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

• Calloselasma Rhodostoma Snake Bite
• Malayan Ground Pit Viper Snake Bite
• Trigonocephalus Rhodostoma Snake Bite

What is Malayan Pit Viper Snake Bite? (Definition/Background Information)

• The Malayan pit viper (Calloselasma rhodostoma) is a highly venomous and aggressive snake found in many parts of Southeast Asia including peninsular Malaysia, Thailand, Vietnam, Java islands, Cambodia, Indonesia, and Laos
• The snake belongs to the sub-species of pit vipers (family Viperidae) and is found in altitudes ranging from mean sea level to up to 6,500 feet (2,000 m). Pit vipers are termed so, due to the presence of certain heat-sensing organs located in a recess/notch between their eyes and nostrils
• An adult Malayan pit viper female can grow to reach nearly 3 feet or more in length, but adult males are about 6 inches shorter. The average length and coloring pattern of the snake varies from one geographical region to another
• The Malayan pit viper is a land-dwelling reptile that is usually territorial in nature. It can be found near cultivations (farms, orchards, and plantations), rocky slopes, and low density coastal forests. Since, it commonly preys on rats and mice, the snake is often found near large rice paddy fields
• The snake body is flat, but thick, with a short tail. It has a large triangular-shaped head with a subtle, but easily identifiable upwards pointing snout. The color of the Malayan ground pit viper may be red-brown, yellow ochre, or grayish. A series of dark crisscross patterns may be observed from the head to tail
• Most Malayan pit vipers are nocturnal in nature, but some may hunt during the day. The color and body markings make the snake hard to spot; it also remains motionless to ambush prey such as rats, frogs, lizards, and sometimes, even birds
• The Malayan pit viper is highly-irritable and is known to strike at the slightest provocation. Human interactions are frequent, since it is a commonly found reptile in certain highly-populated Asian regions. Malayan Pit Viper Snake Bites can cause systemic envenomation (venom injection) that result in fatalities, without prompt and adequate treatment
• The signs and symptoms of Malayan Pit Viper Bite may include intense pain and swelling at the bite site, which is progressively followed by nausea and vomiting, dizziness, shock, and collapse. The venom can result in clotting defects leading to extensive internal bleeding
• Early administration of suitable antivenom (or antivenin) is the mainstay of treatment. Apart from this, symptomatic treatment is necessary, which may include pain medication, respiratory support, and blood transfusions. The prognosis of Malayan Pit Viper Snake Bite with immediate and effective therapy is usually good

Who gets Malayan Pit Viper Snake Bite? (Age and Sex Distribution)

• Malayan Pit Viper 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
• Malayan pit vipers are distributed across many Southeast Asian nations. These include west and north Malaysia, Thailand, Vietnam, Myanmar, southeast Cambodia, Laos, Indonesia, and Java (island)

What are the Risk Factors for Malayan Pit Viper Snake Bite? (Predisposing Factors)

The risk factors for Malayan Pit Viper Snake Bite include the following factors:

• Living or residing in areas where the Malayan Pit viper is found; especially, in the country side and rural regions of the endemic zones
• People working on agricultural lands and cultivations that include rice fields, rubber and coffee plantations, orchards, and large farmlands
• The snake can be found in coastal forests and near dense bamboo plant growths. Walking barefoot or unprotected through such areas can increase the risk for snake bite
• Venturing outdoors during the night, especially for toilet; the snakes are often seen crossing footpaths and walkways and treading accidents are known to occur
• During nights, the snake may enter easily accessible households in search of prey (such as mice and rats) and inadvertently strike humans
• In snake-infested areas, having thatched or hay mounted roofs (or even cracked mud walls) may offer them space to cool and hide
• Walking or sleeping in farms and fields, particularly at night (usually noticed among migrant workers) and during harvest seasons
• Wildlife enthusiasts and scientific study groups, who explore the region
• Keeping them as pets
• Handling dead or live pit vipers; 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 Malayan Pit Viper Snake Bite? (Etiology)

Malayan Pit Viper Snake Bite takes place when one comes into contact with the venomous and dangerous Malayan pit viper, usually unintentionally or inadvertently.

• The snake can inject a potent hemotoxin that interferes with normal blood coagulation, resulting in severe hemorrhage
• The severity of the signs and symptoms depending on key factors such as the location of the bite, age and health condition of the individual, and one’s body weight
• According to scientific literature, the rates of envenomation of Malayan pit vipers are between 60-80%

Note: According to the World Health Organization (WHO), up to 50% of Malayan Pit Viper Bites are ‘dry bites’ and do not lead to any local or systemic envenomation (i.e., no signs and symptoms may be noted).

What are the Signs and Symptoms of Malayan Pit Viper Snake Bite?

The signs and symptoms of Malayan Pit Viper 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 potency and amount of venom injected.

The common signs and symptoms of Malayan Pit Viper Bite that may develop within a period of a few hours may include:

• Severe pain at the bite site; presence of noticeable fang marks
• In a majority of cases, snake bites occur on the feet and ankles followed by the hands
• Skin discoloration and swelling that slowly involves a wider region
• Blistering of skin (like formation of bubbles)
• Bleeding from the wound
• Swollen lymph nodes
• Breathing difficulties
• Nausea and vomiting
• Vomiting or coughing-up blood
• Blood in urine
• Abdominal pain and diarrhea
• Sweating
• Death of tissue (or necrosis) around the affected region or limb, observed within a few days
• Low blood pressure
• Fainting, dizziness
• Weakness and malaise
• Partial consciousness or unconsciousness

Some of the systemic signs and symptoms may include:

• Decreased blood platelets (thrombocytopenia) resulting in clotting defects
• Internal hemorrhage and gastrointestinal bleeding
• Anemia due to spontaneous bleeding
• In rare cases, acute kidney injury or kidney failure
• Neurological symptoms are not commonly noted

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 Malayan ground pit viper 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 Malayan Pit Viper Snake Bite Diagnosed?

Malayan Pit Viper 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
  • Calcium and phosphorus blood tests
  • 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
• Electrocardiogram (ECG)
• Kidney function test
• Liver function test

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 Malayan Pit Viper Snake Bite?

The complications of Malayan Pit Viper Snake Bite are uncommon, but may include:

• Multiple bites, causing injection of a large quantity of venom
• The snake mouth is known to contain dangerous pathogens that can result in the onset of infection at the time of bite itself
• Impaired blood coagulation resulting in severe internal bleeding
• Disseminated intravascular coagulation (DIC) resulting in blood clot formation in the body
• Severe deep tissue and muscle damage of the affected leg or hand, which can result in superimposed infections and gangrene formation
• Increased pressure causing compartment syndrome, which is an urgent medical condition
• Local envenomation causing debilitating limb injury and irreversible muscle damage
• Loss of limb function necessitating amputation; physical disabilities are not uncommon with Malayan Pit Viper Bites
• 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
• Respiratory distress
• Severe shock and convulsions
• Paralysis
• Seizures and coma
• Kidney failure, in rare cases

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

How is Malayan Pit Viper 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 following measures may be considered in the treatment of Malayan Pit Viper Snake Bite, based on the medical evaluation of a trained healthcare professional:

• Administration of intravenous fluids 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
• Adequate wound care to prevent secondary infections
• 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 (platelet) and plasma transfusions for severe cases
• Medications to increase blood pressure such as vasopressor drugs and plasma expanders
• Peritoneal dialysis for acute kidney failure, if necessary
• Providing life support, such as ventilation assistance and treatment for shock, for those with severe symptoms leading to potential organ failure
• Pressure management (using appropriate pressure devices) of affected limb for compartment syndrome; in rare cases, it may merit a fasciotomy
• Removal or necrotic tissue through surgical debridement
• Rehabilitation of the affected limb through physical therapy

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 Malayan Pit Viper Snake Bite be Prevented?

Malayan Pit Viper Snake Bite may be avoided by:

• Learning to recognize Malayan pit vipers using the following tips:
  • The flat and thick body with a large triangular head; the head of the snake is noticeably inclined upwards from the ground
  • It has a dark-colored body that is red, brown, or dark yellow and with black geometric patterns
  • The snake stays perfectly still and tries to blend into the surrounding, unless disturbed. It is a very aggressive reptile
  • It is generally spotted near rice fields and coffee and rubber plantations
• If you spot a Malayan pit viper, step back slowly and keep a safe distance of at least 8-10 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
• Be on the lookout for snakes and other animals while trekking or hiking; also, if you are with a pet, do not allow the pet to wander away
• Always allow snakes crossing your path the right of way
• Always stay on established paths and clearings, while walking in the forests or through thick undergrowths
• 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 monkeys 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
• Do not reach out to move or hold bushes or tree branches without properly examining them for any camouflaged creatures such as snakes
• 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:

• Be particularly vigilant during agricultural activities, harvest times, and rainy periods
• Use heavy boots and thick pants while clearing or working on large unattended farmlands
• Avoid picking up firewood sticks, stones, or rocks without checking the area for any concealed creatures
• 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
• Educate local communities on how to identify such venomous snakes, their activities, habitats, whether they are ‘day-snakes’ or ‘night-snakes’, their weather preferences, recognize bite symptoms, and how to avoid encounter with snakes
• Teach and educate children about the dangers and importance of 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 Malayan Pit Viper Snake Bite? (Outcomes/Resolutions)

• The prognosis of Malayan Pit Viper Snake Bite is dependent on the size of the snake, site of bite (bites on face or body are more severe), age and 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 from severe complications, such as internal bleeding, organ failure, and shock, have been reported. The death rate without treatment from severe envenomation is about 2-10%

Additional and Relevant Useful Information for Malayan Pit Viper Snake Bite:

• The Malayan pit viper is one among the 3 snakes causing the maximum number of deaths in Thailand. The other two being the cobra and the Malayan krait
• 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)