INTRODUCTION	Section 2 of 11
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography

Background: Coelenterates are in the phylum of aquatic invertebrates responsible for more envenomations than any other marine phylum. Close to 9000 species of coelenterates are known, of which approximately 100 are toxic to humans. These animals have a gastrovascular cavity with a single opening used in digestion and circulation. Another characteristic feature is the presence of stinging cells (ie, nematocysts). The phylum is divided into 4 major classes: (1) Hydrozoa (Portuguese man-of-war and fire coral), (2) Scyphozoa (true jellyfish), (3) Cubozoa (box jellyfish), and (4) Anthozoa (soft corals and sea anemones).

Pathophysiology: The toxin of coelenterates is located in cnidocytes, which are stinging cells composed of organelles called nematocysts. Nematocysts are present on the outer surfaces of tentacles or near the mouth. Nematocysts are contained within the cnidoblast or the outer capsule. On the external surface of the cnidoblast is the cnidocil (trigger point), which can be triggered by mechanical or chemical stimuli. At the base of the cnidocil is a hollow, coiled, sharp, pointed, threaded tube containing venom.

The majority of toxins contain a complex mixture of polypeptides and proteins including (1) catecholamines, (2) histamine, (3) hyaluronidase, (4) fibrolysins, (5) kinins, (6) phospholipases, and (7) various hemolytic, cardiotoxic, and dermatonecrotic toxins.

Hydrozoa class

The Hydrozoa class contains Physalia species (ie, Portuguese man-of-war) and hydroid corals. Portuguese man-of-war is a free-swimming organism with tentacles hanging from the float (ie, main body). The 2 species are (1) the larger Physalia physalis, which is found in the Atlantic Ocean from Nova Scotia to the Caribbean Sea; and (2) the smaller Physalia utriculus, which is found in the Pacific and Indian Oceans. Tentacles may reach up to 100 feet in length and contain up to a million nematocysts. Detached tentacles on the beach are hazardous as they are capable of releasing venom for several weeks. Two confirmed deaths have been attributed to Physalia physalis.

The fire corals (Millepora) typically are encountered off the Florida coast and in the Caribbean.

Hydroid corals are sessile creatures that can attach to rocks, coral, seaweed, or pilings. A typical reaction is a mild stinging sensation with occasional development of burning pain and lymphadenopathy.

Scyphozoa class

The Scyphozoa class contains true jellyfish. In the United States, true jellyfish are the most common coelenterate species to cause envenomation. Sea nettles Chrysaora species and Cyanea species are located along the Atlantic coast, with a high concentration near the Chesapeake Bay. Envenomations caused by organisms in the class Scyphozoa are less severe than those caused by Portuguese man-of-war.

Cubozoa class

The Cubozoa class contains the most toxic marine organisms, box jellyfish (Chironex fleckeri) and sea wasp (Chiropsalmus quadrigatus). These animals are found in northern Australian waters and have not been reported in North American waters.

Anthozoa class

Anthozoa class contains sea anemones and corals. Most Anthozoa organisms are sessile creatures, and anemones found within the US tidal zones have minimal toxicity.

Corals

Corals are important components of living reefs. Risk of infection from a coral cut is of greater concern than the toxic effects of the coral.

Frequency:

• In the US: Coelenterate envenomations occur in coastal areas of the United States, with highest frequency during summer. Envenomations by jellyfish are most common. Envenomations by Physalia species cause many ED visits in Florida and Hawaii.

• Internationally: An estimated 40,000-50,000 marine envenomations occur annually.

  Approximately 10,000 coelenterate envenomations occur each summer off of the east coast of Australia.

Mortality/Morbidity: Fatal envenomations due to box jellyfish occur in tropical waters of northern Australia. Fatalities have occurred rapidly, within 60 seconds, from this species. At least 63 deaths have been documented.

	CLINICAL	Section 3 of 11
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography

History:

• Envenomations usually result in 3 main types of mechanisms: immediate allergic, immediate toxic, and delayed allergic response.

• Obtain the following information regarding the envenomation:

• Time of envenomation

• Nature of incident - Geographic location, quality of symptoms, progression of symptoms

• Description of animal

• Toxicity depends on the following:

• Age of patient

• Underlying health of patient (especially those with hepatic disease)

• Potency of venom

• Number of nematocysts triggered

• Amount of skin involved

• Look for envenomation lesions in patients with unexplained near drowning or collapse in water.

Physical:

• Most common presentation is a painful papular-urticarial eruption at the site of contact.

• Lesions can last for minutes to hours, and the rash may progress to urticaria. Further progression can lead to vesicular, hemorrhage, or necrotizing lesions. "Sea lice" or sea bather's eruption affects covered areas of the body and is a result of trapped larvae of certain thimble jellyfish. The severely pruritic urticarial lesions can last up to 2 weeks.

• Ocular contact has resulted in conjunctivitis, chemosis, corneal ulcerations, and lid edema.

• Chronic reactions include keloids, granulomas, hyperpigmentations, fatty atrophy, contractions, and vascular spasms.

• Uncommon local reactions include angioedema, recurrent reactions, contact dermatitis, and papular urticaria.

• Ingestion of jellyfish has resulted in abdominal pain, cramping, and generalized urticaria.

• Systemic reactions can develop with local cutaneous findings, including weakness, headache, nausea, vomiting, muscle spasm, fever, pallor, syncope, respiratory distress, and paresthesias.

• Irukandji syndrome can occur, consisting of backache, arthralgias, myalgias, vomiting, sweating, pyrexia, tachycardia, dyspnea, and hypertension after envenomation by the small jellyfish Carukia barnesi. Although the systemic reaction can be significant, the sting frequently is not visible.

• Hypersensitivity reactions may occur but anaphylaxis is rare.

• Venom of the box jellyfish or sea wasp can induce respiratory and myocardial arrest.

• Deaths have been reported within minutes after release of the venom.

• Over 60 deaths have been reported in northern Australia as a result of C fleckeri stings. Deaths also can occur by drowning secondary to incapacitation following painful envenomations.

• Systemic reactions can include headache, malaise, fever, nausea, vomiting, muscle spasm, pallor, respiratory distress, hemolysis, and acute renal failure.