A large-scale clinical trials was conducted, according to World Health Organization Good Clinical Practice guidelines, in 7 centres in north Cameroon to determine the safety and efficacy of a polyvalent antivenom composed of purified F(ab')2. This study included 223 patients presenting clinically with obvious snake bite, predominantly due to Echis ocellatus (viper), the most abundant species in this savannah region. Clinical surveillance was maintained for 5 d in all patients and until the twenty-sixth day in 74% of cases. Two 10 mL ampoules of polyvalent F(ab')2 equine antivenom (Ipser Africa) were administered to each patient by intravenous infusion. If necessary, treatment was repeated 1 h after the end of the first infusion, and then with a frequency determined by the patient's clinical condition. Before initiation of antivenom treatment, the main clinical disorders observed on admission were oedema (93.7%) and haemorrhage (48.9%), with a clotting time longer than 30 min in 65.4% of patients. Clinical cure was obtained in 213 patients (96.8%). No amputation was necessary, and the case fatality rate was only 1.3%. On average, 4.6 (+/- 3.7) ampoules were administered per patient; 43% of subjects recovered after only a single infusion of 2 ampoules. Early adverse reactions, of varying degrees of severity, were observed in 6.3% of patients. A severe early reaction, anaphylactic shock, was observed in only one patient (0.4%). Serum sickness was observed in another patient. Polyvalent F(ab')2 equine antivenom given by repeated 20 mL intravenous infusions is a safe and effective treatment for envenomation caused by African vipers.
Abstract.A clinical trial was conducted in 2 health centers in northern Cameroon to assess the safety and efficacy of a new polyvalent antivenom composed of highly purified and pasteurized F(abЈ) 2 (FAV-Africa). Forty-six patients with objective signs of envenomation, including 67% with hemorrhage, were included in the study. Each patient received at least 20 ml of FAV-Africa by direct, slow intravenous injection; 172 10-ml ampules were administered. All patients were clinically cured after treatment. Two patients (4.3%) showed minor immediate adverse events that may have been related to FAV-Africa (induration, light-headedness); no other treatment-related adverse event occurred. No patient had serum sickness. This trial confirms the safety of FAV-Africa administered by intravenous injection and its efficacy in the treatment of snake envenomations in sub-Saharan Africa.Antivenom immunotherapy is the only effective treatment against envenomations. In Africa, however, due to the restricted availability of antivenoms, usage constraints, and the fear of adverse reactions, use of serum therapy has been limited. 1 The recent development of antivenoms made of purified fragments of IgG with decreased risk of adverse reactions should improve acceptability of their use under field conditions. FAV-Africa (Pasteur Mérieux Connaught, Lyon, France) is a new highly purified equine F(abЈ) 2 whose manufacturing process involves several additional purification steps compared with those classically used to produce other antivenoms. The venoms involved in the production of FAVAfrica are the same as those used in IPSER-Africa (Pasteur Mérieux Connaught), which include that from Echis leucogaster but not E. ocellatus. 2 It is administered by direct, intravenous injection that results in a rapid distribution of antibodies, and also reduces the material and materials necessary for injection.In this study, which was conducted from January to June 1996 in 2 health centers in northern Cameroon (Garoua Hospital and Doukoula Dispensary), we assessed the safety and efficacy of FAV-Africa in the treatment of snake envenomation. The protocol was approved by the National Ethic Committee of Cameroon prior to initiation of the study.Sixty-one patients reporting to the 2 centers for suspected snake bite underwent a clinical examination, as described by Chippaux and others. 2 Briefly, the clinical examination was standardized for edema and bleeding, and the whole blood clotting time (WBCT) was measured according to the method described by Warrell and others, 3 as modified by Chippaux and others. 2 Forty-six patients (22 at Garoua and 24 at Doukoula) with objective signs of envenomation (i.e., edema, and/or bleeding and/or a WBCT Ն 30 min) were included in the study after providing written informed consent. Snakes were brought in by the victim in 31 cases. Echis ocellatus, a Viperidae that can induce severe hemorrhage, was incriminated 27 times and represented 87% of identified snakes, which is similar to results obtained in a previous survey.2 The ...
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