To determine the types of spiders causing bites and the clinical effects of their bites in tropical Northern Territory (north of the town of Katherine). A prospective study of confirmed and suspected spider-bites and a retrospective analysis of data from a standardised, local database of spider- and snake-bites. Confirmed spider-bites were those in which there was a clear history of the bite, and the captured spider was identified by an arachnologist. Emergency department of a teaching hospital. SUBJECTS AND DATA SOURCE: All subjects with confirmed or suspected spider-bite presenting to the Emergency Department or referred from August 1999 to August 2000, or identified from the database. Thirty-four subjects had a confirmed spider-bite from an identified spider: 25 in the prospective group and nine in the retrospective group. The spiders were Sparassidae (huntsman spider) (12 bites), Missulena pruinosa (northern mouse spider) (7), Latrodectus (widow spider) (4), Araneidae (orb-weaver) (4), Salticidae (jumping spider) (4), Nemesidae (trapdoor spider) (1), Conothele (1) and Selenocosmia (whistling spider) (1). Clinical effects were local pain in 97% (severe in 29%), redness in 47% and swelling in 24% of cases. Systemic effects occurred in three victims, two of whom were bitten by M. pruinosa. There were no cases of confirmed necrotic arachnidism. None of the spider-bites resulted in severe effects. Compared with data from other parts of Australia, different species were involved and latrodectism was uncommon. Our study highlighted the importance of correctly identifying the spider species.

To examine the incidence, symptoms and treatment of red-back spider envenomation at a rural hospital. A retrospective review of all patients admitted to the intensive care unit of Alice Springs Hospital with red-back spider envenomation from 1 January 1991 until 31 December 1992. Thirty-two patients were identified, of whom 12 were Australian Aboriginals (35%). Mean time from bite to presentation was 21 hours. Twenty-six patients required antivenom. All patients responded well to therapy and adverse reactions to the antivenom were observed. Two antivenom recipients had had previous bites requiring treatment. Aboriginals received antivenom later than non-Aboriginals (27.0 h v. 16.5 h) and this delay was associated with more sweating and fever in Aboriginals. Red-back spider envenomation is common in Central Australia. Aboriginals and non-Aboriginals are equally at risk but later presentation is more common in Aboriginals who thereby suffer greater systemic symptoms. Antivenom use is safe and effective.