![]() A recent prospective study has suggested that many patients would benefit from antivenom treatment because untreated patients had persistent pain and many were unable to sleep because of it 4Īlthough intramuscular antivenom has been recommended and used for over 40 years there are concerns that it is less effective than intravenous antivenom. Pressure bandaging is contraindicated in redback spider bites. There has been controversy over the management of redback spider bites, particularly who should be treated with antivenom and the route of administration. The diagnosis is based on the history, but can be difficult in young children and infants who may present with undifferentiated pain or distress. There have been no deaths since the 1950s. The effects last about 1-4 days with almost all cases resolving within one week. Numerous other systemic effects are reported less commonly (see box). Common nonspecific effects include nausea, lethargy, malaise and headache. Local erythema is common and local diaphoresis occurs in about a third of cases. These spiders are small and rarely leave fang marks or cause local bleeding. Pain increases over about an hour and may radiate proximally to the limb or less commonly the trunk. The bite may not be felt or may only be an initial irritation or discomfort. Redback spider bites occur in the warmer months and peak between January and April.Įnvenoming by redback spiders is characterised by local, radiating and regional pain which may be associated with local and regional diaphoresis, non-specific systemic features, and less commonly other autonomic or neurological effects (see box). Most bites are by the larger female spider and in most cases the spider is recognised by the patient if it is seen. 4Redback spiders live in dry or dark areas and commonly cause bites when people put on shoes or when they move outdoor furniture, bike helmets, firewood or pot plants. Severe and persistent pain occurs in a half to two-thirds of cases and may be severe enough to prevent sleep in about a third of cases. Redback spider bites are the commonest cause of significant envenoming in Australia. Diagnosis and investigation in patients with ulcers must focus on important causes of necrotic ulceration including infectious, inflammatory, vascular and neoplastic conditions. ![]() It is important to distinguish patients presenting with clinical effects (usually skin lesions or ulcers) that have been attributed to a spider bite and patients with a clear history of a definite spider bite. A recent series of suspected white-tail spider bites found other causes when appropriately investigated. 2Current evidence suggests that spider bites are very unlikely to cause necrotic lesions and such cases presenting as suspected spider bites should be thoroughly investigated for other causes. The bites caused pain in only 21% of patients, pain and a red mark for 24 hours in 35%, or a persistent red mark and associated itchiness, pain or lump lasting for about seven days in 44%. In a prospective study of definite white-tail spider bites there were no cases of necrotic ulcers. Necrotic arachnidism, or more commonly in Australia white-tail spider bite, has become an entrenched diagnosis despite the lack of evidence that spider bites cause necrosis or ulcers in Australia. If the patient has not been bitten by a big black spider or a redback spider they can be reassured and no further treatment is required. All other spiders in Australia cause minor effects. Redback spiders are fairly easy to identify and their bites do not cause rapidly developing or life-threatening effects but many cause significant pain and systemic effects. Patients bitten by big black spiders must be managed as having suspected funnel-web spider bites until there are no signs of envenoming after four hours. Big black spiders are any large black-looking spiders that may be a funnel-web spider. Spider bites are best considered in three medically relevant groups: big black spiders, redback spiders and all other spiders. Other local effects include fang marks or bleeding (larger spiders), erythema or red marks (about two-thirds of cases) and itchiness. 1Pain or discomfort occurs in all spider bites. Moderate to severe envenoming resulted almost exclusively from redback spiders and rarely funnel-web spiders. ![]() In a study of 750 definite spider bites the majority caused only minor effects and did not require treatment in a healthcare facility. A definite spider bite is where there is evidence of a spider biting (effects), the spider is seen at the time and it is then identified by an expert. There is ongoing misinformation about the effects of suspected spider bites, because past information has been based on circumstantial evidence. Spider bites are a common problem with numerous calls being made to poisons information centres annually.
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