Inadvertent contact with this aquatic species causes excruciating pain and an overwhelming sense of impending doom. What is this?
- Box Jellyfish (Chironex fleckeri)
- Irukandji Jellyfish (Carukia barnesi)
- Lion’s Mane Jellyfish (Cyanea capillata)
- Portuguese Man o’ War (Physalia physalis)
Answer: 2 – Irukandji Jellyfish (Carukia barnesi)
What is Irukandji Syndrome [1-4]?
- Irukandji Syndrome is a sensation of extreme pain and agitation and a feeling of impending doom following envenomation by the Irukandji jellyfish and associated species.
- This jellyfish is most commonly found in Northern Australia but the syndrome has been described throughout the tropics, including Hawaii and northern Florida.
- The jellyfish is small (5 mm body with up to 100 cm long tentacles) and may not be noticed by the swimmer.
- Its venom is delivered via nematocysts and is thought to cause toxic modulation of neuronal sodium channels leading to excessive catecholamine release.
What is the clinical presentation of Irukandji Syndrome [2-8]?
- A mild sting (which can easily go unnoticed), a latent period of 10-45 minutes, then a rush of systemic symptoms
- Local erythema and piloerection may be seen in the shape of the bell or tentacles.
- Excruciating chest, back, and abdominal pain with significant muscle spasms
- Nausea, vomiting, and anxiety
- A sense of impending doom
- Severe hypertension is almost universally present initially
- Cardiogenic shock may follow initial hypertension and require pressor support
- Life-threatening sequelae include pulmonary edema, toxic cardiomyopathy, and intracranial hemorrhage, with fatalities reported
What is the treatment of Irukandji syndrome [2,6,9-11]?
- Vinegar (acetic acid) can be applied to envenomation site to inactivate nematocysts that have not yet fired. This is followed by careful removal of any retained tentacles.
- Pain management often requires large doses of opioids.
- Supportive care for nausea, vomiting, anxiety.
- Antihypertensives may be required; titratable agents such as esmolol are preferred as shock may develop later.
- About half of patients may require admission, with some requiring ICU level care.
- Intravenous magnesium salts have been proposed as an adjunct treatment for severe Irukandji syndrome but research to date is equivocal.
- Initially thought to be confined to the Northern Australian coast, Irukandji syndrome has been reported throughout the tropics.
- The syndrome begins with mild sting and a latent period followed by severe systemic symptoms of excruciating pain and sequelae of a catecholamine surge.
- First aid includes dousing in the site with vinegar (acetic acid) for 30 seconds and removing any tentacles.
- Treatment is ABCs, then pain control with IV opioids along with antiemetics, anxiolytics, and antihypertensives.
- May require admission and possible ICU level care for life-threatening complications.
This item was peer-reviewed on behalf of ACMT by Dr Eike Blohm, Dr Bryan Judge, and Dr Louise Kao.
Check out more of ALiEM’s ACMT Visual Toxicology Pearls
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- Blohm E & Brush E. Marine Envenomations. In: Goldfranks Toxicologic Emergencies 11th Edition; Eds Nelson L howland MA Lewin NA et al. McGraw Hill, New York, NY, 2019.
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- Australian Resuscitation Council. Envenomation: Jellyfish Stings (guideline 9.4.5) July 2010. https://resus.org.au/?wpfb_dl=41 Accessed April 2020
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- Rathbone J, Franklin R, Gibbs C, Williams D. Review article: Role of magnesium sulphate in the management of Irukandji syndrome: A systematic review. Emerg Med Australas. 2017 Feb;29(1):9-17. PMID: 27748058