Common Indian Venomous Snakes .pptx

PPT describes detail regarding Poisonous snakes in India along with features for Identification with pictures, Difference between Venomous and Non-venomous snakes and Signs and Symptoms of bite, Management of bite and Medicolegal Aspects.

1. SNAKES ( ophidia ) (Irritant organic animal poison)

2. In the world, there are about 2500 species of snakes. In India, there are about 250 species, out of which about 50 species are poisonous. The common poisonous snakes in India are Cobra ( naja naja ), King Cobra ( ophiophagus hannah ), Krait ( bungarus caeruleus ), Banded krait ( Bungarus fasciatus ), Russell's viper ( daboia ruselli ), Saw-scaled viper ( echis carinatae ) and Sea-snakes, most common being krait. Snakes are found all over the world except in Greenland, Ireland, Iceland, Jamaica and New Zealand. There are no vipers in America. Snakes have an elongated body and a short tail, that is the part behind vent i.e. the opening for intestine and genitourinary system.

3. There are no limbs. Eyelids being fused appear to be absent. The body is covered by scales and the head has 2 eyes, 2 nostrils, no external ear and a distensible mouth. Tongue is forked and helps as a sense organ. Teeth are thin, directed backwards and the upper marginal teeth are long and canalised and are known as fangs. Fangs can be replaced in 3-6 weeks when broken. The fangs in poisonous snakes are connected by a duct to the venom glands ( racemose glands) i.e. modified parotid salivary glands. Colubrine are oviparous, while vipers are viviparous. For medicolegal purposes, snakes are classified as : 1) Poisonous 2) Non poisonous

4. The diff. bet n poisonous and non poisonous snakes : Poisonous Non poisonous 1) Body scales i.e. on anterior side are large and cover the whole width. 1) They are small or moderate. 2)Head scales are small e.g. in Vipers. However there are few exceptions - a) In pit viper, there is a greenish pit between eye and nostril. b) In Cobra and King-cobra, the third labial is large and touches the eye. c) In krait, the central row of scales on the back is large, and the 4th infralabial is very large. 2 ) The head scales are large 3) Fangs are present and they are canalised (in vipers) or grooved in colubrine) 3) Usually, fangs are absent. If present, they are short and solid. 4) Tail is compressed 4) Not so. 5) Generally noctural 5) Not so. 6) Bite - mark shows 2 fang marks and there may be present the marks due to other small teeth (in colubrine). 6) No fang marks. 7 ) Saliva toxic 7) Non toxic

5. CLASSIFICATION OF POISONOUS SNAKES: 1) Colubridae : Elapidae :- Cobra and krait; pupil is round . Hydrophiidae :- Sea Snakes, pupil is round. 2) Viperidae - includes vipers, pupil is vertical On the basis of poison, the snakes are Classified as : 1) Elapids - Neurotoxic - Fangs are 4-6 mm. 2) Vipers - Vasculotoxic - Fangs are 12-15 mm, mobile. 3) Sea snakes - Myotoxic - Fangs are 2-4 mm.

6. Vipers - Fangs

7. POISONOUS SNAKES IN INDIA 1) Cobra (Mar & Guj - Nag ): It is usually black, 5-6 feet, has a hood on dorsal side on which there is a single or double spectacle mark or an oval spot surrounded by half circle. On ventral side are 2 black spots. Head scales are large & third supralabial is big. The colour is brown or dark. It prefers populated areas.

8. 2) King - Cobra (Mar- Nagraj ) : Is 6-18 feet, there is no mark on hood, prefers forests. The colour may be yellow, green, brown or black and has yellowish or white cross bands on the body.

9. 3) Common Krait (Mar- Maniyar , Guj - Kalo taro ): Is usually steel-black, 3-5 feet. It prefers area in or near the houses. The head shields are large, there are four infralabial shields and scales in central row on back are large and hexagonal. There are single or double white arches across the back. Nocturnal in habit.

10. 4) Banded krait (Mar- Pattere Maniyar ) Is 5-7 feet and has 2" broad alternate black and yellow bands on the body (rarely dark brown and light brown), in addition to features as in common krait. Head : Black mark Triangular Back Rounded Tail tip

11. 5) Pit-Viper : Is 1-3 feet and has a heat sensing green pit between each eye and nostril. Usually found in hills.

12. 6) Russels Viper : (Mar- Ghonas , daboia , Guj - Chitalo , Khadchitalo ) : Is 4-5 ft. long. Head is flat, triangular and has white, V shaped mark, pointing forwards. Body wide and has 3 rows of diamond shaped marks. It produces loud hissing sound when about to attack.

13. 7) Saw-scaled viper : ( Mar- Fursa : Guj - Tarachha ) Is 1-1.5 ft. usually brown, head is triangular and having a wide mark which resembles an arrow or of each scale are like a saw - hence the name saw scaled viper. These rough scales produce rustling sound when snake moves.

14. 8) Sea Snakes : Have a snout and tail is fin like. They are black, greenish black or bluish black with or without bands. 20 types are seen in Indian waters, all of them being poisonous.

15. SNAKE – VENOM : Snake venom ( toxalbumin ) is heterogeneous mixture of proteins produced and stored in the specialised salivary glands. The freshly secreted venom is transparent, pale liquid and on drying it becomes yellowish, opaque, granular powder which remains active for many years. The proteins in the venom are in the form of enzymes, peptides and polypeptides. The enzymes are Proteinases , - Ribonuclease , Hydrolases , - Deoxyribonuclease Transaminase , - Phosphomonoesterase , Hyaluronidase , - Phosphodiesterases Phospholipase A, B, C & D, - 5-nucleotidase,

16. Collection of Snake venoum :

17. ATPase , - Coagulases Alkaline phosphatase , - Agglutinins, Acid phosphatase , - Fibrinolysin Cholinesterases - Haemolysin etc. In elapids there are neurotoxins , which are polypeptides. They block the neuromuscular junction and thus decrease the output of acetyl choline . The marked toxicity is on CNS, respiration and heart. The viperine venom is mainly haemolytic , hemorrhagic and necrotic. It causes intravascular haemolysis and depression of coagulation mechanism. The sea snake venom is myotoxic . It leads to muscle pain, myoglobinuria and hyperkalemia .

18. Proteolytic enzymes : Cause digestion and destruction of tissue proteins. Hyaluronidase : Helps spread of venom. Phospholipase : Causes Hemorrhaging : Causes spontaneous bleeding. Haemolysin Causes lysis of RBC Leukocyten : Causes lysis of WBC Cytolysin : Causes damage of internal viscera. Rhabdomyolysis : Causes necrosis of muscles. Proteases Causes dissolution of blood vessels. Fibrinolysin Breaks down fibrin and causes lysis of clot.

19. SIGNS AND SYMPTOMS : The snake venom on ingestion is non poisonous since it can be digested. Poisoning occurs due to snake bite, injection of venom or absorption through abraded skin or mucous membrane. The manifestations depend upon age, size and health of snake and site of bite. Sometimes sudden death may occur due to fright. The snake venom can be detected by radioimmunoassay (RIA) or enzyme immuno assay (EIA).

20. 1) ELAPIDS A) LOCAL MANIFESTATIONS: They are mild in the form of burning and triple response (i.e. redness, swelling, and inflammation) at the site of bite. B) SYSTEMIC : Neurotoxic, vomiting, dizziness, lethargy, salivation, extraocular muscle paralysis, ptosis , difficulty in speaking and swallowing, muscle weakness and pain, staggering, spreading paralysis (ascending from lower limbs), convulsions and death. (No convulsions in Krait)

21. II) VIPERS : A) LOCAL MANIFESTATIONS : Intense pain, swelling, irritation, cellulitis , cyanosis, oozing of blood serum and formation of blisters containing sero -sanguineous or rarely serous fluid. After 1 week - necrosis develops at the site. Absence of oozing of blood serum indicates that venom has not been injected in wound (failure of clotting is due to low levels of fibrinogen) B) SYSTEMIC : Vasculotoxic , vomiting, unconsciousness, intravascular hemolysis leading to hemoglobinuria , Petechial haemorrhages on various mucous membranes and organs, bleeding from body orifices and hypotension.

22. III) SEA SNAKES A) LOCAL MANIFESTATIONS : The prick is initially painful but is soon painless. B) SYSTEMIC : Myotoxic , vomiting, muscular pain, muscle stiffness, collapse, myoglobinuria , hyperkalemia and increased serum transaminase levels. LABORATORY FINDINGS : 1) RIA/EIA/ELISA To detect antigen 2) Blood Leukocytosis , thrombocyto-paenia , haemolysis, prolonged clotting and prothrombin time, hypofibrinogenemia 3) Metabolic - Acidosis, hyperkalemia 4) Urine :- Presence of Hb , albumin, blood & azotemia .

23. FATAL DOSE: FATAL PERIOD: - In Colubrine -: 20 min. to 6 hrs. - In Viperine -: 2 to 4 days. Snake Fatal Dose Amount Injected per bite 1) Cobra 12 mg of dried venom 200-350 mg. 2) Krait 6 mg. -" 20-22 mg 3) Russels viper 15 mg. -" 150-200 mg 4) Saw scaled viper 8 mg. -" 25 mg

24. TREATMENT :- The treatment includes : 1) To allay fear and anxiety. 2) Prevention of spread of venom. 3) Use of antivenom serum. 4) Treatment of absorbed venom 5) Symptomatic and general treatment 1) ALLAYING FEAR AND ANXIETY : The commonest cause of mortality in snake bite is fear and tension. Every patient should be reassured that all snakes are not poisonous and that the poisonous snake bite can be treated.

25. 2) PREVENTION OF SPREAD OF VENOM : a) Clean the bite area with soap and water or saline. b) Washing with KMnO 4 solution neutralises the poison. c) Give a 0.5 cm deep incision through the fang marks and suck the area with mouth, breast pump or suction machine (In case of any ulcer in the mouth or upper GIT, sucking by mouth should not be done). d) Apply tourniquet proximal to the site of bite (if bite is on extremity) preferably two tourniquets applied, out of which one should be preferably on a single bone. (The tourniquet should be released for 20-30 sec. every 20-30min. to avoid gangrene and it should be tight enough to occlude lymphatics but not veins). e) Immobilise the part since it prevents spread of venom and relieves pain.

26. f) Local heparin infiltration in vipers and carbolic soap solution in elapids is useful. g) According to some, local emetine or gold chloride injection, at the site of bite helps to prevent the spread. 3) USE OF ANTIVENOM SERUM : ( Antivenom therapy) To counteract the toxic effects of snake venom, anti snake venom serum is used. It should be started before releasing the tourniquet. (It is prepared by injecting the snake venom into horse and collecting the antibodies). The anti-snake venom serum may be monovalent i.e. effective against a specific snake (not available in India) or polyvalent which is effective against Cobra, Krait, Russell's viper and Saw-scaled viper.

27. This serum is lyophilised i.e. is freeze dried and is available as granular powder. It is reconstituted by 10 ml of distilled water (Be sure that the solution is clear). The serum remains potent for about 10 years. Since it is a serum, if time and condition of the patient permits then sensitivity test should be done injecting 0.1 ml intradermal . In a person who is not sensitive, 20 ml of the serum is injected, I.V. 5 ml/min and it can be repeated if required. (As per some books the serum should be given 20 ml I.V. 20 ml IM and 20 ml at the site of bite). Local injection is useful in vipers to avoid local gangrene. If a person is sensitive to the serum, he is desensitized by injecting multiple small doses, under cover of adrenaline, antihistaminics and corticosteroids.

28. 4) TREATMENT OF ABSORBED VENOM : a) In elapids : - Alternate 0.6 mg atropine and 0.5 mg neostigmine . - In paralytic cases SC adrenaline and IM calcium chloride b) In Vipers : 1) 30,000 – 40,000 units heparin. 2) 300 - 600 gms fibrinogen. 3) It has been found that a very high voltage i.e. 20,000 – 30,000 volt and very low amperage i.e. 1-2 milli amp. current applied at the site of bite is useful. 5) SYMPTOMATIC AND GENERAL TREATMENT : Use of tetanus toxoid , antibiotics, antihistaminics , analgesics, barbiturates, steroids, blood transfusion, artificial respiration and hemodialysis . - IgG is said to improve coagulopathy

29. MEDICOLEGAL ASPECTS : - Snake bite is usually accidental. Annually about 2 lakh people are bitten by snakes and about 30,000 die. - Suicides are not common. Cleopatra (queen of Egypt) committed suicide by getting herself bitten by a viper. - Sometimes relatives attribute a suicidal or homicidal death to be due to snake bite. - Sometimes snake venom is used as cattle poison ( Venomised banana or rug thrust into rectum). - Snake venom can cross placenta and hence can poison foetus. - Polyvalent antivenom is prepared at - - Haffkine Institute, Mumbai. - Central Research Institute, Kasauli , HP. - King's Institute, Chennai. - Serum Institute, Pune.