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Bites and stings

Prospective study of jellyfish stings from tropical Australia, including the major box jellyfish Chironex fleckeri

Gerard M O'Reilly, Geoffrey K Isbister, Paula M Lawrie, Greg T Treston and Bart J Currie

MJA 2001; 175: 652-655

Abstract - Methods - Results - Discussion - Acknowledgements - Conflict of interest - Reference - Authors' details
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Abstract

 Objective: To determine the immediate and delayed effects of jellyfish stings, and correlate these with microscopic identification of jellyfish nematocysts.
Design: Prospective study of patients presenting with jellyfish stings.
Participants and setting: 40 people presenting with jellyfish stings to the emergency department of a teaching hospital in tropical Australia between 1 August 1999 and 31 July 2000.
Main outcome measures: Clinical diagnosis (sting by Chironex fleckeri, "Darwin carybdeid" or other jellyfish, or "Irukandji" syndrome); clinical severity; delayed hypersensitivity; and sticky-tape sampling and microscopic identification of nematocysts.
Results: Patients were aged 2-50 years, with eight aged under 15 years; 23 were male. Presentations were consistent with C. fleckeri sting in 28 cases, Darwin carybdeid sting in five, and Irukandji syndrome in four. Sticky-tape sampling was done in 39 patients and was positive for C. fleckeri nematocysts in 23 and for non-C. fleckeri nematocysts in six, with nematocysts not detected in 10 (including all four with Irukandji syndrome). All microscopically confirmed C. fleckeri stings had typical clinical presentations. None of the stings were life-threatening, and no antivenom was given. Delayed hypersensitivity reactions were seen in 11 of the 19 patients (58%) followed up after stings positive for C. fleckeri nematocysts.
Conclusions: Although most jellyfish stings presenting to Royal Darwin Hospital were caused by C. fleckeri, severe envenomation was rare. There was a strong association between clinical features and sticky-tape identification of nematocysts. Delayed hypersensitivity was common after C. fleckeri stings.

Box jellyfish stings have historically been an important cause of mortality and morbidity in coastal tropical Australia.1-3 The most common cause of sting presentations to the Royal Darwin Hospital (NT) is the major box jellyfish Chironex fleckeri (Class Cubozoa; Order Chirodropidae)4-6 (Box 1A). It is responsible for most severe cases of jellyfish envenomation.1-4 Clinical manifestations include immediate local pain with visible linear tentacle marks and, in severe stings, systemic effects with cardiorespiratory arrest possible within minutes.1-4,6-8 However, fatalities are rare, and the clinical spectrum is not evident from published case reports, which mostly present fatal or near-fatal cases. In addition, it is not clear whether delayed hypersensitivity, which has been reported after other jellyfish stings, is a feature of C. fleckeri stings.1

The "Irukandji" syndrome has been associated with stings by Carukia barnesi (Class Cubozoa; Order Carybdeidae)9,10 (Box 1C), although other jellyfish may cause a similar syndrome.11 C. barnesi has rarely been found in the Northern Territory (P Alderslade, Curator of Coelenterates, Museum and Art Gallery of the Northern Territory, Darwin, NT, personal communication), and the Irukandji syndrome is less common than in far north Queensland.10,11 Other jellyfish species appear to cause some stings in the Darwin region.1,4 These include the "Darwin carybdeid",1 a four-tentacled jellyfish larger than C. barnesi, which appears to cause less severe skin damage than C. fleckeri.

We conducted a prospective study of all jellyfish-sting presentations to Royal Darwin Hospital over 12 months in 1999 and 2000. Our aim was to determine the immediate and delayed effects of all marine stings, and to correlate these with microscopic identification of jellyfish nematocysts using the sticky-tape sampling technique.6

Methods The study included all patients who presented to the Royal Darwin Hospital after a jellyfish sting between 1 August 1999 and 31 July 2000. The study was approved by the Joint Institutional Ethics Committee of the Royal Darwin Hospital and the Menzies School of Health Research.

Patients were assessed and treated in the Emergency Department according to the Royal Darwin Hospital protocol12 (Box 2). Clinical and demographic details were entered prospectively, along with details of hospital management, on a standardised form. Details included investigations (eg, electrocardiography [ECG]), type and effect of analgesia (topical [ice], oral [eg, aspirin or codeine], or parenteral [morphine or pethidine]) and whether C. fleckeri antivenom was administered.

The clinical diagnosis was classified as typical or not typical of C. fleckeri sting according to known features (immediate and persistent local pain, linear sting marks and absence of generalised pain, which is seen in Irukandji syndrome).1,3,11

Sticky-tape sampling

During the initial presentation, the sting site was sampled for nematocysts using the sticky-tape technique developed in Darwin.6 Transparent sticky tape was applied to the site and then transferred to a microscope slide for examination at x 100 to x 400 magnification. This allows nematocysts of C. fleckeri to be distinguished from those of other jellyfish on the basis of morphology (Box 1B and 1D). Presence of C. fleckeri or other jellyfish nematocysts was determined by one of the authors (P M L) and verified by another (B J C).

Follow-up

 We telephoned patients about three weeks after initial presentation to ask about persistent or delayed effects, especially emergence of a pruritic rash at the site of the initial sting.

Results Forty patients presented to Royal Darwin Hospital with jellyfish stings in the 12-month study period. They were aged two to 50 years (median, 21 years), with eight aged under 15 years; 23 were male. Seasonal variation in stings is shown in Box 3.

Of the 40 stings, 28 (70%) were clinically typical of C. fleckeri, and 12 (30%) were not typical. Four of the latter were consistent with Irukandji syndrome (minimal local erythema, and delayed systemic symptoms, especially pain), and five with Darwin carybdeid sting (less severe skin pain and markings, with some "overlap" Irukandji features, such as abdominal pain). A typical C. fleckeri sting is shown in Box 4A.

Sticky-tape sampling

Sticky-tape sampling was done in 39 patients and was positive for nematocysts in 29 — C. fleckeri in 23 and carybdeid-appearing nematocysts in six. Sampling was negative for nematocysts in 10 patients, including all four with Irukandji syndrome. Correlation between microscopic findings and clinical presentation is shown in Box 5. All microscopically confirmed C. fleckeri stings had typical clinical presentations. Of the six patients with carybdeid-appearing nematocysts, five had presentations consistent with Darwin carybdeid envenomation, while one was more consistent with C. fleckeri.

Management

 None of the 40 patients had documented arrhythmias on ECG, or pulmonary oedema. None was treated with pressure-immobilisation bandages or C. fleckeri antivenom, and there were no deaths. Of the 23 patients with stings positive for C. fleckeri nematocysts, one required parenteral analgesia and nine oral analgesia. In five, pain responded to topical ice alone, and eight required no pain relief. None of these patients required admission. Maximum length of tentacle marks was 5 m, followed by 4 m; both patients had severe local pain. Three of the patients with Irukandji syndrome and one stung by an unidentified jellyfish (no nematocysts detected on sticky-tape sampling) required admission for analgesia.

Follow-up

 Twenty-nine patients were followed up, including 19 whose stings were positive for C. fleckeri nematocysts. Of these 19, 11 (58%) had delayed hypersensitivity reactions. These comprised an itchy red maculopapular rash dotted along the initial tentacle contact points consistent with papular urticaria, occurring 7-14 days after first presentation (Box 4B). These reactions resolved spontaneously in seven patients and after treatment with oral antihistamine and topical corticosteroid cream in four.

Discussion This is the largest prospective study of C. fleckeri stings to date. Most previously published cases describe fatal or near-fatal stings, and some authors quote mortality rates up to 20%.13 Our study does not support this high mortality rate and showed that most stings were not severe, consistent with previous Northern Territory findings.5-7

Although most C. fleckeri stings are minor and not life-threatening, the potential exists for severe systemic envenomation and even death. It is a concern that, despite considerable public education, eight of our cases were in children. The last 10 deaths from C. fleckeri envenomation in the Northern Territory were all of children, most recently a three-year-old girl from a remote Aboriginal community in February 1996.4 In January 2000, a five-year-old boy died soon after a jellyfish sting near Yarrabah, in north Queensland, presumed to be from C. fleckeri.14

In the past, considerable attention has focused on the use of antivenom in C. fleckeri envenomation.3,8,15-17 Indications have been cardiac arrest and arrhythmias, analgesia or cosmesis, although evidence supporting the efficacy of antivenom remains limited.7 None of our patients received antivenom, as none had cardiac toxicity, and severe local pain was controlled with appropriate analgesia. Nevertheless, it is crucial that antivenom is available for early use in life-threatening situations with arrhythmias or cardiorespiratory arrest.

None of our patients had pressure-immobilisation bandages applied. These bandages are not recommended in the Northern Territory, as they potentially increase nematocyst discharge and are unlikely on theoretical grounds to prevent venom absorption.7,12,18

Delayed skin eruptions have been reported after jellyfish stings, although C. fleckeri has not been specifically implicated.19-21 These eruptions typically occurred at the site of the original sting after five days or more, and were pruritic and painless.1 Their histological features were generally consistent with delayed (type IV) hypersensitivity reactions.20 They are likely to be a response to retained foreign material, such as nematocyst thread or other cellular substances injected into the dermis, but specific antigens have not been identified.

In our study, over half the patients followed up after stings positive for C. fleckeri nematocysts had delayed skin eruptions clinically resembling papular urticaria, similar to those reported after other jellyfish stings.19-21 This confirms that delayed cutaneous hypersensitivity reactions are common after C. fleckeri stings. Corticosteroid cream, with or without systemic antihistamines, may help relieve symptoms of delayed reactions.1,7

Correlation of sticky-tape sampling with clinical presentation suggests that there were no false-positive identifications of C. fleckeri nematocysts. The false-negative rate is unknown. However, as the test was negative for nematocysts in only three cases that appeared clinically typical of C. fleckeri envenomation, correlation with clinical findings appears good.

While all the non-C. fleckeri nematocysts detected were carybdeid in appearance, degenerate C. fleckeri nematocysts may sometimes appear similar. Further description and classification is needed of the Darwin carybdeid and other local jellyfish yet to be identified. Clinical features of most of the carybdeid nematocyst-positive stings differed from those of both C. fleckeri stings and the Irukandji syndrome. The Darwin carybdeid appears to cause local pain from tentacle marks, but this pain is less severe than in C. fleckeri stings. The Darwin carybdeid also causes some "overlap" systemic symptoms, similar to those of a mild Irukandji syndrome. Two earlier stings with these features were confirmed to be caused by the Darwin carybdeid through capture and examination of the jellyfish, as well as microscopic identification of nematocysts1 (Currie BJ, unpublished data).

Finally, although life-threatening envenomation is uncommon, we should continue to pursue public education and prevention policies vigorously. Deaths from severe C. fleckeri envenomation will inevitably occur while people, especially children without protective clothing, enter tropical waters in Australia.

Acknowledgements

We would like to acknowledge support from the Cooperative Research Centre for Aboriginal and Tropical Health; from the National Health and Medical Research Council Centre of Clinical Excellence grant to the Northern Territory Clinical School, Royal Darwin Hospital; and the staff of the Emergency Department, Royal Darwin Hospital, particularly Carole Mansfield and Marg St Leone. We would also like to acknowledge Phil Alderslade (Northern Territory Museum, Darwin) for assistance and for the photograph of the Darwin carybdeid.

Conflict of interest

There was no specific funding for this study and no conflict of interest.

References
  1. Williamson JA, Fenner PJ, Burnett JW, Rifikin JF. Venomous and poisonous marine animals. 1st ed. Sydney: University of New South Wales Press, 1996.
  2. Williamson JA, Callanan VI, Hartwick RF. Serious envenomation by the northern Australian box-jellyfish (Chironex fleckeri). Med J Aust 1980; 1: 13-15.
  3. Williamson JA, Le Ray LE, Wohlfahrt M, Fenner PJ. Acute management of serious envenomation by box-jellyfish (Chironex fleckeri). Med J Aust 1984; 141: 851-853.
  4. Currie BJ. Clinical toxicology: a tropical Australian perspective. Ther Drug Monit 2000; 22: 73-78.
  5. Currie BJ, Khanh DM, Alderslade P, et al. Jellyfish envenomation in the Northern Terrritory of Australia. Toxicon 1992; 30: 501.
  6. Currie BJ, Wood YK. Identification of Chironex fleckeri envenomation by nematocyst recovery from skin. Med J Aust 1995; 162: 478-480.
  7. Currie B. Clinical implications of research on the box-jellyfish Chironex fleckeri. Toxicon 1994; 32: 1305-1313.
  8. Lumley J, Williamson JA, Fenner PJ, et al. Fatal envenomation by Chironex fleckeri, the north Australian box jellyfish: the continuing search for lethal mechanisms. Med J Aust 1988; 148: 527-534.
  9. Barnes JH. Cause and effect in Irukandji stingings. Med J Aust 1964; 1: 897-904.
  10. Little M, Mulcahy RF. A year's experience of Irukandji envenomation in far north Queensland. Med J Aust 1998; 169: 638-641.
  11. Fenner PJ, Williamson JA, Callanan VI, Audley I. Further understanding of, and a new treatment for, "Irukandji" (Carukia barnesi) stings. Med J Aust 1986; 145: 569-574.
  12. Currie B. Box-jellyfish in the Northern Territory. N T Dis Control Bull 1998; 5: 12-14.
  13. Guenin DG, Auerbach PS. Trauma and envenomations from marine fauna. In: Tintinalli JE, Ruiz E, Krome RL, editors. Emergency medicine — a comprehensive study guide. 4th ed. New York: McGraw-Hill, 1996: 868-873.
  14. Lill J. Fatal sting. Box jellyfish kills boy, 5. The Cairns Post 2000 Jan 25: 1.
  15. King GK. Acute analgesia and cosmetic benefits of box-jellyfish antivenom. Med J Aust 1991; 154: 365-366.
  16. Beadnell CE, Rider TA, Williamson JA, Fenner PJ. Management of a major box jellyfish (Chironex fleckeri) sting. Lessons from the first minutes and hours. Med J Aust 1992; 156: 655-658.
  17. Holmes JL. Marine stingers in far north Queensland. Australas J Dermatol 1996; 37 Suppl 1: S23-S26.
  18. Pereira PL, Carrette T, Cullen P, et al. Pressure immobilisation bandages in first-aid treatment of jellyfish envenomation: current recommendations reconsidered. Med J Aust 2000; 173: 650-652.
  19. Reed KM, Bronstein BR, Baden HP. Delayed and persistent cutaneous reactions to coelenterates. J Am Acad Dermatol 1984; 10: 462-465.
  20. Pierard GE, Letot B, Pierard F. Histologic study of delayed reactions to coelenterates. J Am Acad Dermatol 1990; 22: 599-601.
  21. Burnett JW, Cobbs CS, Kelman SN, Calton GJ. Studies on the serologic response to jellyfish envenomation. J Am Acad Dermatol 1983; 9: 229-231.
(Received 20 Apr, accepted 13 Aug, 2001)

Authors' details

Royal Darwin Hospital, Darwin, NT.
Gerard M O'Reilly, MB BS, Emergency Registrar; currently, Emergency Registrar, Alfred Hospital, Melbourne, VIC.
Geoffrey K Isbister, BSc, MB BS, Emergency Registrar; currently, Toxicology Registrar, Department of Clinical Toxicology and Pharmacology, Newcastle Mater Hospital, Newcastle, NSW.
Greg T Treston, DTMH, DIMCRCS, FACEM, Director of Emergency Department; currently Consultant, Emergency Department, John Flynn Hospital, Tugun, QLD.

Menzies School of Health Research, Darwin, NT.
Paula M Lawrie, BSc, Technical Officer.
Bart J Currie, FRACP, FAFPHM, DTMH, Head of Tropical Medicine and International Health Unit; and Professor in Medicine, NT Clinical School, Darwin, NT.

Reprints will not be available from the authors.
Correspondence: Professor B J Currie, Tropical Medicine and International Health Unit, Menzies School of Health Research, PO Box 41096, Casuarina, NT 0811. bartATmenzies.edu.au

©MJA 2001
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1: Common Northern Territory jellyfish and their nematocysts
     
Chironex fleckeri
A.
Image A
 
B.
Image B
Nematocysts from C. fleckeri (original magnification, x 400; sticky-tape preparation; no stain).
"Darwin carybdeid"
C.
Image C
D.
Image D

"Darwin carybdeid" nematocyst (original magnification, x 1000; eosin stain).

   
Nematocysts from C. fleckeri are usually elongated ellipses (cigar-shaped), while those from carybdeid (four-tentacled box-jellyfish) species are usually less elongated and more lemon-shaped or round.
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2: Protocol for hospital treatment of Chironex fleckeri stings in the Northern Territory

1. If necessary, attend to airway, breathing and circulation and give oxygen.
2. Apply vinegar to the stings for at least 30 seconds to inactivate remaining nematocysts.
3. If patient is unconscious or has life-threatening cardiac or respiratory decompensation or significant arrhythmia, administer at least one ampoule of antivenom intravenously (20 000 units per ampoule, diluted 1:10 with an isotonic crystalloid solution such as Hartmann's solution or isotonic saline, given over 5-10 minutes). In a life-threatening situation where response remains inadequate, up to three ampoules may be given consecutively.
4. Cardiopulmonary resuscitation should be continued in a patient with ongoing cardiac arrest until after further therapy with antivenom (at least six ampoules total dose if available) and consideration of cardioactive drugs.
5. For non-life-threatening stings (no cardiac or respiratory decompensation), use ice-packs for initial pain relief, together with oral or parenteral analgesia if necessary (pethidine, 1 mg/kg up to 50 mg adult dose initially, or morphine, 0.1 mg/kg up to 5 mg initially, but can be repeated). For pain not relieved by ice-packs and narcotic analgesia, administer one ampoule of antivenom intravenously as above.

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3: Jellyfish sting presentations to Royal Darwin Hospital, 1999-2000

Figure 3

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4: Chironex fleckeri stings
A.
Image A
Severe sting on Day 2.
  		  B.
Image B
Hypersensitivity reaction seen 10 days after a sting.
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5: Correlation between clinical presentation and nematocyst identification in 39* jellyfish stings
       
Nematocyst appearance
Presentation Chironex fleckeri Other jellyfish† Not detected
Typical of C. fleckeri (n = 27)* 23 1 3
Not typical 0 5 7
 "Irukandji" syndrome (n = 4) 0 0 4
 Other (n = 8) 0 5 3
* Nematocyst sampling was not performed in one patient with a typical C. fleckeri presentation.
† All non-C. fleckeri-appearing nematocysts were consistent with carybdeid nematocysts, although degenerate C. fleckeri nematocysts may sometimes look similar.
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