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Box jellyfish

Phylum coelenterata, Class Scyphozoa (true jellyfish, sea wasp) and
Class Hydrozoa (hydroids, Man-of -War).

These possess nematocysts, a stinging apparatus formed within the cnidoblast and discharged on contact. Floating tentacles retain active nematocysts, which remain active even after drying. There is a wide range of toxicity, from mild to severe (Portugese Man-o-War, Physalia utriculus), and sea wasp, genera Chironex.

<>The venom is complex, and includes proteins, enzymes, polypeptides and tetramine. Pain and local histamine release attributed to 5-hydroxytryptamine; the nerve conduction effects are due to tetramine (similar to curare).

Symptoms: Rapid onset of pain, varying from mild to severe. A rash that is red, hot and swollen, usually linear. There is frequent pustule and vesicle formation. Anaphylaxis (circulatory collapse) is possible in sensitized individuals. Severe stings may cause muscle cramps, abdominal pain, fever, chills, nausea, vomiting, respiratory distress, and cardiovascular collapse. Fatalities are increased if there is pre-existing cardiac and respiratory disease. Chironex may cause death in healthy individuals in less than 15 minutes.

Treatment: Use topical vinegar to neutralize undischarged nematocysts and removal of remaining tentacles. Flush with sea water rather than fresh  water.  Topical analgesics and steroids or IV analgesics and hydrocortisone 100 mg IV every two hours are given. (Chironex).
Cardiovascular monitoring and/or support are provided. Sea wasp antivenin is available (Australia Commonwealth Serum Lab.)

Australian researchers have found that vinegar will cause firing of about 30% of nematocysts of the Physalia species. Others have found that  alcohol  will also cause nematocysts to fire.  The latest recommendations  for emergency care can be found in this article from eMedicine, updated  June 3, 2005, iwhich acetic acid and 70% alcohol is recommended to denature the nematocysts.  Also, one authority states that flushing with sea water exposes the injury to the risk of infection with marine organisms.  So, there is a debate as to the appropriate fluid that best deactivates the nematocysts. Burnett advisesrinsing with one part baking soda and one part water—or sea water.

               Treatment of Severe Allergic Reaction to Jellyfish

               Remove any remnant of allergen (i.e., jellyfish tentacles, foreign
                    Epinephrine injection, if available
                    Decadron injection or tablets
                    Antihistamine, if available
                    Wash out wounds or injury with vinegar or sea water
                    Call for help and immediate transport
                    Treat for shock
                    CPR if no pulse or respirations
                    Keep warm
                    Pain relief, if available

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