Sea Snake Envenomation

Author: Dimitrios Papanagnou, MD, MPH; Chief Editor: Rick Kulkarni, MD more...

Updated: Feb 8, 2011

What would you like to print?

Background
Pathophysiology
Epidemiology
Show All

Background

Sea snakes, venomous elapid snakes that inhabit marine environments, are the most abundant and widely dispersed group of poisonous reptiles in the world. They comprise approximately 70 species, 50 of which are members of the family Hydrophiidae. Sea snakes are characterized by laterally compressed bodies and vertically flattened tails and nostrils with valve-like flaps, giving them an eel-like appearance. Their most characteristic feature is a paddle-like tail, which increases their swimming ability.^[1]Unlike eels, however, sea snakes have scales but lack gills or fins. Although they spend much of their time underwater, they must surface regularly to breathe. They are typically about 1 m in length, but some species may grow to 3 m. See the image below.

Yellow-belly pelagic sea snake.

Sea snakes are found in warm coastal waters, predominantly in tropical and subtropical waters in the western Pacific and Indian Oceans. They are usually found in protected coastal waters and near river mouths. However, they are able to thrive in a variety of habitats, ranging from muddy or turbid water, to clear waters and coral reefs. Most species prefer shallow waters not far from land, around islands. The pelagic sea snake, Pelamis platurus, has a remarkably wide geographic range, reaching the western coasts of North America and South America from the Baja peninsula to Ecuador, along with the waters around Hawaii. Sea snakes are not found in the Atlantic Ocean, the Caribbean, or along the North American coast north of Baja.

Generally, sea snakes are not aggressive with gentle dispositions. They are not thought to bite humans unless provoked, and they typically do not actively pursue swimming prey. Sea snakes have been noted to become quite aggressive, when they are taken out of water, exhibiting erratic movements and striking anything near them that moves.^[2]

Pathophysiology

Among this group are species with some of the most potent venoms of all snakes. The venom apparatus of sea snakes is fairly rudimentary, consisting of 2-4 short hollow maxillary fangs associated with a pair of venom-producing glands. The venom ducts open near the tips of the fangs. The fangs are dislodged easily from their sockets and may remain embedded in the skin of victims.

Nearly 80% of sea snake bites fail to produce significant envenomation, and bites may be inconspicuous, painless, and free of edema. Usually, little or no swelling is involved, and it is rare for any nearby lymph nodes to be affected. However, sea snake venom is extremely potent, and a complete envenomation by an adult sea snake may contain enough venom to kill 3 adult people.

The clinically relevant toxins in sea snake venom are neurotoxins and myotoxins. The primary neurotoxin causes peripheral paralysis by competitively binding to postsynaptic nicotinic acetylcholine receptors at the neuromuscular junction. Potent myotoxins account for the significant muscle necrosis, with consequent myoglobinemia and hyperkalemia that may occur following envenomation. Sea snake venom does not affect blood coagulation to a significant degree.

Sea snakes are closely related to Australian elapids; therefore, some paraspecificity exists between sea snake antivenom and Australian elapid antivenom.

Frequency

United States

Hawaii is the only US state where sea snakes are found.

International

Sea snake envenomations occur throughout the serpents' geographic ranges, but accurate data about the incidence of envenomation are not available. Victims most commonly are fishermen bitten while handling nets or after stepping on a snake.

Mortality/Morbidity

Before the development of sea snake antivenom, the mortality rate associated with sea snake bites was approximately 10%. With timely administration of antivenom and aggressive supportive care, the mortality rate currently is much lower, although accurate numbers are not available.

Race

No inherent racial predilection exists for sea snake bites; however, the best-represented races in areas with endemic sea snake populations are the most commonly bitten.

Sex

Males are bitten much more commonly than females, with a male-to-female ratio of approximately 4:1, because of the increased occupational exposure to sea snakes by male fishermen.

Age

Age is a factor in determining sea snake bites only insofar as it occurs with potential recreational or occupational exposure to the serpents.

Proceed to Clinical Presentation

Contributor Information and Disclosures

Author

Dimitrios Papanagnou, MD, MPH Staff Physician, Department of Emergency Medicine, Bellevue Hospital Center

Dimitrios Papanagnou, MD, MPH is a member of the following medical societies: American College of Emergency Physicians, American College of Physicians-American Society of Internal Medicine, American Medical Student Association/Foundation, and Emergency Medicine Residents Association

Disclosure: Nothing to disclose.

Coauthor(s)

Susi U Vassallo, MD, FACEP, FACMT Assistant Professor of Emergency Medicine, New York University School of Medicine/Bellevue Hospital Center

Susi U Vassallo, MD, FACEP, FACMT is a member of the following medical societies: American Academy of Clinical Toxicology, American College of Emergency Physicians, American College of Medical Toxicology, New York Academy of Medicine, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Robert L Norris, MD Professor, Department of Surgery, Chief, Division of Emergency Medicine, Stanford University Medical Center

Robert L Norris, MD is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, California Medical Association, International Society of Toxinology, Society for Academic Emergency Medicine, and Wilderness Medical Society

Disclosure: Nothing to disclose.

John T VanDeVoort, PharmD Regional Director of Pharmacy, Sacred Heart and St Joseph's Hospitals

John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists

Disclosure: Nothing to disclose.

James Steven Walker, DO, MS Clinical Professor of Surgery, Department of Surgery, University of Oklahoma College of Medicine

James Steven Walker, DO, MS is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Osteopathic Emergency Physicians, and American Osteopathic Association

Disclosure: Nothing to disclose.

John D Halamka, MD, MS Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center

John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Chief Editor

Rick Kulkarni, MD Attending Physician, Department of Emergency Medicine, Cambridge Health Alliance, Division of Emergency Medicine, Harvard Medical School

Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: WebMD Salary Employment

Additional Contributors

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, James Foster, MD, to the development and writing of this article.

References

Food and Agriculture Organization. Sea Snakes. United Nations; August 2007. [Full Text].
Ditmars RL. The MacMillan Company. Reptiles of the World, Revised Edition. 1933:329, pp 89.
Auerbach PS. Marine envenomations. N Engl J Med. Aug 15 1991;325(7):486-93. [Medline].
Auerbach PS. Marine envenomations. In: Auerbach PS, ed. Wilderness Medicine: Management of Wilderness and Environmental Emergencies. 3^rd ed. Mosby-Year Book; 1995:1327-74.
Baxter EH, Gallichio HA. Cross-neutralization by tiger snake (Notechis scutatus) antivenene and sea snake (Enhydrina schistosa) antivenene against several sea snake venoms. Toxicon. May 1974;12(3):273-8. [Medline].
Chetty N, Du A, Hodgson WC, et al. The in vitro neuromuscular activity of Indo-Pacific sea-snake venoms: efficacy of two commercially available antivenoms. Toxicon. Aug 2004;44(2):193-200. [Medline].
Dunson WA. The Biology of Sea Snakes. Baltimore, Md: University Park Press; 1975.
Guenin DG, Auerbach PS. Trauma and envenomations from marine fauna. In: Tintinalli, et al, eds. Emergency Medicine: A Comprehensive Study Guide. 4^th ed. McGraw-Hill; 1996:868-73.
Heatwole H. Sea Snakes. Krieger Publishing Company; 1999.
Minton SA Jr. Paraspecific protection by elapid and sea snake antivenins. Toxicon. Jul 1967;5(1):47-55. [Medline].
Pinney R. Sea snakes. Reptile & Amphibian. 1994;26:22-34.
Reid HA. Antivenom in sea-snake bit poisoning. Lancet. Mar 15 1975;1(7907):622-3. [Medline].
Reid HA. Epidemiology of sea-snake bites. J Trop Med Hyg. May 1975;78(5):106-13. [Medline].
Reid HA, Chan KE. The paradox in therapeutic defibrination. Lancet. Mar 9 1968;1(7541):485-6. [Medline].
Senanayake MP, Ariaratnam CA, Abeywickrema S. Two Sri Lankan cases of identified sea snake bites, without envenoming. Toxicon. Jun 1 2005;45(7):861-3. [Medline].
Tu AT. Biotoxicology of sea snake venoms. Ann Emerg Med. Sep 1987;16(9):1023-8. [Medline].
Tu AT, Fulde G. Sea snake bites. Clin Dermatol. Jul-Sep 1987;5(3):118-26. [Medline].
Vick JA. Medical studies of poisonous land and sea snakes. J Clin Pharmacol. Jun 1994;34(6):709-12. [Medline].

Technique for application of pressure immobilization in field management of sea snake bites. Figure 1, Apply a broad-pressure bandage over the bite site as soon as possible. Do not take off jeans because the movement of doing so assists venom to enter the bloodstream. Keep the bitten leg still. Figure 2, The bandage should be as tight as would be applied to a sprained ankle. Figure 3, Extend the bandage as high as possible.

Technique for application of pressure immobilization in field management of sea snake bites. Figure 4, Apply a splint to the leg. Figure 5, Bind the splint firmly to as much of the leg as possible. If the bandages and splint are applied correctly, they will be comfortable and may be left on for several hours. They should not be taken off until the patient has reached medical care. The doctor will decide when to remove the bandages. If venom has been injected, it will move into the bloodstream quickly once the bandages are removed. The doctor should leave the bandages and splint in position until he or she has assembled appropriate antivenom and drugs that may need to be used when the dressings and splint are removed. Figure 6, For bites on a hand or forearm, bind to the elbow with bandages, use a splint to the elbow, and use a sling.