes. Only about 400 of 3000 snake species worldwide inject venom
Many snakes catch their prey by constriction. In constriction, a snake suffocates
its prey by tightening its hold around the
or causing direct
Snakes do not kill by crushing prey. Some snakes grab prey with their teeth and
then swallow it whole. Snakes are cold-blooded. Thus, they are unable to increase
their body temperature and stay active when it is
outside. They are most active at 25-32°C (77-90°F).
Based on their morphological characteristics including arrangement
of scales, dentition, osteology, myology, sensory organs etc., snakes are categorized
into families. The families of venomous snakes are Atractaspididae, Elapidae, Hydrophidae
The major families in the Indian subcontinent are, Elapidae which includes common
cobra, king cobra and krait, Viperidae which includes Russell's viper, pit viper
and saw-scaled viper and Hydrophidae, the sea snakes( Philip,1994). Of the 52 poisonous
, majority of bites and consequent mortality is attributable to 5 species viz. Ophiophagus
hannah (king cobra), Naja Naja (common cobra), Daboia rusellii
(Russell's viper), Bungarus caeruleus (krait) and Echis carinatae
How snakes bite
Snakes that inject venom use modified salivary glands. Venom is a modified
form of saliva and probably evolved to aid in chemical digestion. Varying degrees
also make it useful in killing prey. During envenomation (the bite that injects
venom or poison), the venom passes from the venom
into the snake's fangs, and finally into its prey. Snake venom is a combination
of numerous substances with varying effects.
The most common symptoms
of all snake bites are panic,
fear and emotional instability,
which may cause symptoms such as
tachycardia, and cold, clammy skin (Kitchens and Van Mierop,
The time onset of poisoning is similar in different species.
Cobra produces symptoms as early as 5 minutes (Paul, 1993) or as late as 10 hours
(Reid, 1979) after the bite. Vipers take slightly longer - the mean duration of
onset being 20 minutes (Paul, 1993). However, symptoms may be delayed for several
hours. Sea snake bites almost always produce myotoxic features within 2 hours so
that they are reliably excluded if no symptoms are evident within this period (Paul,
Based on the predominant constituents of venom of a particular
species, snakes were loosely classified as neurotoxic (notably cobras and kraits),
hemorrhagic (vipers) (Bhetwal et al., 1998) and myotoxic (sea snakes).
Since the act of delivering
venom is completely voluntary, all venomous snakes are capable of biting without
injecting venom into their victim. Such snakes will often deliver such a "dry
bite” rather than waste their venom on a creature too large for them to eat. Dry
snake bites, and those inflicted by a non-venomous species, are still able to cause
severe injury to the victim. There are several reasons for this, a snake bite which
is not treated properly may become
infected (as is often reported by the victims of viper bites
whose fangs are capable of inflicting deep puncture wounds), the bite may cause
anaphylaxis in certain
people, and the saliva
and fangs of the snake may harbor many dangerous microbial contaminants, including
tetani. If neglected, an infection may spread and potentially
even kill the victim.
Most snake bites, whether
by a venomous snake or not, will have some type of local effect. Usually there is
minor pain and redness,
but this varies depending on the site. Bites by
vipers and some cobras may be extremely painful, with the local
tissue sometimes becoming tender and severely
swollen within 5 minutes. This area may also
Healing tradition of Kerala
Healing tradition of Kerala includes
both Codified and non codified systems, which are
strongly interrelated and based on principles of Ayurveda. It involves classical
methods of diagnostics and treatment like Sushrutha Samhitha and Ashtanga Hridaya.
Visha Vaidya is one component of the healing tradition of Kerala.
Visha Vaidya is one branch of traditional healing, popular
in Kerala, mostly in Palakad and Trichur,
involving treatment of poisonous bites like that from snake, dog and stings of scorpion,
Visha Vaidya deals with management of poisonous bites, poisonous
substances and their action, Antidotes and Understanding of poisonous creatures. Treatment include herbals,
administered as nasal drops, eye drops and oral medicine, strict food regulations,
Abstaining from alcohol and non vegetarian foods. Treatment also includes rituals
and offerings to God.
Tribal Information from Kerala
The Kani tribe of the Western Ghats of Kerala apply ‘Vishakallu’, a medicated stone
with anti - poisoning properties to the affected area (snake bite). The ingredients that go into the making of ‘Vishakallu’
are, Pebbles from the
river, Tulsi or Holy Basil leaves (Ocimum
sanctum - Lamiaceae),
Leaves of Perumthumba (Anisomeles malabarica
- Lamiaceae), Heartwood
of Chandanam (Santalum album -
Mode of preparation of ‘Vishakallu’
Pebbles are ground, mixed with the other ingredients and made into paste and wrapped
with 7 leaves of Aristolochia tagala. It is
fire made by burning wood of Chuvannakil (Chukrasia tabularis – Meliaceae;
) or Dysoxylum malabaricum (Vella
Akil; Meliaceae), sandalwood, holy basil and camphor.
This baked cake is covered with paste of termite mount soil and again baked on low
The soil coat
is removed and the cake is soaked in water for an hour, covered with paste of Pittosporum
neelgherrense - Analivegam ( Pittosporaceae) stem bark . The whole thing
is baked again
and covered with stem bark of Kunstelaria keralensis (Fabaceae). And sun
dried. This ‘stone’ is stored in burnt cow dung ash and Nicotiana tabacum -
Pukayila (Solanaceae) leaves (Tobacco).
Mode of administration of ‘Vishakallu’
It is administered
only by experienced tribal healers. The stone is directly applied to the bitten
part. It sticks there and absorbs the venom from the wound. During this operation,
Lord Siva is propitiated by chanting mantras. When all the venom is absorbed the
stone falls away automatically.
is immersed in cow’s milk for detoxification for 2 hours.It is again dried and stored
in cow dung ash. It is believed from experience that it can be used 20 times.
Plants for snake bite
Plants and their extracts
have been used for the treatment of snake bite in most areas where venomous species
are endemic (Houghton and Osibogun, 1993). In spite of this wealth of ethnopharmacological
information only a relatively few species have been tested scientifically for anti
– venom activity and the species where an active compound has been isolated are
very few in number.This report lists the plants used by the traditional healers
against snakes and snake bite in India.
Plants used against snake bite in
Although many plants may not neutralize the venom itself,
they may be used to treat snake bite because they alleviate some of the symptoms
(fear and panic) by tranquilising compounds eg: Rauwolfia
serpentina – ‘Sarpagandhi’ (Apocynaceae)
since this plant containing the tranquilising alkaloid, Reserpine.
Some species are grown
around houses or their extracts sprinkled on the floor to repel snakes. e.g., Garlic
Allium sativum ;
Liliaceae) and Garlic vine (Pseudocalyma
Some plants may stimulate the immune system thus having beneficial
effects, helping in removal of the venom.
In this context, Aristolochia
species (Aristolochiaceae) is noteworthy. It contains Aristolochic acid which is
an immune stimulant.
Plants with analgesic and anti - inflammatory effects may
lessen the inflammation and pain caused by snake bites. e.g.,
Rhapidophora pertusa -
Aristolochia indica and A. tagala
of Aristolochiaceae are two plants, used by the Kanis to treat snake bite (krait
& cobra).They call them ‘Cheriya arayan’
and ‘Veliya arayan’ respectively.
According to them, A. tagala
is more potent than A. indica. A. indica
was used as antidote to snake bite by ancient Ayurvedic physicians also. It
is an excellent blood purifier, used as diuretic, heart stimulant and against skin
diseases. Paste of fresh leaves or roots of
A. indica or A. tagala
is applied externally over the bitten part. 10 – 15 ml fresh juice from leaf/ root
with a pinch of black pepper is administered orally 6 times a day.
The whole plant of
A. indica or A. tagala
(1 part), bark of Ficus religiosa –
1 part and powder of black pepper (1 part) are mixed together and used as
nasal inhaler to recover from the coma caused by snake bite.
The leaves of
Cipadessa baccifera (Kattuveppu;
Meliaceae) are mixed with pepper and taken orally against snake bite by Malapandaram
tribe of Wayanad, Kerala.
Other major plants
for snake bites
Strychnos nux vomica
Seeds and Roots
Root and Seeds
Kani and Malapandaram
Leaves and Roots
traditional healers of Kerala
Crushed stem bark
Major phytocompounds responsible for anti venom activity
Aristolochic acid from Aristolochia species (Aristolochiaceae)
is reported to inactivate venom and reduce hemorrhage from snake bite.It inhibits
phospholipases. It produce non - specific increase in immune response (Wagner and
Gymnemic acids (triterpenoid glycosides) from Gymnema sylvestre (Chakkarakolli;
Asclepiadaceae) is used as a remedy for snake bite in
. It inhibits ATP ase in snake venom (Kini and Gowda,
Eclipta prostrata (Kaiyonni;
Asteraceae) extracts inhibit effects of South American rattle snake bite. Three
active compounds, coumestan, wedelolactone stigmasterol and sitosterol have been
isolated from the crude extract this plant (Mors et al., 1989).
like tannins are well – known for their ability to bind with proteins. The tannin
from Diospyros perigrina
(Panichi; Ebenaceae) inhibits swelling
in feet of mice caused by sea snake venom and improved survival rate of mice injected
with snake venom (Okonogi et al., 1979).
The phenolic pterocarpans from a Brazilian root
Cabeca – de – negro used in Amazon to treat snake bite. Negro reverses the effect
of Bothrops atrox venom in
dogs (Nakagawa et al., 1982). Unfortunately the botanical identity of this plant
is not known.
Curcuma longa rhizomes (Manjal;
Zingiberaceae) are used to treat snake bite. Turmerone from
C. longa afforded protection against the lethal effect of the venom
Bothrops jararaca when it
was injected into mice (Ferreira et al., 1992).
Atropa belladona, the deadly nightshade (Solanaceae) protects against
the toxins from the green and black mamba. These venoms increase transmitter
release from cholinergic nerve terminals. Therefore it was suspected that a cholinergic
blocker like atropine reduces its effect. This was proved by in vivo tests
in mice (Lee et al., 1982).
Tests to determine anti – venom activity
The testing of plant extracts for anti - venom activity illustrates
the traditional use of plants in treatment of snake bite.
The variety of activity displayed by different snake venom
systems requires different test systems to investigate inhibitory effects of plant
extracts. Workers studying a particular plant species have to devise and use a range
of experiments or concentrate on the most venomous snakes in the area where the
plant is used. A few studies were carried out where the extracts were given prior
to injection of venom or after administration of venom, which is most analogous
to the case of snake bite.
In vivo tests
to determine anti venom activity
The tests should reproduce the conditions and effects of
envenomization but also be economic, socially acceptable and suitable for a high
throughput of samples.
In vivo animal
The protection of whole animals against a dose of venom by
the plant extracts approximates the field situation closely. This method is impractical
now-a-days because of ethical considerations. Recently mice have been used for the
testing of crude extracts. In most cases, a lethal dose of the venom was mixed with
the varying doses of the plant extract and injected into the animal. Later the survival
rate with and without extracts was determined and any significant decrease in mortality
was taken to imply protection due to deactivation of the venom by compounds present
in the plant. A few studies were carried out where the plant extract was given prior
to injection of the venom or after administration of the venom, which is most analogous
to case of snake bite.
Testing using isolated organ preparations
The use of isolated tissue for testing of biological activity
does not require large doses or long periods of experiments using whole animals.
If the effects produced can be removed by washing out, the preparation can be re
– used. The
tests consists of measurements on nerve – muscle preparations,
isolated muscles and studies on blood - clotting procedures. The cobra venoms that
impair neuromuscular transmission is experimentally studied using nerve - muscle
preparations from neck of chick (biventer cervicis) and abdomen of the rat (phrenic
Indirect stimulation of these preparations is inhibited by
the venoms. Plant extracts containing anti – venom activity may consequently reverse
these inhibitory effects. This was demonstrated with
Curcuma longa extract against the neurotoxin from Naja
naja siamensis (Cherdchu et al., 1978; Cherdchu and Karlsson, 1983).
The isolated rat uterus was used to demonstrate the decrease in response to bradykinin
released by the venom of Bothrops in the presence of
Mandevilla velutina (an African plant) extract (Apocynaceae).
Another use of isolated tissue was described in a test for
agents protective against the myotoxins of crotalid venom (Mors et al., 1989). The
rate of release of creatinine kinase enzyme from superfused limb muscles was measured.
The venom causes loss of the enzyme due to damage to the sarcoplasmic membrane and
therefore, a high rate of release. This was considerably reduced by incorporating
an aqueous extract of
Eclipta prostrate (Asteraceae) in to the superfusion medium (Mors
et al., 1989).
The in vitro systems were devised to study the
inhibition of clotting mechanism of blood by plant extracts. Bothrops species cause haemorrhage at the point of injection
due to inhibition of the clotting mechanism. The haemorrhagic effect
was quantified by measuring the change in optical density of the skin at the site
of injection in mice and found that E. prostrata
neutralized the effects of Bothrops venom.
Envenomization by the Carpet viper, Echis carinatus
causes rapid intra - arterial clotting of blood, resulting in internal haemorrhage
due to depletion of fibrinogen.
Mucuna pruriens (Naikurana;
Leguminosae) increased the clotting time of blood induced by E. carinatus
Tests using Enzymes
The enzyme – based assays were used for enzyme – inhibition
or enzyme ctivation of large numbers of plant extracts.The potasium salt of gymnemic
acid isolated from Gymnema sylvestre
(Asclepiadaceae) inhibits ATPase from cobra and viper venom (Kini
and Gowda, 1982). Inhibition occurs due to competitive binding between gymnemate
and ATP. Aristolochic acid from Aristolochia species inhibits the action
of phospholipase – A2 enzyme from viper venom responsible for edema formation.
It occurs due to complexation of phospholipase with aristolochic acid (Vishwanath
et al., 1987). Similarly hypolaetin–8–glucoside, a flavanoid from soyabean inhibited
phospholipase A2 enzyme from snake venom (Alcaraz and Hoult, 1985).
In view of the number of deaths caused by snake bite, particularly
where anti venom is not readily accessible, the development of thermostable cheap
remedies suitable for emergency treatment is important. Scientific investigation
into plants traditionally used to treat snake bite are showing results which indicate
the plants may provide the source for individual compound or standardized extract
which could be of benefit in many places where snake bite is a serious public health
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