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

• Collared Brown Snake Bite
• Gwardar Snake Bite
• Strap-Snouted Brown Snake Bite

What is Western Brown Snake Bite? (Definition/Background Information)

• The western brown snake is a common and highly venomous snake that is found extensively across the length and breadth of Australia. The snake belongs to the Elapidae family, which generally includes slender and swift moving snakes
• It is important to note that western brown snakes are a group of three snakes belonging to Pseudonaja species. They vary among each other based on their physical appearance and predominant geographic region they are reported from. The following are the three western brown snakes:
  • Pseudonaja aspidorhyncha, or the strap-snouted brown snake, with a set of broad and narrow dark bands that arise from mid-body to the tail of the snake
  • Pseudonaja mengdeni, or the Mengden's brown snake, with an orange body and black head (and black mouth); some snakes present banding
  • Pseudonaja nuchalis, or the northern brown snake, with brown body and dark brown/black head and neck region; in some, faint bands are noted
• Despite the above, there is still some debate among the experts on their classification. Nevertheless, this is more a matter of taxonomy (nomenclature) and does not in any way change their description, behavior, or venomous nature of the western brown snakes
• This slender and robust snake can grow to sizes ranging from 4 to 6.5 feet in length. The head and neck of the snake are uniform and continuous. The snake is also quite homogeneous in coloration - from dark, shiny, or pale brown/orange on the dorsal surface (top side) and lighter undersides (cream or yellow, or light brown)
• The snake inhabits a vast tropical and temperate territory that ranges from deserts, grasslands, shrublands, forests, coastal areas, to vast croplands. The western brown snake is mostly active during the day, but may prefer to be nocturnal during the hot summer months
• It mostly hunts small lizards, frogs, other snakes, and even small birds. However, since the most abundant prey are mice and rats, the snake tends to frequent farmlands and residential areas, bringing it close to urban and semi-urban areas
• Typically, the snake is an aggressive reptile, though it mostly attempts to escape in the face of danger or disturbance. But, if cornered or provoked, the snake may take an S-shaped raised hood, flat-necked, hissing posture, showing a readiness to strike. Any further provocation at this stage will result in a bite
• The fangs of the snake are comparatively small and no local pain or swelling may be observed initially following a bite. The bite marks also remain very inconspicuous resulting in ignorance of the bite incident in some cases
• Due to its wide distribution across Australia, human interactions are not uncommon. Western Brown Snake Bite can result in fatalities due to systemic envenomation (venom injection through a bite), if the condition is left untreated, due to the presence of highly potent hemotoxins and neurotoxins in the venom
• The signs and symptoms of Western Brown Snake Bite may be non-specific and include headaches, sweating, weakness, nausea and vomiting, abdominal pain, and dizziness. Severe widespread symptoms and complications may involve the cardiovascular, hematological (blood-related), and kidney and urinary 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 Western Brown Snake Bite with prompt and effective therapy is usually good

Who gets Western Brown Snake Bite? (Age and Sex Distribution)

• Western Brown Snake Bite may occur to any individual exposed to the snake, particularly in its natural habitat
• Individuals of any age and gender are prone to snake bites
• Western brown snakes are distributed across the entire Australian continent, which includes the following states:
  • Western Australia, except for the southern regions of the state
  • Northern Territory
  • Queensland, but for the eastern regions
  • New South Wales
  • South Australia, but for the southeastern corner
  • Victoria, in a few pockets in the northwest corner

What are the Risk Factors for Western Brown Snake Bite? (Predisposing Factors)

The risk factors for Western Brown Snake Bite include the following factors:

• Living or residing in areas where the western brown snake is found; there is a higher risk for people in the country side and rural regions of the endemic zones
• Occupational hazard: The snake may pose a threat to those working in farmlands, plantations, and herding cattle
• Walking barefoot or unprotected through open grasslands, savannahs, and open woodlands
• Venturing outdoors during the night
• The snake is also known to take shelter in ground cracks and near stone or rubbish piles close to residential areas
• Walking or sleeping in farms and fields, particularly at night and during harvest seasons
• The snakes are known to climb low-lying bushes or small trees, thus putting individuals at risk near bushy thickets
• Professional snake catchers
• Wildlife enthusiasts and scientific study groups, who explore the region
• Keeping them as pets
• Handling dead or live western brown 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 Western Brown Snake Bite? (Etiology)

Western Brown Snake Bite takes place when one comes into contact with the venomous western brown snake, usually unintentionally or inadvertently.

• Individuals, who disregard the warning signs of puffing and raised (zigzag) posture of the snake, have a greater risk of being bitten by the western brown snake. The snake has a nervous disposition and is known to inject a large quantity of venom with a single bite
• Western Brown Snake Bites can cause the injection of a hemotoxic-neurotoxic venom into the body. The venom can affect the blood, cardiovascular, and neurological system resulting in low blood pressure, bleeding disorders, and occasionally, associated neurological symptoms

According to scientific literature, the rate of envenomation of the western brown snake is between 20-40%.

What are the Signs and Symptoms of Western Brown Snake Bite?

The signs and symptoms of Western Brown 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 snake species, potency, and amount of venom injected.

The common signs and symptoms of Western Brown Snake Bite that may develop over a few hours may include:

• Local effects at the bite site:
  • Pain at the bite site is minimal to absent
  • Fang marks may not be noticeable (the fangs are only about 2-3 mm in length)
  • Swelling (or other local reaction) is not known to occur
• In a majority of cases, the bites occur on the limbs
• Headaches
• Sweating
• Nausea and vomiting
• Abdominal pain and diarrhea
• Fainting, dizziness
• Weakness and malaise

Some of the systemic signs and symptoms that may develop in the affected individuals 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
  • Mucosal bleeding (seen a few hours after the bite) from the gums, eye, gastrointestinal tract, etc.
  • Anemia due to spontaneous bleeding
• Acute kidney injury or kidney failure, in some
• Neurological symptoms are uncommon; paralysis is rare

Note: 

• In a majority of 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 western brown 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 Western Brown Snake Bite Diagnosed?

Western Brown 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 Western Brown Snake Bite?

The complications of Western Brown Snake Bite may include:

• Multiple bites, causing injection of a large quantity of venom
• Blood clotting defects resulting in severe internal bleeding
• Hemolytic anemia
• 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
• Cardiac arrest

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 Western Brown 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 generally 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 Western Brown 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; the type administered is brown snake antivenom (BSAV)
• 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 Western Brown Snake Bite be Prevented?

Western Brown Snake Bite may be avoided by:

• Learning to recognize western brown snakes using the following tips:
  • Length of the snake is 4-5 feet or more; uniform body in size and coloration (brown to orange) with some amount of banding towards the rear of the snake
  • The snake is quick-moving and is mostly active during the day
  • When approached, the snake may provide warning signs of loud hissing and appear to flatten its neck
  • Raised head, neck, and upper body of the snake is presented in a curved “S” shaped posture, indicating a willingness to face the threat and strike if necessary
• If you spot a western brown 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 large 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
• In regions where snakes are regular home visitors, always switch on the lights before entering one’s shed or garages (and try to stand clear of exits that may serve as possible escape routes for the snakes)
• 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 have the potential for severe envenomation; hence, all snake bites should be treated promptly and appropriately.

What is the Prognosis of Western Brown Snake Bite? (Outcomes/Resolutions)

• The prognosis of Western Brown Snake Bite is dependent on the 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 10-20% of the cases. Individuals typically die from severe blood and heart-related abnormalities including cardiac arrest

Additional and Relevant Useful Information for Western Brown Snake Bite:

• Western brown snakes kill their prey through venom injection. However, following the bite, the snake also latches on to the prey and coils around it constricting its movement, before it is swallowed whole
• 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

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)