What are the other Names for this Condition? (Also known as/Synonyms)

• Common Tiger Snake Bite
• Mainland Island Snake Bite
• Notechis Scutatus Snake Bite

What is Mainland Tiger Snake Bite? (Definition/Background Information)

• The mainland tiger snake (Notechis scutatus) is a common and highly venomous snake that is mostly distributed in the tropical-to-temperate southeastern and southwestern regions of Australia, including on the island of Tasmania. The snake usually inhabits regions around wetlands and waterbodies, such as rivers and swamps, since it mostly preys on frogs
• The snake belongs to the Elapidae family (genus Notechis), which generally includes slender and swift moving snakes. Two distinctly related species of tiger snakes (Notechis scutatus and Notechis ater) including several subspecies are described in various scientific literature:
  • Notechis ater; the black tiger snake
  • Notechis ater ater, also called Krefft’s tiger snake
  • Notechis ater humphreysi, also called Tasmanian tiger snake
  • Notechis ater niger, also called the Peninsular tiger snake
  • Notechis scutatus; the common or mainland tiger snake
  • Notechis scutatus occidentalis, also called the western tiger snake
  • Notechis scutatus scutatus, also called the eastern tiger snake
  • Notechis scutatus serventyi, also called the Chappell Island tiger snake
• It is important to note that there is an ongoing intense debate on tiger snake species and subspecies classifications among the scientific community. However, this is more a matter of taxonomy (classification and nomenclature) and does not in any way change the physical and biological description, behavior, or the very venomous nature of the tiger snakes. In fact, after the eastern brown snake, the tiger snake takes the record for most snake bites in Australia
• This medium-bodied and robustly-built snake can grow to sizes ranging from 4-5 feet; although large sizes, over 6.5 feet in length, have been recorded. The tiger snake has a small flat and wide head, an almost continuous and thick neck, and a short tail. The size and coloration may vary based on the geographical location and subspecies type
• The body of the snake is usually shiny and dark, ranging from black, brown, olive brown, yellow orange, or gray; the sides and belly (and lower jaw) may be yellow cream, light orange or gray white. Most tiger snakes have dark wide bands that run along the body of the snake with white, light brown or even yellow interspaces. In some snakes, no bands are visible, especially in fully-grown adults
• Even though the mainland tiger snake inhabits a variety of terrain, such as dry forests, open woodlands, and grasslands, it is most often found near watercourses including flood plains, coastal lowlands, inland wetlands, swamps and marshes, creeks, and riverine banks. The snake is active during the day (usually early mornings or late evenings), but may prefer to be nocturnal during the hot summer months
• Apart from frogs, the snake feeds on fish and eels, mice and rats, lizards, and even small birds (particularly near coastal areas and islands). The snake usually shelters near dense thickets, in deserted animal burrows, under rocks, and rotting tree stumps. The mainland tiger snake may be found near human habitation and bites involving humans are not very infrequent. The distribution of the snake places it among certain highly populous semi-urban and urban regions (including metropolitan cities) of Australia
• The tiger snake is usually timid and non-aggressive unless sufficiently disturbed; its preliminary reaction is to move away in the face of danger. However, if cornered or surprised, the snake presents a raised and flattened upper body, loosely-coiled posture, with loud hissing, showing a readiness to strike. Any further provocation at this stage will result in a sudden strike; and if it attacks, the snake is known to bite repeatedly
• Mainland Tiger Snake Bite can result in early fatalities due to systemic envenomation (venom injection through a bite), if the condition is left untreated, due to the presence of highly potent neurotoxins, myotoxins, hemotoxins, and other compounds in the venom
• The signs and symptoms of Mainland Tiger Snake Bite have a rapid onset, but may be non-specific and include headaches, sweating, weakness, nausea and vomiting, abdominal pain, and dizziness. Severe widespread symptoms and complications may involve the neurological, cardiovascular, hematological (blood-related), respiratory, and kidney systems
• Early administration of suitable antivenom (or antivenin) is the mainstay of treatment. Apart from this, symptomatic treatment is necessary, which may include the use of vasopressor agents, blood transfusion, and peritoneal dialysis. The prognosis of Mainland Tiger Snake Bite with prompt and effective therapy is usually good

Who gets Mainland Tiger Snake Bite? (Age and Sex Distribution)

• Mainland Tiger Snake Bite may occur to any individual exposed to the snake in the endemic regions
• Individuals of any age and gender are prone to snake bites
• Tiger snakes are found in the following Australian states and islands, including Tasmania:
  • Along coastal Western Australia, from east central to southern corner to south central regions
  • Coastal South Australia, especially Yorke Peninsula (including Kangaroo Island), southwest regions of Eyre Peninsula, and southwest coastal strip to the east of the state
  • Victoria, except for certain west central regions
  • Southern boundary and eastern coastal regions of New South Wales
  • Queensland; in the southeast corner and a few isolated pockets within the state
  • Tasmania and islands in the Bass Strait

What are the Risk Factors for Mainland Tiger Snake Bite? (Predisposing Factors)

The risk factors for Mainland Tiger Snake Bite include the following factors:

• Living or residing in areas where the mainland tiger snake is found; human contact is quite common in the endemic regions
• Having dwellings close to water sources that attract frogs
• Occupational hazard: In some cases, the snake may pose a threat to those working in farmlands, plantations, and herding cattle
• The snakes are good swimmers, thus putting individuals at risk near water bodies
• Wading through marshlands, swampy areas, and walking along river banks
• Walking barefoot or unprotected through open grasslands and woodlands
• Venturing outdoors during the night
• Professional snake catchers
• Wildlife enthusiasts and scientific study groups, who explore the region
• Keeping them as pets
• Handling dead or live mainland tiger snakes; intentionally or accidentally picking up the snake

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Mainland Tiger Snake Bite? (Etiology)

Mainland Tiger Snake Bite takes place when one comes into contact with the venomous mainland tiger snake, usually unintentionally or inadvertently.

• The snake is generally docile and tends to move away when threatened. However, when required, it is not reluctant to hold ground, display warning signs, and then attack
• When cornered or provoked, the snake presents a raised head and upper body striking posture (like a coiled spring), which if ignored can result in a quick and accurate strike. The snake can often inflict multiple bites in a single strike
• Mainland Tiger Snake Bites can cause the injection of a highly potent venom consisting of hemotoxins, pre-synaptic and post-synaptic neurotoxins, and myotoxins into the body

According to scientific literature, the rate of envenomation of the snake is between 40-60%. A lack of treatment or delayed treatment may result in fatalities in about 1 in 2 cases.

What are the Signs and Symptoms of Mainland Tiger Snake Bite?

The signs and symptoms of Mainland Tiger Snake Bite can vary from one individual to another. The signs and symptoms depend on the age (whether child or adult), weight, and overall health status of the individual (whether having an underlying condition or illness). Also, the signs and symptoms vary according to the species/subspecies of tiger snake, venom potency, and amount of venom injected.

The common signs and symptoms of Mainland Tiger Snake Bite that may develop within minutes to a few hours may include:

• Local effects at the bite site:
  • Pain at the bite site
  • Fang marks may be noticeable
  • Swelling and bruising
• In a majority of cases, the bites occur on the legs or hands
• Headaches
• Sweating
• Nausea and vomiting
• Abdominal pain and diarrhea
• Breathing difficulties
• Fainting, dizziness
• Weakness and malaise

Some of the systemic signs and symptoms that may develop in most of the affected individuals may include:

• Low blood pressure
• Destruction of red blood cells (hemolysis)
• Increased white blood cells (leukocytosis)
• Internal hemorrhage and gastrointestinal bleeding may take place:
  • Blood in urine
  • Bleeding from the nose
  • Bleeding from recent wounds and the bite site
  • Mucosal bleeding (seen a few hours after the bite) from the gums, eye, gastrointestinal tract, etc.
  • Anemia due to spontaneous bleeding
• Heart-related abnormalities such as slow or fast ‘resting heart rate’
• Acute kidney injury or kidney failure
• Neurological symptoms are commonly noted; the condition results in severe flaccid paralysis

Note:

• In some cases, the fang marks may not be pronounced or even visible on the skin. Sometimes only small scratch marks or lacerations may be observed. Thus, any contact with a mainland tiger snake merits immediate medical attention
• Severe anxiety may also result in some misleading symptoms of snakebites, such as sweating, fatigue, and shock, even when no bite has taken place (the individual may be imagining), or when it is a dry bite. Nevertheless, even in suspect cases, the presence of any such symptoms requires the attention of a qualified medical professional
• Also, if the individual has been treated using alternative/native medicines, it may present additional confusing symptoms. Thus, it is important to always consult a qualified healthcare provider promptly

How is Mainland Tiger Snake Bite Diagnosed?

Mainland Tiger Snake Bite may be diagnosed using the following tests and exams:

• Complete physical examination with comprehensive evaluation of medical history; a physical examination of the affected site by the physician may be normally sufficient to diagnose a snake bite
• The individual may be asked to provide an account (history) of the events that occurred (what took place and how), if possible
• Assessment of the signs and symptoms exhibited by the individual may be carefully observed
• Blood tests that may include: (many of these tests are repeated over the course of treatment)
  • Complete blood count (CBC) with differential and platelet count
  • White blood cell count
  • Hematocrit blood test: Hematocrit is the proportion of blood that is made up of red blood cells
  • Prothrombin time (PT) and partial thromboplastin time (PTT) tests
  • Fibrinogen blood test
  • Lactate dehydrogenase (LDH) test
  • Serum electrolytes including blood urea nitrogen (BUN) and creatinine levels
  • Arterial blood gas
• Urine test or urinalysis to test for free protein, myoglobin, and hemoglobin levels
• Continuous urine output monitoring is helpful to determine damage to the kidneys, if any
• Electrocardiogram (ECG)
• Kidney function test and liver function test
• Nerve conduction studies and neurological evaluation

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Mainland Tiger Snake Bite?

The complications of Mainland Tiger Snake Bite may include:

• Multiple bites, causing injection of a large quantity of venom
• Blood clotting defects resulting in severe internal bleeding
• Venom-induced consumption coagulopathy (or disseminated intravascular coagulation, DIC) resulting in blood clot formation in the body
• The snake toxin can damage the muscle resulting in muscle breakdown known as rhabdomyolysis. Extensive muscle breakdown can lead to a variety of complications including kidney failure
• Severe shock
• Seizures and coma

Presence of misleading symptoms due to fear and anxiety, which may be also aggravated by those around the individual, such as one’s family members, can sometimes result in inappropriate or over-treatment.

Antivenom reactions:

• Some individuals may develop an allergic reaction, such as anaphylaxis, to the antivenom that may be serious. This may develop within 10 minutes or even after 6 hours, typically starting with itchiness over the scalp and other skin areas
• Life-threatening anaphylactic reactions that require immediate medical treatment may include:
  • Low blood pressure or hypotension
  • Bronchospasm causing narrowing of the airways (bronchi) resulting in breathing difficulties
  • Angioedema: Swelling of skin tissue layers at various locations including the throat, causing speaking and breathing difficulties
• Serum sickness may develop as a complication of antivenom therapy causing fever, nausea, itchy skin, muscle and joint pain, etc. It may develop after 4 days or even 2 weeks (average 7 days) following the administration of antivenom serum

Cardiovascular, hematological, and kidney abnormalities can result in severe complications including death.

How is Mainland Tiger Snake Bite Treated?

All snake bites should be considered as medical emergencies and evaluated by trained medical professionals, as soon as possible; the first 6-8 hours are particularly vital for preventing life-threatening symptoms. Failure to obtain early assessment and management from the highest level of care (available within the community) may potentially result in severe complications and death.

The snake bite can cause severe envenomation and hospitalization is necessary. In many cases, urgent first aid care and support, in the form of compression bandages, limb immobilization, and monitoring of vital signs is necessary and highly-recommended before the patient is hospitalized.

The following measures may be considered in the treatment of Mainland Tiger Snake Bite, based on the medical evaluation of a trained healthcare professional:

• Administration of Ringer's lactate solution (to keep the patient well-hydrated)
• Administration of anti-snake venom (ASV) to neutralize the venom through slow intravenous injection or infusion method
• Address any signs or early allergic reaction: A close observation of the patient is necessary for a minimum of 60 minutes immediately following antivenom administration, to detect early allergic reactions, if any
• Periodic blood and urine tests are undertaken for 12-24 hours or more
• Tetanus vaccination is usually required, if it is not up to date
• The patient is generally admitted and placed in an ICU setting and monitored for at least a day following the abatement of symptoms; the patient has to be rested and kept warm
• Strict bed rest to prevent trauma may be advocated in case of hemostatic abnormalities that arises from a hemotoxic/cytotoxic venom (the venom can result in increased bleeding tendencies leading to substantial blood loss even to minor trauma)
• If necessary, blood and plasma transfusions for severe cases
• Medications to increase blood pressure such as vasopressor drugs and plasma expanders
• Administration of anticholinergic medication for those with low blood pressure causing abnormally slow heart rate (bradycardia). Such anticholinergic medications help increase the heart rate and blood pressure
• Peritoneal dialysis for acute kidney failure
• Providing life support, such as ventilation assistance and treatment for shock, for those with severe symptoms leading to potential organ failure
• Unless infection or tissue necrosis is observed, the administration of prophylactic antibiotics is generally not recommended in snake bites. However, the healthcare provider will determine whether antibiotics administration is necessary or not, based on one’s individual circumstances

Note:

• Consultation with a medical toxicologist is recommended for all cases requiring the administration of anti-snake venom
• Even though antivenom therapy is the key treatment for systemic envenomation; on its own, it may never be adequate enough to completely resolve the condition. Other supportive and symptomatic measures are always necessary to save the patient
• The dose of antivenom does not vary for a child, adult, or even for a pregnant woman, since the snake typically injects the same quantity of venom into an individual
• Gynecological evaluation may be necessary for pregnant women bitten by snakes to evaluate the health of the fetus
• In many instances, the type of venomous snake involved in the bite is unknown; hence, all vital organs and systems should be closely monitored and treated appropriately, as necessary

How can Mainland Tiger Snake Bite be Prevented?

Mainland Tiger Snake Bite may be avoided by:

• Learning to recognize mainland tiger snakes using the following tips:
  • Length of the snake is 4-5 feet or more; uniform and robust body that is mostly dark colored (brown to orange) with cross bands
  • The snake is quick-moving and is active during early mornings; it is a shy reptile that tends to avoid humans/intruders
  • It may be found around waterbodies and wetlands
  • When approached, the snake may present a raised head, neck, and flattened upper body in a curved “S” shaped posture with loud hissing, indicating a willingness to face the threat and strike if necessary
• If you spot a mainland tiger snake, step back slowly and keep a safe distance of at least 10 feet or more (between yourself and the snake)

Outdoors:

• Being alert, if you are outdoors in snake-infested regions, particularly containing dangerous species of snakes
• Avoiding being outdoors at night in forested areas; be careful while camping outdoors
• Avoid tall grassy areas or thick bushes; if you plan to explore the area, use heavy boots and thick pants
• Always step on top of large rocks and fallen trunks; never place one’s foot by the side of big rocks and rotting tree stumps. Some snake species are known to take shelter or warm themselves on the sides, during the day
• Always check before sitting on dead tree logs, stumps, or a pile of rocks; use a stick to stir or probe around the area
• While walking through areas with thick undergrowth, pay attention to the sound of birds or other animals that may warn of potential dangers such as snakes
• While walking outdoors at night, use a flashlight or lamp and make constant noise (singing or talking to others) or stomping sounds that may alert the snake to move away from the region
• While walking through tall grass or undergrowth, try to walk one behind the other in a single file
• Avoid snake-infested regions or even walking on cleared forest paths and roads during nights, immediately after heavy rains that may flush snakes out to the open, due to flooding of their burrows and holes
• Never probe holes on the ground or termite mounds with bare hands or even using small sticks; avoid clearing low-lying bushes using one’s hands
• Carry a snake bite kit, if possible, when traveling through areas containing highly venomous snake species

Residential settlements:

• Keep homes and surrounding areas clean and clear of rubbish or leafy piles, termite mounds, even building materials (like bricks and large stones)
• Cut tall and unkempt grass or low-lying shrubs and bushes around dwelling areas that provides hiding places for snakes and other rodents
• Avoid keeping farm animals and birds (particularly chickens and ducks) and food grain storage yards in, near, or adjacent to the house
• Natural disasters, such as floods and forest fires, are known to drive out snakes and other creatures into homes seeking shelter. Hence, always remain vigilant when returning home following such situations
• Never intentionally run over snakes on the road while on a vehicle (cycle, other 2-wheeler, or 4-wheeler); the injured snake lying on the road may strike other pedestrians, or get entangled in the vehicle and be carried to the parking lot or even inside one’s garage

Occupation-related:

• Avoid collection of firewood at night, especially in lowlight or under moonlight
• Exercise vigilance while working in farms, particularly during the harvest season or after flooding
• Ensure that employers provide adequate protective clothing (gloves, boots, etc.) to those who work in high-risk (for snake bite) occupations such as agriculture or fishing industry

Other points to consider:

• Avoid playing with or teasing snakes such as by touching their tails
• Do not pick up dead snakes - they may be poisonous and still bite through a reflex action
• Do not reach into dark nooks/corners/recesses with your bare hands/foot
• Teach and educate children about the dangers and importance of snakes
• Take steps to educate the members of a community to identify venomous snakes, recognize bite symptoms, and how to avoid encounter with snakes
• Completely avoid any form of native or traditional treatment for snake bites

Both large and small snakes (adults and juveniles) have the potential for severe envenomation; hence, all snake bites should be treated promptly and appropriately.

What is the Prognosis of Mainland Tiger Snake Bite? (Outcomes/Resolutions)

• The prognosis of Mainland Tiger Snake Bite is dependent on the snake species, site of bite, overall health of the individual, promptness of medical response, and continued observance and treatment of complications following admission of the patient. In many cases, the prognosis is good with immediate treatment and administration of antivenom
• Without treatment or access to proper healthcare, deaths are reported in 40-60% of the cases. Individuals typically die from severe blood and heart-related abnormalities including neurotoxicity and multiple organ failure

Additional and Relevant Useful Information for Mainland Tiger Snake Bite:

• In some cases, the snake bite may be a ‘dry bite’, meaning that even though there is a bite mark, no venom injection occurs. However, even for dry bites, the patient must be placed under observation and monitored closely for a period ranging anywhere from 12-24 hours, prior to discharge
• It has to be noted that snakes of the same species may vary in their physical and biological characteristics, including in their habitat and prey, from one geographical region to another. Due to this, it is always recommended to consult your local (zoological) expert to understand or evaluate the nature of the snake, including whether it is venomous or non-venomous

Depending on the geographical region, either monovalent antivenom or polyvalent antivenom may be administered for systemic envenomation. Monovalent antivenom neutralizes venom of a single snake species only, whereas polyvalent antivenom can neutralize the venom of several snake species.

The snake venom is a highly complex mix of several proteins, enzymes, amino acids, peptide chains, fats, and even certain metals. The bite causing venom injection into the body may be categorized as:

• Intramuscular injection: Long-fanged snakes have a potential for injecting venom directly into the muscles (this is highly infrequent though)
• Intraperitoneal injection: When the snake bite involves the stomach or abdomen region
• Intravenous injection: In very rare cases, the snake fangs may inject venom directly into a blood vessel, releasing venom directly into blood (posing an even greater danger than normal snake bites)
• Subcutaneous injection: A majority of snake bites involve the subcutaneous skin layers (venom is injected just below the skin surface)