Venoms, antivenoms and immunotherapy

Bee venom phospholipase A2 induces a primary type 2 response that is dependent on the receptor ST2 and confers protective immunity.

The concept of antivenoms was first developed by Henry Sewall in 1887 when he demonstrated that pigeons could be immunized against the effects of pygmy rattlesnake venom by successive inoculations of increasing doses of venom (1). In 1894, Phisalix and Bertrand first used heat-treated venom for immunization, and a year later Albert Calmette showed that serum from inoculated rabbits could protect against the effects of venom when infused into healthy rabbits before venom challenge. In the same year, Calmette used serum from an immunized horse to treat human envenomation following a cobra bite (2), and this was followed by the production of the first specific immune serum against cobra venom by Fraser. The first commercial equine antivenoms were produced by Calmette in 1898 for use in Vietnam, and in 1911, Vital Brazil first carried out large-scale antivenom production in Brazil. Antivenom was subsequently produced in a number of different countries including the United States, Australia, Brazil, and Japan (3,4).

Snake Antivenoms: Antivenoms

Scorpion stings are common in many tropical countries. Although most scorpion stings cause only localized pain without life-threatening envenoming, about one third of stings cause systemic envenoming which can result in death. Children are particularly sensitive to scorpion envenoming. The severity of scorpion stings is related to the presence of neurotoxins in the venom that cause a sudden release of neurotransmitters from the autonomic nervous system, predominantly sympathetic. There is also a strong inflammatory response that worsens symptoms, including those of a respiratory nature. Several vital functions may be directly affected, including the cardiovascular, respiratory, and neuromuscular systems. Hypertension is constant at the beginning of systemic envenoming and sometimes has a severe cardiac and respiratory impact. Although controversial, immunotherapy is the only etiological treatment. Administered early, it prevents many complications and improves the outcome. New antivenoms are highly purified immunoglobulin fragments, the efficacy and safety of which are excellent. As a consequence, adverse reactions to antivenoms are now very rare and usually mild, which should limit any reluctance regarding their routine use. Symptomatic treatment is still necessary to support immunotherapy, especially in cases of delayed arrival at hospital. A combination of both approaches should be considered, based on local resources and constraints.

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Emerging options for the management of scorpion stings

ISBN 2-7099-1599-5 ISSN 1286-4994 Les serpents d’Afrique occidentale et centrale met à la disposition du naturaliste, professionnel comme amateur, l’information la plus complète, à partir des études les plus récentes, sur les serpents rencontrés de la Mauritanie jusqu’au Tchad et au Congo. La première partie est consacrée aux généralités : caractéristiques, origines et évolution des ophidiens, composition des venins, épidémiologie des morsures, symptomatologie des envenimations et traitement. La seconde traite de la systématique des serpents de la région couverte : de nombreuses clés dichotomiques permettent l’identification du serpent, même par un non-spécialiste ; une carte de répartition, un dessin de la tête – et parfois du maxillaire ou de l’hémipénis – complètent la description de chaque taxon ; des notes de biologie et d’écologie sont rassemblées à la fin de chacune des notices d’identification. Une soixantaine de photographies de morsures et des principales espèces rencontrées illustrent cet ouvrage. Un index comportant les noms anciens et actuels de toutes les espèces facilite l’accès aux descriptions. Enfin, la bibliographie est riche de près de 800 références.

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Les serpents d'Afrique occidentale et centrale

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La sérothérapie antivenimeuse : ses applications, ses limites, son avenir

Although the main Malian scorpion species of medical interest, Androctonus amoreuxi, is responsible for severe envenomings and perhaps some deaths, it has hitherto been considered not dangerous for humans. This population is located in the Saharian North-Eastern regions of Mali where it is accompanied by Leiurus quinquestriatus, a well known dangerous species of the Sahara. In the Gao district, divided by the Niger River, less desolate than the Tessalit and Kidal regions, one specimen of the dangerous species Androctonus australis was found. To summarize, Mali harbors at least three dangerous scorpion species: Leiurus quinquestriatus, Androctonus amoreuxi and A. australis, the latter recently having been identified in Mali for the first time. The absence of Androctonus aeneas is surprising in this context because it is found in neighboring countries (Algeria, Niger) and should be detected by new surveys. The possibility of preparing a single scorpion antivenom intended for Saharian and sub-Saharian populations is discussed.

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Dangerous scorpion fauna of Mali

The risk of being bitten by a snake or stung by a scorpion is low for the ordinary, non-thrill-seeking traveler. Travelers who plan hazardous outdoor activities should be advised to be careful and bring along adequate protective clothing (boots, long trousers, and gloves). If envenomation occurs, the victim should be immobilized and rushed to a treatment center. Administration of antivenin using massive doses in severe cases is the best therapy. For quickest and most efficient results, antivenins should be administered by the intravenous route. Packing antivenins is necessary only under special circumstances when high-risk activities are scheduled. In this case contingency planning may also be necessary taking into account health care facilities in the destination country and the availability of antivenins.

M. Goyffon

Papers

Venoms, antivenoms and immunotherapy

La sérothérapie antivenimeuse : ses applications, ses limites, son avenir

Dangerous scorpion fauna of Mali

[Snakes and scorpions: what are the risks for the traveler?].

La découverte du sérum antivenimeux [10 février 1894]