Hartman and Sutherland 1984: 9 Atrax sp. bites. Identification: A. robustus 6/9, A. formidabilis 2/9, A. bermagui 1/9.
Dieckmann et al. 1989: 3 Hadronyche sp. bites. Identification: H. versuta 1/3, H. infensa 1/3, H. cerberea 1/3.
Fisher et al. 1980: 2 Atrax sp. bites. Identification: A. robustus 2/2.
Sutherland 1992: 3 Funnel-web spider bites. Identification: A. robustus 1/3, H. cerberea 1/3, Atrax sp. 1/3.
Harrington et al. 1999: 5 cases of Hadronyche sp. bites. Identification: morphological (H. infensa; 3/5 male, 2/5 female).
Miller et al 2000: 5 cases of Hadronyche sp. bites. Identification: morphological (male H. cerberea 2/5, male H. formidabilis 1/5), male H. infensa 1/5, male Hadronyche sp. 1/5).
Signs & symptoms
Experimental and clinical observations suggest that the major systemic effects of envenoming are caused by endogenous catecholamines and acetylcholine, which are released in response to Atrax sp. and Hadronyche sp. venom. As these are transmitters of the sympathetic, parasympathetic and somatic nervous systems, the resulting clinical symptoms of envenoming are dealt with in the section "Neurological effects".
Severe local pain, local erythema (Hartman and Sutherland 1984, Sutherland 1983).
Local pain (Miller et al. 2000).
Local pain 4/5 (Harrington et al. 1999).
A substantial proportion of the envenoming symptoms caused by Atrax sp. and Hadronyche sp. are explained by the fact that these venoms affect the autonomic nervous system and neuromuscular conduction (Sutherland 1983). The evenoming syndromes caused Atrax sp. and Hadronyche sp. bites are indistinguishable (Miller et al. 2000). They appear to possess a high specificity for primates, including humans. For example, atraxotoxin induces the release of catecholamines in macaques (Duncan et al. 1980). Both parts of the autonomic nervous system and the somatic nervous system are stimulated. This results in cholinergic effects (vomiting, profuse sweating, hypersalivation), adrenergic effects (arterial hypertension, tachycardia, cardiac arrhythmias) and effects on the skeletal musculature (fasciculations, spasms). When severe envenoming is induced in macaques, they develop intracranial hypertension and non-cardiogenic pulmonary oedema. These types of effects may also play a role in humans, especially in fatal cases of envenoming.
At the early stage of envenoming, perioral numbness, tongue spasms. Nausea, vomiting, abdominal pain, sweating, hypersalivation and hyperlacrimation, dyspnoea. Muscle fasciculations and spasms, local and generalised. Confusion, coma. Arterial hypertension, pulmonary oedema. These signs and symptoms can develop within a period of 10 min. Thus the necessity of an efficient first aid method (see below) (Fisher et al. 1980, Hartman and Sutherland 1984, Sutherland 1983, Harrington et al. 1999, Miller et al 2000).
Case fatality rate
If an extremity is affected, a compression bandage is applied and the extremity is immobilised (Sutherland and Duncan 1980, compression-immobilisation method).
Only 1/5 patients had appropriate first aid measures applied prior to the ambulance arrival. Early removal of compression bandage resulted in rapid clinical deterioration in 3/5 patients (Miller et al 2000).
1. Respiratory insufficiency, pulmonary oedema: oxygen; endotracheal intubation and artificial respiration (PEEP). Caution is required if using diuretics to treat the pulmonary oedema if there is concurrent hypovolaemia (Fisher et al. 1980, Sutherland 1983).
2. Hypovolaemia: careful treatment if there is concurrent pulmonary oedema. The pulmonary oedema is probably non-cardiogenic and attributable to increased pulmonary capillary permeability (Fisher et al. 1980, Sutherland 1983).
Funnel-web spider antivenom (CSL, Parkville, Australia).
Systemic envenoming (Sutherland 1983):
- muscle fasciculations in the region of the affected extremity or distant from the site of the bite, then usually initially the lips and tongue,
- hypersalivation and hyperlacrimation,
- arterial hypertension (in the late stage of envenoming arterial hypotension),
- disorientation, impaired consciousness.
Hartman and Sutherland 1984: 9 Atrax sp. bites in patients between 3 and 82 years (identification: A. robustus 6/9, A. formidabilis 2/9, A. bermagui 1/9). Open, uncontrolled, prospective study for evaluation of the efficacy of Funnel-web spider antivenom and adverse reactions to it. Antivenom dose according to the study protocol: 2 vials as the minimum initial dose in cases of mild envenoming. Repetition of this dose if there is no improvement 15 min after the initial dose. Twice this dose in cases of severe envenoming; antivenom is administered i.v. Premedication with an antihistamine with as low a sedative effect as possible and 100 mg of hydrocortisone sodium succinate.
Study results: in all 9 patients there was improvement of the signs and symptoms of envenoming within a period of hours. The patients were able to leave hospital after between 1 and 3 days. The authors argue that without antivenom administration in this group of patients fatalities would have been expected, as well as a hospitalisation period of 2–3 weeks. No adverse reactions were observed that could be conclusively attributed to the antivenom treatment.
Dieckmann et al. 1989: 3 Hadronyche sp. bites (identification: H. versuta 1/3, H. infensa 1/3, H. cerberea 1/3). In all 3 patients there was obvious improvement of the signs and symptoms of envenoming coinciding with the administration of antivenom. The authors note the necessity of repeated administration of antivenom.
Sutherland 1992: 3 Funnel-web spider bites (identification: A. robustus 1/3, H. cerberea 1/3, Atrax sp. 1/3). In all 3 patients there was obvious improvement of the signs and symptoms of envenoming coinciding with the administration of antivenom. The authors note the necessity of repeated administration of antivenom.
Miller et al. 2000: 5 cases of Hadronyche sp. bites. Identification: morphological (male H. cerberea 2/5, male H. formidabilis 1/5), male H. infensa 1/5, male Hadronyche sp. 1/5). Systemic signs of envenoming, in particular early pulmonary oedema, respond rapidly to antivenom. Antivenom requirements may be greater than for Atrax sp. envenoming.
Assessment of the value of antivenom in the treatment of Atrax sp. and Hadronyche sp. envenoming
Antivenom has decidedly transformed the treatment of Atrax sp. and Hadronyche sp. envenoming. According to the available study and case reports, antivenom dramatically reduces case fatality and mortality. The rate of adverse reactions appears to be very low.
Recommendations for first aid and treatment
It is imperative to apply pressure-immobilization as early as possible, ideally within 10 minutes after the bite. The bandage must remain in place until the envenomation syndrome has completely resolved. The first aid knowledge of the population is dangerously deficient (Miller et al 2000). Administration of antivenom in cases of systemic envenoming (for criteria, see above). It is important that antivenom doses are repeated until the desired clinical effect is achieved. Monitoring and treatment of complicated cases of envenoming in an intensive care unit (Dieckmann et al. 1989, Sutherland 1992, Miller et al. 2000).