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Snake venom is adapted saliva that is formed by distinct glands of only certain species of snakes. The gland which secretes the zootoxin is an alteration of the parotid salivary gland of other vertebrates, and is usually located on each side of the head underneath and at the back of the eye, capitalized in a muscular case. It is offered with large alveoli in which the venom is stored before being transported by a vessel to the base of the fang across which it is expelled. Snake venom is a mixture of different enzymes and proteins which many of it not harmless to humans, but some are very toxic. Snake venoms are ordinarily not dangerous once ingested
Snake venom involves enzymes, proteins and substances with a cytotoxic, neurotoxic effect and coagulants:
Phosphodiesterases are used to affect the target's cardiac system to decrease the blood pressure.
Phospholipase A2 lysing the cell membranes of red blood cells leads to hemolysis
Snake venom hinders cholinesterase causes loss of muscle control.
Hyaluronidase enhances permeability of tissue that boosts the rate of incorporation of other enzymes into the target's cells.
Snake venom frequently contains ATPase which promote the hydrolysis of ATP
Amino acid oxidases responsible for the yellow color of the venom of some species
Some are Neurotoxins: Fasciculins Dendrotoxins Î±-neurotoxins
And other is Cytotoxins: Phospholipases Cardiotoxins Haemotoxins
Uses of snake venom :
Snake venom contains molecules with hemostatins (coagulation modifiers) that may be activators or inhibitors of coagulation process and some are basis for hemostasis tests
Such as Prothrombin Activators which are the best considered snake venom hemostatins. They are presently termed according to the taxonomic name of the snake of origin and advanced classification according to their cofactor condition
Less Common Uses:
Thrombin-like enzymes (SVTLE) snake venom is used for fibrinogen breakdown assay and for the fibrinogen dysfunction detection. SVTLE are not repressed by heparin and therefore used for assaying antithrombin in heparin-containing testers. (Snake venom uses)
Effect of Snake Venom on Human Body
When human is bitten with hemotoxic venom by a snake, the venom decrease blood pressure and increase blood clotting. The venom also hits the heart muscle may causing death.
Cytotoxic venom causing death of tissues. Many cytotoxic types of venom also extent through the body increasing permeability of muscle cells.
Neurotoxic venom interrupts brain function and nervous system it produces paralysis or deficiency of muscle control.
Some animals have normal protection to snake venom, and immune bodies can be brought through cautious applications of managed venom; this technique is used to make the anti-venom treatments. (Effect of Snake Venom)
Types of snake venom
As mentioned, snake venom is modified saliva which contains a variety of proteins and enzymes. Not all snake venoms are dangerous to humans as they contain phosphodiesterase, cholinesterase, hyalurinodase, ATPase. The venom is a clear, limpid fluid of a pale straw or amber colour, or it can be greenish, but very rarely and sometimes with a certain amount of suspended matter. The snake venoms that exist are categorized into several types such as hemotoxic venoms, neurotoxic venoms, cytotoxic venoms and myotoxic venoms. These venoms will be discussed in the next few paragraphs.
One of the major families of snake venom is the neurotoxins venoms; which means it's the venom which attacks the central nervous system and brain.
It is subdivided into three groups: Fasciculins, dendrotoxins and Î±-neurotoxins.
Attack cholinergic neurons by destroying acetylcholinesterase.. This causes tetany, which may lead to death.
Snake example:Â Black Mamba
Dendrotoxins inhibit neurotransmissions by blocking the exchange of ions across the neuronal so it destroys the nerves. For example:Â Mambas Snake
Î±-neurotoxins also attack cholinergic neurons they stop the flow of ACh leading to sensation of numbness.
1-Â KraitsÂ use erabutoxin (theÂ Many-banded kraitÂ usesÂ Bungarotoxin)
2-Â CobrasÂ andÂ cobratoxin.
They produce respiratory heart failures and paralysis, the effect range between mild seizures to even death.Â Snakes that secrets this venom are: Cobras snakes mambas snakes Â sea snakes kraits coral snakes
TheÂ king cobras (ophiophagus hannah) are the most eminent transporters of this venom. Neurotoxic venom is basically destroying nerves. Therefore, victim faces difficulties in speech and swallowing, salivating, breathing difficulty, and may respiratory arrests, convulsions. Mild indications are tunnel vision, dizziness, blurred vision and sweating increase. This venom result in fast deterioration of the synaptic nerves and blockage of nerve impulses from the brain to the muscles.
Phospholipase is an enzyme that transmutes the phospholipid molecule into a lysophospholipid that fixes fat in the cell membrane. Therefore water streams into the cell and terminates it which called necrosis.
example: The Japanese Habu snakes
They attach to particular sites on muscle cells causing depolarisation. For illustration the heart muscle: the heart will beat intermittently and will cause loss. Example:Â King CobraÂ
The toxin abolishes red blood cells this is called haemolysis. it is very slow venom it will not destroy a human
Example: members ofÂ NajaÂ genus e.g. Puff adders (bitis arietans)
This is mild venom that causes localized symptoms destroying blood vessels, tissues and cells. The symptoms seen in 10-15 minutes after the snake bites are: localized pain severe swelling bleeding red blisters blue spotting because of restricted blood circulation
If the victim not treated in four hours he will needs elimination.
They are toxins that destroy red blood cells, disruptÂ bloodÂ clotting, and/or causeÂ organÂ degeneration and generalizedÂ tissuedamage.
Such as venom of 'bothrops moojeni' snakes called the Brazillian lancehead snakes. This venom cause necrosis of muscul its indications are:
jaw, neck, trunk and limbs stiffness
Severe pain in movement
loss of breath
Blackish brown urine discharge.
In the very later stages the muscle proteins arrive to the blood result in kidney failure which is the reason for the urine dark coloration.
Signs & symptoms of snake venom:
There is a variable symptom of snake venom poisoning, depending on the following criteria:
Snake size and species.
The quantity and degree of toxicity of the injected venom.
The location of bite (As it is far away from the head and trunk, it will be less dangerous)
The age of the person (since very old and very young people are in much more risk)
The person with medical problems.
Most pit vipers Bites cause pain immediately and usually within 20 to 30 minutes redness and swelling will occur. This bite can affect the whole leg or arm within hours. When the rattlesnake bites, it causes feeling of tingling and numbness in fingers or toes or around the mouth, also it causes metallic taste in the mouth.
There are other symptoms including: Fever, chills, sweating, general weakness, confusion, anxiety, nausea and vomiting. Terror rather than venom itself causes some of these symptoms. After Mojave rattlesnake bites breathing difficulties can be developed. Also people could get a dry mouth, a headache, blurred vision, and drooping eyelids.
In case of moderate or severe pit viper poisoning usually leads to bruise of the skin after 3 to 6 hours of the bite. The area surrounding the bite appears discolored, tight and it may contain bloody blisters. Unless treatment occurs, tissue of the bite could be destroyed. Bleeding gums may occur, and blood may be present in the person's vomit, stools, and urine.
Coral Snakes: its bite may cause little or no rapidly pain and swelling. Severe symptoms may occur after several hours. The skin surrounding the bite could be tingle, and muscles almost become weak. Sometimes severe general weakness and Muscle incoordination occur. Other symptoms may include drowsinss, confusion, increase saliva production, blurred vision, double vision, and difficulties in swallowing & speech. Also breathing problems may be present.
Management of snake venom toxicity:
Self-Care at Home:
The patient needs tetanus shot if he has not had one within 5 years.
Examine the wound for dirt or broken teeth.
Person must get away from the snake to stop a second bite as snakes can continue biting and inject venom with continuous bites until they finish venom
Remove squeezing items from the victim (like rings or other jewelry) which could take away blood flow if the bite spot swells.
Using mechanical suction is not recommended as it does not remove any considerable amount of venom, and it increase damage of the tissue.
Victim must not cut into the bite spot can cause damage underlying tissues, also increase infection risk, and does not remove venom.
Victim must not use ice because ice does not disable the venom effect and can result in frostbite.
Victim must not use alcohol as alcohol can decrease the pain; however it dilates the local blood vessels that increase absorption of venom.
Victim must not use bandages or narrowing bands these may increase damage of tissue. (Snakebite Treatment)
The lymphatic system is responsible for spread of venoms. This spread can be reduced by the use of a safe bandage over a crumpled pad located over the bitten area. The firm should not be constricted that it stops blood flow. Bandage immediately over the bite area. A pressure bandage should be applied on bite area if it anywhere in body such as trunk.
Special bites as in the head, neck, and back should apply a firm pressure locally if achievable.
Aid breathing, airway and circulation
If respiration failed ventilate with 100% Oxygen
Antivenom is given immediately
Adrenaline intravenous should be given only for serious hypotension or anaphylaxis and cerebral hemorrhage
the patient must be well hydrated to decrease the threat of acute renal failure
Repeat blood tests, ECG, at clinically related breaks
Abnormal coagulation must be corrected; watch for spread intravascular coagulation, heparin contra-indicated in DIC from snake bite
Hypotension must be monitored
Recommended for Tetanus prophylaxis
It is Antivenin Polyvalent equine (ACP) derived antivenin was the standard treatment in emergency departments. (Snakebite Treatment)
Antivenoms are set from horse serum. The anaphylaxis risk is low but is increased in people who exposure to horses, horsey tetanus vaccines, and allergic history.
It is recommended to pre-treatment with non-sedating anti-histamine (promethazine), subcutaneous, and intravenous steroids (hydrocortisone). (Chris Thompson)
Antivenin is administered either through the veins or injected into muscle and works by neutralizing snake venom that has entered the body (Vincent Iannelli)
Crotalidae polyvalent immune FAB (ovine):
Mixed monospecific used as Crotalid bites antivenom. Accustomed to neutralize snakebite toxins it decrease tissue damage and need for fasciotomy deprived of allergic effects. (Brian James Daley)
Antibiotics are given in hospital for severe conditions. Though, antibiotic prophylaxis is suggested such as Ceftriaxone (Rocephin) a Third-generation cephalosporin has wide-spectrum gram-negative action, it hinders bacterial growth by binding to penicillin-binding proteins. (Brian James Daley)
Emergency Department Care:
1-Treatment consists of revising the ABCs and assessing the patient for marks of shock such as:
Dry pale skin Mental status changes
2-To decide the need for antivenin in victims envenomation grading is classified as:
Characterized by there is no systemic toxicity signs, edema, local pain and laboratory values are normal.
Serious local pain
Edema more than 12 inches nearby the wound
Systemic toxicity involving nausea and vomiting
Alterations in laboratory values such as the decrease in hematocrit and platelet count
Characterized by: generalized petechiae
Ecchymosis (subcutaneous purpura larger than 1 centimeter or a hematoma)
Sputum with blood, hypotension, renal dysfunction, and abnormal results significant for consumptive coagulopathy.
3- Antivenin is given for patient that exhibits within 12 hours of the bite in spite of local or systemic symptoms. Neurotoxicity may progress unexpectedly and causes respiratory failure. (Brian James Daley)
4- antigen-binding fragment antivenom (FabAV) aids regulate local tissue effects and hemotoxicity, insistent antivenom treatment does not usually improve effects of neurotoxicity such as myokymia (which is impulsive, sufficient fascicular contractions of muscle without atrophy. The physician must keep continuous checking of myokymia patients mainly of the chest, diaphragm and shoulders to avoid progress of respiratory failure. (Brian James Daley)
5- Surgical treatment aims on the site of injury:
Fasciotomy is specified only for patients with raised partition pressure.
Liberal checking of compartment pressure is necessary. If not accessible, apply the physical seal of compartment hypertension, accompanied by distal pallor, paresthesia, or for the clinical valuation. Injury of tissue after compartment condition is not revocable but can be prevented. (Brian James Daley)