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 Obje ctive: To determine the immediate and delayed effects of jellyfish stings, and correlate these with microscopic identification of jellyfish nematocysts. Design: Prospective study of patients present ing with jellyfish stings. Particip ants 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 o utcome measures: Clinical diagnosis (sting by Chironex neceen, "Darwin carybdeid " or other jellyfish,'or "lruk andji" syndrome); clinical sever ity; delayed hypersensitivity; and sticky-tape sampling and microscopic identification of nematocysts. Res ults: Patients were aged 2-50 years, with eight aged under 15 years; 23 were male. Presentati ons were consistent with C. fleckeri sting in 28 cases, Darwin carybdeid sting in five, and lrukandil 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 lrukandji 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. Concl usions: 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. B ox JELLY fi SH STL,\; GS have historically been an important cause of mortality and morbidity in coastal tropical Aus- tra lia.t-! Th e most commo n cause of sting presentations to the Royal Darwin Hospital (NT) is the m ajor box jellyfish Ch iranex fiecheri (Class CUbOZ03; Order Chirodropidae j- e (Box IA). It is respon- sible for most severe cases of jellyfish en ven om ation .t-' Clinical manifesta- tions include immed iate loca l pai n with visible linear tentacle marks and, in severe stings, systemic effects wit h car- diore spi rator y arrest possible with in minures.t-s-s-e However, fatalities are rare, and the clinical spectrum is not evi- den t from published case rep ort s, which mostly present fatal or near- fatal cases. In addition, it is not clear wheth er delaye d hypers ens itivity, which ha s bee n reported after o the r jellyfish stings, is a featur e of C. jleckeri stings.' T he "Iruka ndji" syndrome has been associated with stings by Car ukia barnesi (Class Cubozoa; Order Cerybdeidaejv-" (Box IC), althou gh ot her jellyfish may cause a similar syndrome. II C. bamesi has rarely b een foun d in the Northern Ter ritory (P Alder-slade, Curator of Coelenterates, Museum and Art Gallery of the No rth ern Territory, Darwin, NT , personal commu nication), and the Iro kandji syndrome is less common than in far nort h Queensland.w-!' Other jellyfish species appear to cause some stings in the Darwin region.i.s These include the " Darwin carybd eid";' a fou r- tentacle d jellyfi sh large r th an C. barn esi, which appears to cause less severe skin damage than C. fleckeri, We conducted a prospective study of all jellyfish -sting presentations to Royal D arwin Hospital over 12 m ont hs in 1999 and 2000 . Our aim was to deter- mine the immediate and delayed effect s of all mar ine stings, and to correlate these with microscopic identification of jellyfish nem atocysts usi ng the sticky- tape samp ling technique." METHODS Royal Darwin Hospital , Darwin, NT. Gerard M O'Reilly, MB BS. Emergency,Registrar; currently. Emergency Reyistrar. Alfred Hospital. Melbourne. VIC. Geo ffr ey K Isbister, BSc. MS BS. Emergency Registrar; currently. Toxicology Registrar, Department of Clinica l Toxicology and Pharmacology, Newcastle Mater Hospital, Newcastle, NSW. Greg T Treston, DTMH, DIMCRCS. FACEM. Directo r of Emergency Department: cur rently Consu ltant. Emergency Department. John Flynn Hospital, Tugun, OLD. Menzi es Sc hool of Health Re sean:h, Darwin , NT. Paula M lawrie, SSe. Technical Officer. Bart J Cu rrie , FRACP. FAFPHM, DTMH, Head of Tropical Medicine and International Health Unit and Professo r in Medicine. NT Clin ical School . Darwin , NT Reprints will not be available from the authors, Correspond ence Professor B J Currie , Tropical Medicine and Internafional Health Unit. Menzies School ot Health Research. PO Box 41096, Casuarina. NT 081 1. bart@ menzies .edu,au 65 2 Th e study included all patients who pre- sented to the Royal Darwin Hospital after a jellyfish sting between I August 1999 and 31 July 2000 . Th estudy was app roved by th e Joint Institutional Ethics Comm ittee of the Royal Darwin Hospi tal and the Menzies School of Health Research. Patients were assessed a nd treated in the Emergency Department according to the Royal Darwin Hospital prorocct" (Box 2). Clinical an d demographic details were entered prospectively, along with details of hospital management, on MJA Vol 175 3/17 December 2001