Laboratories, Melbourne, Australia. The initial dose is one ampoule (diluted 1:5 to 1:10 in isotonic
crystalloid; dilution with water is not recommended) administered intravenously over 5 minutes, or three
ampoules intramuscularly. This has been administered successfully over the years by members of the
Queensland Surf Life-Saving Association and the Queensland Ambulance Transport Brigade. Although the
antivenom is prepared by hyperimmunizing sheep and adverse reactions reported to date have been rare and
mild, the prudent physician is always prepared to treat anaphylaxis or serum sickness. It cannot be
overemphasized that the timely administration of antivenom can be lifesaving. In addition to its lifesaving
properties, the early administration of antivenom may markedly reduce pain and decrease subsequent skin
scarring. Antivenom administration may be repeated once or twice every 2 to 4 hours until there is no further
worsening of the skin discoloration, pain, or systemic effects. A large sting in an adult may require the initial
administration of up to three ampoules IV. The antivenom may also used to neutralize the effects of a
Chiropsalmus envenomation. The antivenom should be stored in a refrigerator at 2
o
to 10
o
C and must not be
frozen. The concomitant administration of a glucocorticoid (such as hydrocortisone 200 mg intravenously), is
often recommended for its antiinflammatory activity but is no substitute for the administration of antivenom.
Even with successful treatment, skin irritation may persist for months, marked by discolored striae,
intermittent desquamation, and pruritus. Burnett and Calton discovered that verapamil can prolong the life of
mice challenged with box-jellyfish, sea nettle, or Portuguese man-of-war venom. It was considered to be
inactive or deleterious in anaesthetized laboratory pigs envenomed with box-jellyfish venom. To date,
extrapolation of these data to the human condition is as yet untested. Although there is logic to using
verapamil from a theoretical pharmacological perspective (venom affects calcium influx through voltage-
dependent channels), the suitability of using verapamil as an adjunct to therapy in humans has been
questioned because of the perceived problem of administering a hypotensive agent during an episode of
cardiac decompensation. Further information and opinions about the use of verapamil will undoubtedly be
forthcoming.
Irukandji.
Carukia barnesii, the carybdeid jellyfish known as "Irukandji," is a small (1 to 2.5 cm
across the bell) translucent jellyfish with four thin nematocyst-covered tentacles (2.5 to 4.5 cm in length at
rest, and up to 65 cm extended) found off the coast of northern Australia in both inshore and open waters.
Most stings occur near shore and during the afternoon. Because the jellyfish tend to aggregate, victims often
present in clusters. After causing a severe immediate skin reaction characterized by pain and erythema
without wheal formation, the venom may induce muscle pain and spasm, back pain, abdominal pain,
parasympathetic dysautonomia, respiratory difficulty, headache, nausea, and vomiting, which progress to
profound weakness and collapse.40 Localized piloerection and sweating have been reported. Generally the
discomfort remits in 6 to 24 hours; however, it occasionally recurs. The "Irukandji syndrome" presupposes
massive catecholamine release, with abdominal and chest pain, vomiting, diaphoresis, hypertension (diastolic
blood pressure to 140 mm Hg), tachycardia, severe pulmonary edema, and hypokinetic heart failure. This
resembles what might be seen with a pheochromocytoma. Papilledema and coma in a child have been
described. Although the systemic syndrome can be quite distinctive, there can be minimal cutaneous signs of
envenomation. A recent death in a U.S. citizen may be due to this species. It is interesting to note that many
Irukandji-like stings occur inside "stinger enclosures" (bathing nets) designed to exclude Chironex fleckeri.
Other carybdeid medusae that envenom with lesser severity include the jimble (Carybdea rastoni) and fire
jelly (Tamoya haplonema). The morbakka is a stinging creature that resembles the Irukandji but is larger. The
bell, which measures up to 16 by 12 cm, is covered with clumps of nematocysts and may be as dangerous to
handle as the meter-long tentacles. This animal may have been previously misidentified as Tamoya.
Chrysaora (Sea Nettle). Sea nettles (such as Chrysaora quinquecirrha and Cyanea capillata) are
considerably less lethal animals and can be found in both temperate and tropical waters, particularly in
Chesapeake Bay, where they are found in seasonal "plague" proportions.
Not as dangerous as the Indo-Pacific
box-jellyfish, they are still capable of inducing a moderately severe sting. Chrysaora quinquecirrha and
similar species carry a proteinaceous venom that contains at least seven enzymes, with at least one antigenic
and thermolabile component that is cardiotoxic, neurotoxic, and dermatonecrotic. The venom also contains
histamine, histamine releasers, prostaglandins, serotonin, and kininlike factors; the last mentioned have also
been found in venoms of Chironex fleckeri and Physalia physalis. Large intradermal injections of crude sea
nettle venom in normal saline produced immunosuppression (T cells) for several days, which was
