Risk assessment for funnel-web spider bite

Note: Manage any big black spider bite initially as a funnel-web spider bite.

Funnel-web spider bites cause localised pain and bleeding associated with puncture marks at the bite site. In some cases, mild envenoming occurs with localised neuromuscular toxicity (paraesthesia, numbness, muscle fasciculations) and systemic symptoms. Severe envenoming is rare. See Clinical features of severe envenoming from funnel-web spider bite for clinical features of severe envenoming from funnel-web spider bite.

Bites from other big black spiders (eg the mouse spider [Missulena species]) may cause localised neurotoxicity and systemic symptoms. It is difficult to differentiate between types of big black spiders; therefore, manage any big black spider bite initially as a funnel-web spider bite. This is especially important in eastern Australia, where funnel-web spiders are endemic.

Table 1. Clinical features of severe envenoming from funnel-web spider bite
Body system	Features of severe envenoming
autonomic nervous system	cholinergic and adrenergic excess—generalised sweating, hypersalivation, lacrimation, piloerection, hypertension, bradycardia or tachycardia, miosis or mydriasis
neuromuscular system	paraesthesia (localised, distal and oral), muscle fasciculations (localised or generalised, commonly tongue fasciculations), muscle spasms
cardiovascular system	effects due to adrenergic excess—myocardial injury, hypertension, bradycardia, tachycardia
respiratory system	pulmonary oedema
central nervous system	agitation, anxiety, drowsiness, coma
nonspecific systemic symptoms	abdominal pain, nausea, vomiting, headache