A number of mygalomorph spiders cause
bites in Australia, including the funnel-web spiders (Hexathelidae, Atracinae: Hadronyche and Atrax) and mouse spiders (Actinopodidae: Missulena). There is ongoing debate about the significance of
bites by mouse spiders and the frequency of severe envenoming by funnel-web spiders. We conducted a prospective cohort study of definite
spider bites with expert spider identification and include the analysis of mygalomorph spiders here. Subjects were recruited prospectively from February 1999 to April 2003 from patients presenting to participating hospitals or contacting a state
poison information centre. Forty-nine cases of
bites by mygalomorph spiders were included: 16 were by funnel-web spiders, 13 by mouse spiders and 20 by other trapdoor spiders (Families Idiopidae and Nemesiidae). Of the 49
bites, 45 (92%) occurred on distal limbs (hands and feet). Local effects included severe
pain (53%),
puncture marks (61%) and
bleeding (27%), local redness (33%). Itchiness did not occur. The following were highly statistically associated with mygalomorph
spider bites compared to all other spiders (p<0.0001) circumstances (gardening at the time (likelihood ratio (LR) 7.9) and distal limb
bites (LR 2.0)) and early clinical features (presence of
puncture marks OR
bleeding (2.3), or severe
pain (2.0)). Of 16 funnel-web
spider bites, there were 10 cases with minor local effects, four with moderate envenoming (non-specific systemic or local neurotoxicity) and two with severe envenoming requiring
antivenom. In addition to local effects, mouse
spider bites caused local paraesthesia in three cases, local diaphoresis in one case and non-specific systemic effects in five cases, but not severe envenoming. True trapdoor
spider bites caused only minor effects. The data from a mixed species sample of funnel-web spiders confirms previous observations suggesting that only a small proportion of funnel-web
bites cause severe effects. Mouse
spider bites are unlikely to cause major envenoming but the clinical effects are consistent with neurotoxic
venom and are more severe than the trapdoor spiders.