Clinical trial of two antivenoms for the treatment of Bothrops and Lachesis bites in the north eastern Amazon region of Brazil

Abstract

The efficacies of specific Bothrops atrox-Lachesis and standard Bothrops-Lachesis antivenoms were compared in the north eastern Amazon region of Brazil. The main aim was to investigate whether a specific antivenom raised against the venom of B. atrox, the most important Amazon snake species from a medical point of view, was necessary for the treatment of patients in this region. Seventy-four patients with local and systemic effects of envenoming by Bothrops or Lachesis snakes were randomly allocated to receive either specific (n = 38) or standard (n = 36) antivenoms. In 46 cases (24 in the standard antivenom group, 22 in the other) the snake was identified either by enzyme immunoassay or by examination of the dead snake, as B. atrox in 45, L. muta in one. Patients were similar in all clinical and epidemiological respects before treatment. Results indicated that both antivenoms were equally effective in reversing all signs of envenoming detected both clinically and in the laboratory. Venom-induced haemostatic abnormalities were resolved within 24 h after the start of antivenom therapy in most patients. The extent of local complications, such as local skin necrosis and secondary infection, was similar in both groups. There were no deaths. The incidence of early anaphylactic reactions was 18% and 19%, respectively for specific and standard antivenoms; none was life-threatening. Measurement of serum venom concentrations by enzyme immunoassay (EIA) confirmed that both antivenoms cleared venom antigenaemia effectively. EIA also revealed that one patient had been bitten by Lachesis muta, although the clinical features in this case were not distinctive.

Crotaline snake bite in the Ecuadorian Amazon: randomised double blind comparative trial of three South American polyspecific antivenoms

“…B atrox is notorious as the leading cause of severe snake bites wherever it occurs in South America 4 16. In contrast, B bilineatus , a distinctive bright green arboreal snake, is less well known as a snake of real medical importance 30.…”

Comparison of venoms from wild and long-term captive Bothrops atrox snakes and characterization of Batroxrhagin, the predominant class PIII metalloproteinase from the venom of this species

“…The abundance of PIII-SVMPs in B. atrox venom is strongly correlated with the symptoms of human envenomings by this species [21]. Venom metalloproteinases, particularly PIII-SVMPs, are responsible for the local and systemic hemorrhage and are also involved in the local lesions due to their pro-inflammatory action or the ischemia at the site of the bite which arises from the reduction of blood supply following the damage of microvasculature [22,23].…”

Systemic antivenom and skin necrosis after green pit viper bites

“…The effectiveness of antivenom in treating local toxicity due to viper venoms was equivocal in several clinical trials evaluating systemic effects (7)(8)(9)(10). A retrospective study found that antivenom administration was associated with less severe edema after Vipera Berus envenomation (11).…”