SNAKE BITE

by

Dr. Rizwan Saeed

SCIENTIFIC CLASSIFICATION

Kingdom: Animalia

Phylum: Chordata

Subphylum: Vertebrata

Class: Reptilia

Order: Squamata

Suborder: Serpentes /ophedia (venemous)Linnaeus, 1758

Snakes are elongate legless carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears.

Snake bite is primarily a problem of the poorer rural populations farming activities. Poor access to health services fail to reach hospital in time. Hospital statistics on snakebites therefore

underestimate the true burden. In addition to mortality, some snakebite

victims survive with permanent physical squeal due to local tissue necrosis and, sometimes psychological squeal.

Because most victims are young, the economic impact of snakebite can be considerable.

•Living snakes are found on every continent except Antarctica. •15 families •456 genera • over 2,900 species. • range in size from the tiny, 10 cm long thread snake to pythons and anacondas of up to 7.6 metres (25 ft) in length. •Most species are non-venomous and those that have venom use it primarily to kill and subdue prey rather than self-defense. •Some possess venom potent enough to cause painful injury or death to humans.

EVOLUTION

150 million-year-old specimens, readily identifiable as snakes, yet with lizard-like skeletal structures, have been uncovered in South America and Africa. There is consensus, on the basis of comparative anatomy, that snakes descended from lizards.

Fossil evidence suggests that snakes may have evolved from burrowing lizards

VENOM

The term poisonous snake is mostly incorrect—poison is inhaled or ingested whereas venom is injected

Vipera berus, one fang in glove with a small venom stain, the other still in placeCobras, vipers, and closely related species use venom to immobilize or kill their prey. The venom is modified saliva, delivered through fangs

•DRY BITE

The standard way of estimating the strength of any toxin is to inject a thin solution into standard size laboratory mice, to establish a LD50 dose, i.e. a dose that on average will kill half of the mice in 24 hours

Snake venomscomplex mixtures of proteins and are stored in poison glands at the back of the head. •These proteins can potentially be a mix of

• neurotoxins (which attack the nervous system),

• hemotoxins (which attack the circulatory system),

• Cytotoxins (cell), • bungarotoxins(NEUROTOXIN PROTEINS-KRAITS) and many other toxins that affect the body in different ways.

Almost all snake venom contains hyaluronidase, an enzyme that ensures rapid diffusion of the venom

SNAKE BITE

The most common symptoms of all snakebites are

panic, fear and emotional instability, which may cause symptoms such as

nausea and vomiting, diarrhea, vertigo, fainting, tachycardia, and cold, clammy skin. Television, literature, and folklore are in

part responsible for the hype surrounding snakebites, and a victim may have unwarranted thoughts of imminent death.

SEQULAE OF SNAKE BITE NO EFFECT PSYCHOGENIC EFFECT ENVENOMATION NEUROTOXIC SEQULAE MYOTOXIC EFFECTS SEQULAE OF WRONG INDIGENOUS

PROCEDURES OTHER COMPLICATIONS

COMPLICATIONS OF TOURNIQUET COMPLICATIONS OF INCISIONS WOUND SEPSIS POSSIBLE HAZARDS OF ANTIVENIN

LOCAL EFFECT

HAEMOTOXIC

i) cytotoxins causing local swelling and tissue damage,

ii) haemorrhagins which disturb the integrity of blood vessels,

iii) compounds which lead to incoagulable blood,

iv) neurotoxins causing in neurotoxicity

v) myotoxins which cause muscle breakdown

Dry snakebites,

Those inflicted by a non-venomous species, are still able to cause severe injury to the victim.

a snakebite which is not treated properly may become infected the bite may cause anaphylaxis in certain people, and the snake's saliva and fangs may harbor many dangerous microbial contaminants, including Clostridium tetani.

If neglected, an infection may spread and potentially kill the victim.

INOCULATION / INJECTION BY SNAKE

ENTERS SURROUNDING TISSUE

CAPILLARRY ABSORPTION

LYMPHATIC

BLOOD VESSELS

TARGET ORGANS SYSTEMIC EFFECT

RECOVERY

DEATH

• AUTO-PHARMACOLOGICAL MANIFESTATION

• DIRECT VENOM ACTION

Most snakebites, whether by a venomous snake or not, will have some type of local effect.

In over 90% of cases 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.

Other common initial symptoms of pit viper bites include lethargy, weakness, nausea, and vomiting. Symptoms may become more life-threatening over time, developing into hypotension, tachypnea, severe tachycardia, altered sensorium, and respiratory failure

Australian Elapids , Viper

coagulopathy

Cobras, Kraits, Mambas, Sea

snakesNeurotoxicity

Victim not treatedMay die of

Respiratory failure

necrosis of muscle tissue Muscle tissue will begin to die

throughout the body, a condition known as rhabdomyolysis.

Dead muscle cells may even clog the kidney which filters out proteins. This, coupled with hypotension, can lead to acute renal failure, and, if left untreated, eventually death

Interestingly, bites caused by the rattlesnake, coral snake, and the speckled rattlesnake reportedly cause little or no pain despite being serious injuries.

Victims may also describe a "rubbery," "minty," or "metallic" taste if bitten by certain species of rattlesnake.

Spitting cobras and rinkhalses can spit venom in their victims' eyes. This results in immediate pain, ophthalmoparesis, and sometimes blindness

•Snakes do not ordinarily prey on humans and most will not attack humans unless the snake is startled or injured, preferring instead to avoid contact. •non-venomous snakes are usually not a threat to humans. venomous snakes present far greater hazard to humans

•Snakes are most likely to bite when they feel threatened, are startled, provoked, or have no means of escape when cornered

DEATH WITH SNAKE BITE

Documented deaths resulting from snake bites are uncommon. Non-fatal bites from venomous snakes may result in the need for amputation of a limb or part thereof. Of the roughly 725 species of venomous snakes worldwide, only 250 are able to kill a human with one bite.

TREATMENT The treatment for a snakebite is as variable as the bite itself. The

most common and effective method is through antivenom, a serum made from the venom of the snake.

Some antivenom is species specific (monovalent) while some is made for use with multiple species in mind (polyvalent).

In the United States for example, all species of venomous snakes are pit vipers, with the exception of the coral snake.

To produce antivenin, a mixture of the venoms of the different species of rattlesnakes, copperheads, and cottonmouths is injected into the body of a horse in ever-increasing dosages until the horse is immunized. Blood is then extracted from the immunized horse and freeze-dried. It is reconstituted with sterile water and becomes antivenin. For this reason, people who are allergic to horses cannot be treated using antivenin.

Antivenin for the more dangerous species (such as mambas, taipans, and cobras) is made in a similar manner in India, South Africa, and Australia with the exception being that those antivenins are species-specific.

Keep the victim calm, restrict movement. •  The limb, which has been affected by the bite,

should be immobilized with splint and be kept below the level of the heart. A compression bandage (not tight) should cover the entire limb with the splint.

•  Assure the victim and do not let him panic. When under panic, it will enhance heart rate and would circulate the venom faster in the body.

•  Remove any rings or constricting items; the affected area may swell.

•  A snakebite victim is under tremendous psychological stress. It is necessary to keep the patient warm. However, no alcohol/hot beverages should be given. The patient should not be allowed to exert himself in any manner.

•  DO NOT COVER THE BITE AREA AND PUNCTURE MARKS. The wound should be gently cleaned with antiseptic.

•  Try to aspirate the venom out of the puncture marks with standard suction devices. It has been identified that a suction more than 270 mmHg can initiate the flow from the puncture marks. Suction instruments often are included in commercial snakebite kits.  But, the suction should be applied within 5 minutes of the bite.

•  The only remedy for venomous snakebite is the anti-venom serum, which is available at most government hospitals and public health centers. Some private nursing homes have also started stocking it and treat snakebite cases.

Snake trappingThe tribals of "Irulas" from Andhra Pradesh and Tamil Nadu in India have been hunter-gatherers in the hot dry plains forests and have practiced this art for generations. They have a vast knowledge of snakes in the field. Irulas generally catch the snakes with the help of a simple stick•SNAKE SKIN•SNAKE VENOM

PETS : BALL PYTHON & CORN SNAKE

SYMBOLISM

Medusa by 16th Century Italian artist Caravaggio

Rod of Asclepius, in which the snakes, through ecdysis, symbolize healing.

HISTORY / RELEGION•In Egyptian history, the snake occupies a primary role with the Nile cobra adorning the crown of the pharaoh in ancient times. It was worshipped as one of the gods and was also used for sinister purposes: murder of an adversary and ritual suicide (Cleopatra).•The snake is one of the 12 celestial animals of Chinese Zodiac, in the Chinese calendar.

•The cobra is seen on the neck of Shiva and Vishnu is depicted often as sleeping on a seven-headed snake or within the coils of a serpent

SNAKEBITES Poisonous snakes in the U.S.

Rattlesnake Copperhead Water moccasin Coral snake

PIT VIPERS

Rattlesnake Copperhead Water moccasin

Characteristics: Flat heads that are wider than their necks

(triangular) “Cat eyes” (elliptical) Heat sensitive “pit” between the eye and

nostril on each side of the head

PIT VIPER BITES: SIGNS AND SYMPTOMS

Severe burning/ fang marks Swelling (occurs in 5 minutes and can

involve entire extremity) Mark extent of swelling on body

6-10 hours later: potential discoloration and blood filled blisters

CORAL SNAKE BITES

Most venomous, but rarely bites Red, yellow and black band

Every other band is yellow

Red on yellow, kill a fellow. Red on black, venom lack.

Chews venom into the body

Cobra viper

1 Venom is neurotixic venom is vasculotoxic

2 Injects almost all venom Injects little venom

3 Local symptoms are mildIntense local pain and cellulitis

4 Effects are mainly on CNS Effects are mainly on CVS

5 Lay eggs Give birth to living ones

6 Pupils are circular Pupils are elliptical

7head and neck of same width

Head usually with small scales & neck narrow

SNAKE BITES: WHAT TO DO (CONTROVERSIAL BUT GENERALLY RECOMMENDED)

Pit Viper Get away from snake / may re-strike

Can strike ½ the length of their body A decapitated head can react for 20 more minutes

Have victim lie down and stay calm Do not move victim unless absolutely

necessary Keep bitten area immobile and below the

level of the heart Call 1122 Wash area with soap and water

SNAKE BITES: WHAT TO DO #2

If more than 1 hour from medical facility, use “extractor” within 3 minutes and left on for 30 minutes (pit vipers only) (up to 30% of venom may be

removed) Seek medical attention

immediately Anti-venom available only at

hospitals Same anti-venom used no matter

type of snake Must be given within 4 hours of the

bite

Icing is generally not helpful “Cut and suck method” Increases risk of infection No constriction bands

gangrene (bite on local woman)

Old style snake bite kit that should NOT be used

Application of a tourniquet to the bitten limb is generally not recommended. There is no convincing evidence that it is an effective first aid tool as ordinarily applied. Uninformed tourniquet use is dangerous, since reducing or cutting off circulation can lead to gangrene, which can be fatalCutting open the bitten area, an action often taken prior to suction, is not recommended since it causes further damage and increases the risk of infection.

• No application of potassium permanganate

• Use of electroshock therapy. Although still advocated by some, animal testing has shown this treatment to be useless and potentially dangerous

Until the advent of antivenom, bites from some species of snake were almost universally fatal. Despite huge advances in emergency therapy, antivenom is often still the only effective treatment for envenomation.

The first antivenom was developed in 1895 by French physician Albert Calmette for the treatment of Indian cobra bites

Immunization against snake venom ?

ANTIVENOM

SUPPORTIVE AND SYMPTOMATIC MEASURES

Bed rest Warmth Analgesics and sedatives (codeine, meperedine

avoid morphine d˚ risk of respiratory failure) Shock (fluid electrolyte balance, blood transfusion) Ventilation support (O2 in hypoxia- neurotoxin, tracheotomy)

Antibiotics Tetanus- gas gangrene prophylaxis Heparin (in DIC evidence in hemolysis, Hb drop) Steroids (deals allergic manifestations of antivenin)

CORAL SNAKE BITES: WHAT TO DO

Coral Snake Use same methods except:

Do not use “extractor” Apply mild pressure over the bite site and wrap entire limb with an ace bandage

No ice is necessary

NON-POISONOUS BITES Horse shoe shaped tooth

marks May be painful but no systemic

reactions What To Do?

Minor wound treatment If in doubt, go to hospital or call

Dr.

PREVENTION

Sign at Sylvan Rodriguez Park in Houston, Texas warning of the presence of snakes

SNAKE BITE PREVENTION

Use caution around wood piles, rock crevices etc. Watch where you step Do not reach into holes or hidden ledges Wear boots (50%BITES BELOW KNEE), long pants,

long sleeved shirts Don’t sit or step over logs without checking it out Use a walking stick, Torches When camping, keep tent zipped at all times (float

trip) (child sat on snake) Take a friend along Stay out of tall grass Leave snakes alone Public education (first aid management)

PREVENTION (CONT..) 1) Any unknown snake is potentially dangerous; do not play,

avoid any contact with any snake including those of small size, baby, lethargic, dead. A cut off head can keep poisonous activities for several minutes. Make yourself familiar with the description of poisonous snakes in the place where you live.

2) Attention!!! Use torchlight at night – all local poisonous snakes are active in the evening and at night. Pay more attention in the forest, close to bushes, tall plants, etc.

3) Snakes usually don't bite you without alarm: - Cobra – lifts vertically front part of the body (1/3), opens

hood, makes hiss, rushes to the aim. - Vipers - make a spiral from a tail, bend like zigzag front

part of the body, and make a strong hiss. 4) If you meet a snake, go back slowly, don't do sudden

movements, do not turn your back to the snake, do not run, and give the possibility for a snake to go away

Reassurance and immobilization of the affected limb with prompt transfer to a medical facility are the cornerstones of the immediate care of snakebite.

Pressure immobilization is used for some elapid species. The mainstay of treatment of snakebite is the infusion of an appropriate antivenom. Snake venoms are diverse, and therefore the efficacy of antivenoms is geographically and biologically restricted, meaning that a large number of antivenoms have been developed for use in different settings

Antivenoms are manufactured by immunizing horse or sheep with venom from a particular species and then processing the serum from the animal. Both monospecific and polyspecific antivenoms are available;

monospecific antivenoms are produced using the venom of a single species, whereas polyspecific antivenoms are produced against the venoms of several species that are prevalent in a geographic region.

In the rural tropics, victims are often bitten in an agricultural field or jungle, and in many instances the biting species is not identified. In such situations, treatment with polyspecific rather than monospecific antivenoms may be more appropriate

SNAKES: ADDITIONAL INFORMATION

Poor vision, especially when shedding Prime time for crawling snakes in this area:

August Baby snakes have stronger venom Snakes just out of hibernation have stronger

venom Many organizations, including the

American Medical Association and

American Red Cross, recommend washing the bite with soap and water. However, do not attempt to clean the area with any type of chemical

To train farmers, students and traditional healers in first-aid for snakebite

To discourage dependency on traditional healers

To familiarize people with venomous snake

To know the impact of snakebite first-aid education.

We need to :

Pressure immobilization

EPIDEMIOLOGYWorldwide, snakebites occur most frequently in the summer season when snakes are active and humans are outdoors. Agricultural and tropical regions report more snakebites than anywhere else. Victims are typically male and between 17 and 27 years of age. Children and the elderly are most likely to dieHIGHEST SNAKE BITE DEATHS IN SIRILANKA =33000 (2008)

COBRA MAP PAKISTAN

DEATH / 100,000 DUE TO SNAKE BITE

•PAKISTAN = 1.90•INDIA = 5.40•BURMA = 15.40•TRINIDAD & TOBAGO = 2.49

(2007)

•Most snakebites are caused by non-venomous snakes. Of the roughly 3,000 known species of snake found worldwide, only 15 % are considered dangerous to humans

•Since reporting is not mandatory in many regions of the world, snakebites often go unreported.

CONCLUSIONsnakebite mainly affects the rural men of developing countries. Availability of anti-venom at primary healthcare centre's and rapid transportation facilities may change the morbidity associated with snakebites.Early administration of the polyvalent anti-venom has reduced morbidity and mortality but is associated with anaphylaxis in small group of patients.There is need to educate the rural population about the hazards and treatment of snake bites.randomized controlled trials are needed to investigatethe issue of rationale of anti-venom treatment.

REMEMBER

 

•  As a common man, one should know how to administer proper first-aid to a snakebite victim, without losing precious time. •  Never try to assess whether it was venomous snakebite or not. As a layman one should treat every snakebite as venomous snakebite, as some snake venom (like that of common krait) does not show immediate effect even in the case of a serious bite, it is wise to rush to a hospital. •  Even if in doubt about whether it is a snakebite or not, do the first-aid and rush the victim to the nearest hospital. •  Educate your children that putting one's hand into any kind of burrow could be dangerous.  

•  Never get into a dark bathroom; first switch on a light and then see around you before you enter. •  Not all bites from venomous snakes lead to death; many venomous snakes (and as many as 85% of snakes are non venomous) deliver only a dry bite to humans. Even in the case of a full bite, with appropriate first-aid, care and treatment a snake bite victim can fully recover. Very few venomous snakebites are fatal. Just as every mosquito bite does not cause malaria, so every snakebite does not cause death. •  No attempt should be made to kill the snake to carry it along to the hospital. It would result in delaying the arrival of the patient to the hospital and is potentially dangerous for the person who will attempt killing the snake. Qualified doctor can diagnose observing the patient for clinical symptoms and pathological tests.

All snakes are not venomous – so every snakebite is not going to result in death – it would save people from quacks. And reduce the amount of panic and chaos. Even a venomous bite is not always fatal – because the severity of snakebite depends on many factors like the size of the snake, whether the bite could be completed, whether it was a dry bite or not, the age, physique and affected limb of the victim. First Aid would enable a person to buy more time to reach medical aid on time. The only cure which is available is anti-venom serum injection and not quacks. First Aid - if not done properly could cause more harm than benefit.

#1 - Taipans (genus Oxyuranus)

#2 - Krait (Bungarus coeruleus)

TOP FIVE DEADLIEST SNAKES

#3 - Philippine Cobra (Naja naja philippinensis)

#4 - King cobra (Ophiophagus hannah)

#5 - Russell's viper (Daboia russelli)

THANK YOU