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Annulated Sea Snake Bite

Last updated April 11, 2019

Approved by: Maulik P. Purohit MD MPH

The annulated sea snake (Hydrophis cyanocinctus) is a highly venomous snake belonging to the family Elapidae, which generally includes slender and swift moving snakes.


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

  • Blue-Banded Sea Snake Bite
  • Dusky-Chinned Giant Sea Snake Bite
  • Hydrophis Cyanocinctus Snake Bite

What is Annulated Sea Snake Bite? (Definition/Background Information)

  • The annulated sea snake (Hydrophis cyanocinctus) is a highly venomous snake belonging to the family Elapidae, which generally includes slender and swift moving snakes. The snake has a wide geographical distribution and is known by several names including dusky-chinned giant sea snake and blue-banded sea snake
  • Hydrophis cyanocinctus belongs to snakes of subfamily Hydrophiinae that comprise over 50 species of “truly aquatic” sea snakes. The Hydrophiinae are completely adapted to marine life and habitat having minimal terrestrial association and limited land movement
  • Annulated sea snakes are found predominantly along lagoons, mangrove swamps, and river mouths - from Persian Gulf, across Indian Ocean, to East and South China Sea up to the western Pacific Ocean. The coastal shallow waters, mangroves, and wetlands are its primary habitats, where it feeds on fish (including eel and goby)
  • Since, these sea snakes are found across a wide geographical region, their physical attributes, such as size and coloring pattern, including prey, varies from one region to another. Annulated sea snakes are amongst the largest of the sea snakes in the world
  • An adult snake may reach about 4-5 feet in length; although, snakes nearly 6.5 feet in length have been recorded. Females are generally bigger and longer than males. The snake has a medium-sized body, a short head with a horseshoe marking, and a flattened paddle-like tail, to help it swim
  • The annulated sea snake has a light yellow to olive green body (sometimes light gray body) with thick dark bands, which are thinner towards the head and neck and tail regions. The bands may be partial and tapering towards the sides and underbelly of the snake
  • Mostly, it is the fishing and coastal-dwelling communities in the endemic regions, which come into accidental contact with this sea creature. Unlike many sea snakes, the annulated sea snake is not a gentle and non-aggressive snake, even though it avoids humans. It is known to bite readily, even under the slightest of provocation
  • This bite of sea snakes may go unnoticed; the bites are also quite painless or produce minimal pain. Nonetheless, the Annulated Sea Snake Bite can cause life-threatening to fatal envenomation (venom injection), without prompt and adequate treatment
  • The signs and symptoms of Annulated Sea Snake Bite may be apparent within a few hours following a bite. The snake venom is highly potent and neurotoxic, which can cause systemic symptoms such as severe fatigue, muscle weakness, respiratory failure, and total paralysis
  • Early administration of suitable antivenom (or antivenin) is the mainstay of treatment. Apart from this, symptomatic treatment is necessary, which may include pain medication, hydration, and respiratory support. The prognosis of Annulated Sea Snake Bite with immediate and effective therapy is usually good

Who gets Annulated Sea Snake Bite? (Age and Sex Distribution)

  • Annulated Sea Snake Bite may occur to any individual exposed to the snake, usually in the coastal/mangrove areas or while at sea (when fishing or diving)
  • Individuals of any age and gender are prone to sea snake bites in the endemic zones
  • The geographical distribution of annulated sea snake is noted along coastlines from the Arabian Gulf, along Indian Ocean and South China Sea, to the islands in western Pacific Ocean:
    • United Arab Emirates, Iran, Oman, Qatar, Kuwait, Bahrain, and Saudi Arabia
    • Indian subcontinent region including Pakistan, India (most coastal states, especially Kerala and Andaman and Nicobar Islands), Bangladesh, and Sri Lanka
    • Southeast Asian nations of Thailand, Philippines, Singapore, Brunei, Indonesia, Malaysia, Cambodia, Vietnam, and Burma
    • East Asian nations including parts of China, Hong Kong, and Taiwan
    • Northern parts of Australia bordering the states of Western Australia, Northern Territory, and Queensland
    • New Guinea and Papua New Guinea, islands in western Pacific Ocean

What are the Risk Factors for Annulated Sea Snake Bite? (Predisposing Factors)

The risks for Annulated Sea Snake Bite include the following factors:

  • Living or residing in the coastal regions endemic to the snake; most bites take place on land, due to their awkward movement on land, when they are generally more aggressive and easily agitated
  • Occupational hazard: Fishermen and fisherwomen, while sorting fish, setting out fishing nets, pulling in the ‘catch’
  • Swimmers, surfers, coral reef divers, and beachgoers; the snake may be found in groups near rocky shores, small islands/islets, lagoons, and coral reef or sandy beaches
  • Among the coastal community residing by the seaside - venturing outdoors during the night such as for toilet
  • Marine life enthusiasts and scientific study groups, who explore the region
  • Wading in ocean waters without suitable protective clothing
  • Walking barefoot on the beach or in shallow sea waters
  • Keeping them as pets in aquariums (exotic collection)
  • Handling dead or live 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 Annulated Sea Snake Bite? (Etiology)

Annulated Sea Snake Bite can take place when one comes into contact with the venomous sea snake, usually unintentionally or inadvertently.

  • The sea snake is aggressive and is known to bite readily when threatened. Individuals, who come into contact with the snake, may be bitten under self defense when the snake is provoked
  • The annulated sea snake venom contains strong neurotoxins that can cause paralysis and death; the venom is known to impair neuromuscular transmission. Even though envenomation is rare, the fast-acting venom can cause rapid muscle breakdown and neurological symptoms within a few hours

According to scientific literature, sea snake venom is often many times more potent than land snake venom.

What are the Signs and Symptoms of Annulated Sea Snake Bite?

The signs and symptoms of snake bites depend on the age (whether child or adult), body 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 signs and symptoms of Annulated Sea Snake Bite can vary from one individual to another. It may develop in less than an hour. In general, the signs and symptoms of sea snake bites that are noted with snakes belonging to the subfamily Hydrophiinae include the following:

Initial symptoms observed within 5 minutes to 2 hours may include:

  • Bite or fang marks on arm or leg; in some cases, the teeth may break-off and remain in the wound
  • There may be no pain to negligible pain and swelling at the bite site
  • Nausea, vomiting, and diarrhea
  • Sensation of thick tongue
  • Dryness of throat
  • Headaches
  • Feeling sweaty and/or thirsty
  • Anxiety, drowsiness, and confusion
  • Pain, fatigue, and weak muscles
  • Body aches and muscle aches; stiffness of the body and neck

Symptoms observed after several hours (4-8 hours or more) may include:

  • Abdominal pain
  • Poor reflexes
  • Locally enlarged lymph nodes
  • Drooling from the mouth; uncontrollable saliva flow from the mouth
  • Trismus or difficulty opening mouth (same as lockjaw)
  • Droopy eyelids and blurred vision
  • Breathing difficulties; labored breathing
  • Blabbering, speaking difficulties
  • Feeling faint or dizzy
  • Dark-colored urine
  • Blue-colored skin due to poisoning
  • Weakness and malaise
  • Unconsciousness

It has to be noted that in severe bites, the onset and development of symptoms may be rapid, within 1-2 hours. In such cases, the progress from early symptoms to paralysis, respiratory failure, and/or cardiac arrest may take place suddenly.

Systemic signs and symptoms may include:

  • Generalized muscle damage; progressive muscle weakness
  • Rhabdomyolysis: The skeletal muscle tissue may breakdown quickly
  • Paralysis of voluntary muscles; the affected individuals may be unable to stand, sit, or even raise their arms/legs or neck
  • Difficulty speaking and swallowing
  • Neurological symptoms including moderate to severe paralysis
  • Kidney injury causing acute kidney failure is reported
  • Multiple organs may be involved/affected

Note:

  • In some cases, the fang marks may not be pronounced or even visible. Sometimes, only small scratch marks or lacerations may be observed. Thus, any contact with a sea 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 Annulated Sea Snake Bite Diagnosed?

Annulated Sea 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:
    • Complete blood count (CBC) with differential and platelet count
    • White blood cell count
    • Creatine kinase blood test
    • Lactate dehydrogenase (LDH) test
    • Serum electrolytes including blood urea nitrogen (BUN) and creatinine levels
    • Aspartate transaminase blood test
  • Urine test or urinalysis to test for free protein, myoglobin, and hemoglobin levels
  • Electrocardiogram or ECG, to check for arrhythmias (or irregular heartbeat) and hyperkalemia (increased blood potassium)
  • Kidney function test and liver function test, if necessary
  • 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 Annulated Sea Snake Bite?

The complications of Annulated Sea Snake Bite may include:

  • Breakdown of  muscle tissue in the body or systemic myolysis
  • Tissue and muscle damage, which can result in superimposed infections
  • Hyperkalemic cardiotoxicity due to muscle breakdown
  • Flaccid paralysis that is severe; the onset of paralysis may occur within a few hours following the sea snake bite
  • Loss of respiratory function due to neurological symptoms, which can be fatal
  • Acute kidney failure
  • Cardiac failure
  • 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

How is Annulated Sea Snake Bite Treated?

All sea 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 Annulated Sea Snake Bite, based on the medical evaluation of a trained healthcare professional. 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.

  • Administration of sea snake antivenom, 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
  • Administration of intravenous fluids to keep the patient well-hydrated:
    • Good hydration is important, since potential myolysis (muscle breakdown) can cause severe failure of kidney function
    • Adequate hydration helps in decreasing the risk for kidney damage due to myolysis; hence, continuous measurement of urine output (day and night) is important
  • Periodic blood and urine tests are undertaken for 12-24 hours or more
  • Intubation and respiratory support is usually necessary
  • Tetanus vaccination is usually required, if it is not up to date
  • The patient is 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
  • Administration of pain medication, if needed
  • If necessary, blood and plasma transfusions for severe cases
  • Medications to control blood pressure
  • Peritoneal dialysis for acute kidney failure, if required
  • Providing life support, such as ventilation assistance and treatment for shock, for those with severe symptoms leading to potential organ failure
  • Rehabilitation of the affected limb through physical therapy, if required
  • 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 sea 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 Annulated Sea Snake Bite be Prevented?

Annulated Sea Snake Bite may be avoided by:

  • Completely avoid any sort of water or sea snake, especially in the endemic zones
  • Educating fishing and trawling community about sea snakes and the techniques for handling them, untangling them from fishing nets, etc.
  • Do not ignore warnings of lifeguards or health officials at the beach
  • Wear protective clothing if you plan to swim or dive in infested areas (suitable wet skin or diver’s suit)
  • Generally be aware or watchful of the waters you are in (to the extent possible)
  • Wear protective footwear while walking on beach sand
  • Ensure safety precautions while cleaning marine animal aquariums; wear gloves
  • Marine life explorers and sea adventurers are required to carry marine first aid kit
  • If you spot a sea snake (on land or in shallow waters), step back slowly and keep a safe distance between yourself and the snake
  • Be on the lookout for snakes and other animals while outdoors (especially while exploring small islands and rocky beaches); also, if you are with a pet, do not allow the pet to wander away
  • Be alert, if you are in snake-infested regions, particularly containing dangerous species of snakes
  • Avoid picking up 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
  • Near coastal areas, always check before sitting on dead tree logs, stumps, or a pile of rocks; use a stick to stir or probe around the area
  • Avoiding being on beaches at night; be careful while camping outdoors by seaside
  • 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. Also, some snakes pretend to be motionless or may ‘act dead’ when under threat
  • 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

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

Also, in case of a snake bite, do visit a registered medical practitioner immediately (and not any native or traditional medicine experts).

What is the Prognosis of Annulated Sea Snake Bite? (Outcomes/Resolutions)

  • The prognosis of Annulated Sea Snake Bite is dependent on the site of bite, age and overall health of the individual, promptness of medical response, and continued observance and treatment of complications following admission of the patient. However, the overall prognosis is primarily based on the quickness with which suitable antivenom is administered
  • Without treatment or access to proper healthcare, deaths from severe complications, such as respiratory distress, severe paralysis, and organ failure are reported

Additional and Relevant Useful Information for Annulated Sea 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
  • 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)

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: April 11, 2019
Last updated: April 11, 2019