The Amazing and Bizarre Discovery of Irukandji Syndrome : Emergency Medicine News

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Toxicology Rounds

The Amazing and Bizarre Discovery of Irukandji Syndrome

Gussow, Leon MD

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Emergency Medicine News 27(4):p 44-45, April 2005.

    Published more than 40 years ago, “Cause and Effect of Irukandji Stingings” remains one of the most amazing and bizarre papers ever to appear in the medical literature. (Med J Australia 1964;1(24):897.)

    Table 1:
    Signs and Symptoms of Irukandji Syndrome

    The author, Dr. J.H. Barnes, set out to answer a question that, while seemingly simple, had stumped investigators for more than two decades: What marine organism causes Irukandji syndrome, a distinct illness that occasionally struck waders and divers off the coast of northern Australia? This syndrome typically began with a relatively mild stinging sensation — no worse than that of a bee — on a part of the body that was underwater. Sometimes the victim would experience no sting at all, and weal formation that was typical of attacks by some known species of jellyfish did not occur.

    Eschewing animal models and laboratory studies, Barnes proceeded directly to human experimentation

    After a delay of around 10 to 50 minutes, this was followed by severe constitutional symptoms: excruciating back pain, generalized muscle cramping, spasm, nausea and vomiting, anxiety (often described as a “feeling of doom”), diaphoresis, tachycardia, and markedly elevated blood pressure (as high as 280/180 mmHg). These manifestations were extremely distressing to victim and treating physician alike, but generally resolved by the following day.

    In the course of previous studies, the usual suspects — the box jellyfish, the Portuguese man-o‘-war — were rounded up before being exonerated. But Barnes, by carefully searching sea water at the site of a recent attack, isolated a previously unknown type of jellyfish. It was approximately the size of a man's thumb, translucent, and shaped roughly like a cube trailing four tentacles, one at each corner. Shortly thereafter, a lifeguard scooped up a second specimen. But the question remained: Was this tiny new species actually the cause of Irukandji syndrome? (It was named, by the way, for an aboriginal tribe that had lived near the site of most attacks.)

    Human Experimentation

    Here's where things became interesting. Eschewing animal models and laboratory studies (not to mention all common sense), Barnes took the two specimens, and proceeded directly to human experimentation. He related his methods in the paper:

    Table 2:
    Differential Diagnosis of Irukandji Syndrome

    “The first Carybdeid was applied to an adult (J.B.), and to a boy, aged nine years (N.B.). A robust young life-saver (C.R.) volunteered to test the second specimen, of similar size to the first. The jellyfish was placed in contact with the inner surface of the upper arm of each volunteer. The effects were not long in coming.

    Carukia barnesi was named after its reckless discoverer, J.H. Barnes, MD.

    “The lad reported mild abdominal pain twelve minutes after being stung, and two minutes later declared he had an ache in both armpits, that abdominal pain was worsening rapidly, and that his back was hurting. Within 20 minutes, the two adults noted aching in both axillae, followed almost immediately by backache and by discomfort around the lower ribs anteriorly. Back pain was maximal in the sacral area, deep and “boring” in nature.

    “Severe abdominal pain, the most constant feature of the Irukandji syndrome, was well established in all cases within 30 minutes. … Subjects were seized with a remarkable restlessness, and were in constant movement. … As the pains increased, initiative was notably depressed, and cerebration, though accurate, was decidedly sluggish. … Palpation of painful areas, now including arms and legs, showed muscle groups in tonic contraction, little short of spasm. This possibly explains the peculiar postures noted, for extremes of flexion and extension were avoided, and the volunteers adopted a stance, which I can best liken to that of an infant with a full nappy.”


    Let us interrupt here with a description of the pathophysiology and treatment of Irukandji syndrome, as it is understood today. Although it still has not been characterized completely, the toxin of the Irukandji jellyfish (since named Carukia barnesi after its reckless discoverer) seems to act as a presynaptic sodium channel agonist, markedly enhancing the release of catecholamines. This causes manifestations somewhat similar to those of pheochromocytoma, including diaphoresis, vomiting, anxiety, chest and abdominal pain, and often severe hypertension. Sequelae can include reversible left ventricular dysfunction and pulmonary edema (sometimes delayed for 10 hours or more after envenomation).

    Creatine phosphokinase can be elevated. Although this often represents the skeletal muscle (MM) fraction, cardiac (MB) enzymes also may rise. While death is rare, there has been a recent report of a 58-year-old man taking warfarin who developed a fatal intracerebral bleed after being stung by C. barnesi. (Med J Australia 2002;177:362.)

    Table 3:
    Treatment of Irukandji Syndrome

    We rejoin to Dr. Barnes and his two volunteers, who are speeding to the hospital:

    “During the 20 minutes drive to Cairns, the victims were in considerable distress, heightened, it seemed by the necessity to remain seated. All had abdominal and back pain, pain in the anterior chest wall with some difficulty in breathing, and diffuse aches in muscles and joints. … N.B. felt very cold and was shivering violently.

    “Forty minutes after the stinging, the abdominal musculature of the three subjects was in unrelenting spasm, so rigid as to warrant fully the term “board-like.” … Undoubtedly, the advent of coughing and retching marked the peak of misery for the two adults. Each spasm increased the gripping pains in the chest and abdomen, and as these eased, the cycle was repeated.”

    Fortunately, all subjects survived the trip, felt considerable relief after being treated with opiate analgesics, and recovered completely within 24 hours.

    Dr. Barnes proves that Steve Erwin (the Crocodile Hunter) is not an aberration. There are many wonderfully loopy characters who have contributed to our understanding of Australian natural history. So let's raise a pint of Foster's in honor of Barnes, his 9-year-old son (N.B.), and that robust young life-saver.

    © 2005 Lippincott Williams & Wilkins, Inc.