Efficacy of serum therapy on the treatment of rats experimentally envenomed by bristle extract of the caterpillar Lonomia obliqua: comparison with epsilon-aminocaproic acid therapy.

Large number of accidents caused by contact with Lonomia obliqua caterpillars, with hemorrhagic complications, have occurred in southern Brazil. Based on Venezuelan expertise to treat Lonomia achelous envenomation, the use of the antifibrinolytic drug epsilon-aminocaproic acid (EACA) has been indicated to treat L. obliqua envenomation, although no evidence has been presented to justify its use. Specific antivenom (antilonomic serum (ALS)) that neutralizes toxins that cause envenomation was developed. To compare the effectiveness of such treatments, rats were injected i.d. with the bristle extract of L. obliqua caterpillars and treated 15 min, 1 and 6 h after with saline, ALS, EACA, or with both ALS and EACA. ALS elicited fibrinogen recovery and normalization of thrombin time (TT), prothrombin time (PT) and activated partial thromboplastin time (APTT), independent of when it was administered; however, hematocrit was decreased in the group treated later. Saline or EACA-treated groups presented neither fibrinogen recovery nor normalization of hemostatic parameters. A high death rate was observed in the group treated with EACA 15 min after the envenomation. Prolongation of TT and APTT observed in the group treated with EACA and ALS indicated that this association gave no benefit in relation to the group treated solely with ALS. The results presented herein suggest that ALS is the only effective treatment for envenomation caused by contact with Lonomia obliqua caterpillars and indicate that EACA should not be administered in the initial phase of envenomation.

Short report: A case of hemolysis resulting from contact with a Lonomia caterpillar in southern Brazil.

Contact with a caterpillar of the genus Lonomia can result in a hemorrhagic syndrome. Lonomia obliqua venom activates prothrombin and factor X and promotes fibrinogenolytic activity. Although crude L. obliqua bristle extract can induce hemolytic activity in human and rat erythrocytes, there have been no reports of hemolysis in the cases of human contact. We report a confirmed human case of Lonomia venom-induced hemolysis.

The effect of experimental Bothrops jararaca envenomation on pregnant mice.

The injury caused by the intramuscular injection of a single dose of Bothrops jararaca venom (0.24 mg/kg body weight) to mice on day 8 of pregnancy and examined on day 9 was investigated. Macroscopic and histological examination showed that the bothropic venom caused an increase in the incidence of fetal resorptions. Histologically, a characteristic involution of mature decidua was noticed in saline-treated mice; however, necrotic trophoblast giant cells and decidual cells were also present in this region of mice treated with B. jararaca venom, mainly close to the embryo. Hemorrhagic areas were also observed at maternal-fetal interface, which contained maternal erythrocytes and polymorphonuclears. Plasma fibrinogen levels were lower in envenomed group (p < or = 0.0001), but prothrombin time and activated partial thromboplastin time remained unaltered. Total and differential white blood cell counts were not statistically different between groups. Thus, B. jararaca venom causes injuries not only to the fetus, but also to decidual tissue and blood coagulation of pregnant mice. It is not clear, nonetheless, whether disturbances during the development of pregnancy are due to a direct effect of venom on uterus/fetus or to homeostatic changes in dams, such as clotting disturbances, or to both of them.

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

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.

Clinical trial of two antivenoms for the treatmentof Bothrops and Lachesis bites in the northeastern Amazon region of Brazil

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.