Nematocysts: Difference between revisions
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===Mechanism=== | ===Mechanism=== | ||
[[File:Nematocyst discharge.png|thumb|Nematocyst stages of discharge]] | [[File:Nematocyst discharge.png|thumb|Nematocyst stages of discharge]] | ||
*Physical contact or osmotic gradient causes discharge of | *Physical contact or osmotic gradient causes discharge of nematocysts | ||
*A spring loaded venom delivery system | *A spring loaded venom delivery system | ||
*Once opened, a nematocyst releases all of its contained venom | |||
==Clinical Features== | ==Clinical Features== | ||
Revision as of 23:17, 1 May 2017
Background
- Jellyfish; box jellyfish is most deadly
- Most toxic: Australia and other Indo-Pacific waters
Mechanism
- Physical contact or osmotic gradient causes discharge of nematocysts
- A spring loaded venom delivery system
- Once opened, a nematocyst releases all of its contained venom
Clinical Features
- Isolated stinging
- Severe
- Respiratory paralysis
- Cardiovascular collapse
- Limb paralysis
- Death
Irukandji syndrome
- Myalgias, back, chest,
- Abdominal pain
- Nausea and vomiting
- Diaphoresis
- Hypertension
- Tachycardia
- Myocardial injury
- Pulmonary edema
Differential Diagnosis
Marine toxins, envenomations, and bites
- Toxins
- Ciguatera
- Scombroid
- Tetrodotoxin (e.g. pufferfish)
- Shellfish poisoning
- Amnesic shellfish poisoning
- Diarrheal shellfish poisoning
- Neurotoxic shellfish poisoning
- Paralytic shellfish poisoning
- Stingers
- Venomous fish
- Cone shell
- Lionfish
- Sea urchins
- Crown-of-Thorns Starfish
- Stonefish
- Other: Catfish, zebrafish, scorpion fish
- Nematocysts
- Coral reef
- Fire coral
- Jellyfish (Cnidaria)
- Portuguese man-of-war
- Sea anemones
- Seabather's eruption
- Phylum porifera (sponges)
- Bites
- Infections
Evaluation
- Generally a clinical diagnosis
Management
- Remove tentacles and nematocysts
- Hot water immersion (inactivates heat labile toxins)
- Consider topical lidocaine
- Consider oral or parenteral analgesia for severe pain
- Acetic Acid may inhibit or trigger nematocyst discharge and thereby increase or decrease pain depending on species
- Symptomatic treatment for Irukandji syndrome
- Antivenom is available for severe box-jellyfish sting
Avoid
- Urine, ethanol, ammonia
- Fresh or tap water (causes nematocyst discharge via the osmotic gradient)
Disposition
See Also
References
- Ward NT, Darracq MA, Tomaszewski C, et al. Evidence based treatment of jellyfish stings in North America and Hawaii. Ann Emerg Med. 2012;60(4):339-414.
- Cegolon L, Heymann WC, Lange JH, et al. Jellyfish stings and their management: a review. Mar Drugs. 2013;11(2): 523-50