Studies

Androctonus australis (Androctonus aeneas)
Tunisia

Goyffon et al. 1982: 27 patients hospitalised with scorpion stings from a total of 717 accidents. Identification: in the cases where the patient brought the scorpion to the hospital, A. australis was the chief cause of severe envenoming, and sometimes A. aeneas. It is not possible to attribute the clinical descriptions presented to clearly identified scorpion species.

The symptoms of systemic envenoming described roughly correspond to those caused by Leiurus quinquestriatus.

 

Androctonus australis and Buthus occitanus

Tunisia

Abroug et al 1999: 825 patients with scorpion stings. Identification: positive history of scorpion sting, with the scorpion being seen or captured with A. australis and B. occitanus being the two most common species in the area.

 

Androctonus mauretanicus mauretanicus and Buthus occitanus 

Morocco

Ghalim et al. 2000: 275 patients with scorpion stings. Identification: by the patient or the physician. Prevalent in the area: Buthus occitanus and Androctonus mauretanicus mauretanicus; venom serum levels were quantified using an ELISA. Severity scale (Krifi et al. 1998) : Grade I (only local symptoms, local pain and a burning sensation) (247/275); grade II (local and systemic symptoms) (28/275); grade III (local and systemic symptoms with cardiovascular shock, respiratory failure, acute pulmoary oedema, priapism, convulsions) (0/275).

 

Signs & symptoms

Autopharmacological effects

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 scorpion venom. As these are transmitters in the sympathetic, parasympathetic and somatic nervous systems, the resulting clinical symptoms of envenoming are dealt with in the section "Neurological effects".

However, scorpion venoms are also believed to lead to other indirect effects that are caused by the release of autopharmacologically active substances (such as kinins, prostaglandins and slow-reacting substances). The pathophysiological effects of these substances overlap to a great extent. This makes it difficult to be certain about aetiology. In particular with regard to pulmonary oedema, there has been discussion concerning the effects of mediators on vascular permeability, which might constitute a non-cardiac component of the pulmonary oedema. Peripheral blood pressure regulation is also responsive to a variety of different mediators that might be released.

Local effects

Androctonus australis and Buthus occitanus

Tunisia

Isolated local pain 680/825, local pain associated with other symptoms 145/825 (Abroug et al 1999).

 

Androctonus mauretanicus mauretanicus and Buthus occitanus 

Morocco

Local pain 185/217, burning sensation 93/192 (Ghalim et al. 2000).

Neurological effects (autonomic and somatic nervous system)

Androctonus australis and Buthus occitanus

Tunisia

Hypertension 94/825, shivering 11/825, vomiting 17/825, priapism 16/825, cardiogenic shock 9/825, pulmonary oedema 6/825, altered consciousness 2/825 (Abroug et al 1999).

 

Androctonus mauretanicus mauretanicus and Buthus occitanus 

Morocco

Sweating 30/256, shivering 11/258 (Ghalim et al. 2000).

Case fatality rate

Androctonus australis and Buthus occitanus

Tunisia

2/825 (refractory shock) (Abroug et al 1999).

Treatment (specific)

Androctonus australis and Buthus occitanus

Tunisia

Patients developing life-threatening complcations: ICU. 8/825 required mechanical ventilation (5 in the antivenom group, 3 in the placebo group) (Abroug et al 1999).

Treatment (specific)

Androctonus australis and Buthus occitanus

Tunisia

Abroug et al 1999: Prospective randomized controlled trial in Tunesia to assess the routine administration of 20 ml bivalent (A. australis, B. occitanus) F(ab')₂ scorpion antivenom (Institut Pasteur, Tunis, Tunesia), i.v., versus placebo irrespective of clinical severity. N=825 (, patients >10 years. Grading of severity: absence (grade I) or presence (grade II) of systemic envenoming. Diagnosis of scorpion envenoming based on a positive history of scorpion sting, with the scorpion being seen or captured. A. australis and B. occitanus are the two most common species in the area.

Results: cure rates (55% scorpion antivenom, 66% placebo) and preventive effect for moving into a higher severity grade (94% scorpion antivenom, 96% placebo) were similar.

Conclusions: No benefit was found in routine administration of scorpion antivenom after scorpion sting, irrespective of clinical severity.

 

Androctonus mauretanicus mauretanicus and Buthus occitanus 

Morocco

Ghalim et al. 2000: Prospective study of patients with scorpion stings. N=275. Identification: by the patient or the physician. Prevalent in the area: Buthus occitanus and Androctonus mauretanicus mauretanicus. Venom serum levels were quantified using an ELISA. Severity scale (Krifi et al. 1998) : Grade I (only local symptoms, local pain and a burning sensation) (247/275); grade II (local and systemic symptoms) (28/275); grade III (local and systemic symptoms with cardiovascular shock, respiratory failure, acute pulmoary oedema, priapism, convulsions) (0/275).179/275 were treated with equine F(ab')₂ scorpion antivenom (Androctonus mauretanicus mauretanicus) (27% 2-5 ml; 73% 10ml). Antivenom application 77.6% i.m., 6.2% s.c., 16.2% both.

Results: Venom serum levels were higher in grade II than in grade I patients. Significant decrease in venom serum levels and clinical improvement was observed after 10 ml antivenom and not so in patients receiving 2-5 ml of antivenom. Over the same time period no difference in venom serum levels in patients not treated with antivenom.

Conclusions:  Antivenom is effective in decreasing circulating venom serum levels and morbidity. It is more efficient, however, when given as soon as possible after envenoming and in adequate doses:

(note: antivenom has been administered in this study i.m. /s.c. and not i.v.)