RESUMO
Context: Although rare, coral snake envenomation is a serious health threat in Brazil, because of the highly neurotoxic venom and the scarcely available antivenom. The major bottleneck for antivenom production is the low availability of venom. Furthermore, the available serum is not effective against all coral snake species found in Brazil. An alternative to circumvent the lack of venom for serum production and the restricted protection of the actually available antivenom would be of great value. We compared the Brazilian coral snake and mono and polyvalent Australian antivenoms in terms of reactivity and protection. Methods: The immunoreactivity of venoms from 9 coral snakes species were assayed by ELISA and western blot using the Brazilian Micrurus and the Australian pentavalent as well as monovalent antiNotechis, Oxyuranus and Pseudechis antivenoms. Neutralization assays were performed in mice, using 3 LD50 of the venoms, incubated for 30 minutes with 100 mu L of antivenom/animal. Discussion: All the venoms reacted against the autologous and heterologous antivenoms. Nevertheless, the neutralization assays showed that the coral snake antivenom was only effective against M. corallinus, M. frontalis, M. fulvius, M. nigrocinctus and M. pyrrhocryptus venoms. On the other hand, the Australian pentavalent antivenom neutralized all venoms except the one from M. spixii. A combination of anti-Oxyuranus and Pseudechis monovalent sera, extended the protection to M. altirostris and, partially, to M. ibiboboca. By adding Notechis antivenom to this mixture, we obtained full protection against M. ibiboboca and partial neutralization against M. lemniscatus venoms. Conclusions: Our findings confirm the limited effectiveness of the Brazilian coral snake antivenom and indicate that antivenoms made from Australian snakes venoms are an effective alternative for coral snake bites in South America and also in the United States were coral snake antivenom production has been discontinued.
RESUMO
Envenomation by coral snakes (Micrurus sp.) is one of the most dangerous injuries in America and it is considered as a serious medical emergency, however bites by these snakes appear to be rare. We analyzed epidemiological data, clinical signs and antivenom use in Argentina during the period between 1979-2003. During this period of study 46 non-fatal Micrurus bites were reported. The majority of cases were men from 31 to 40 years old. Bites occurred primarily in spring and summer. Most cases were reported from the northeast and northwest provinces of the country. The bites were mostly located on hands or feet and occurred mostly during agricultural activities and so mainly involved farmers. Only four cases occurred as a result of handling snakes. The median time it took for antivenom to be administrated was 60 minutes after the bite, and the median number of vials applied was 2. Local pain was mentioned and edema was reported in 41% of patients. All patients recovered without sequelae. This study showed a low incidence of Micrurus bites and low severity of envenomation. However, although no deaths have been reported during the last 30 years, given the toxicity of the venom of Micrurus snakes, the risk of severe envenomation should be considered.
O envenenamento por corais (Micrurus sp.) é um dos mais perigosos na América e considerado uma emergência médica grave ainda que acidentes por estas serpentes pareçam raros. Analisamos dados epidemiológicos e clínicos e o uso de soro antiofídico, durante o período de 1979-2003. As comunicações indicam 46 acidentes por Micrurus, aproximadamente dois casos anuais, sem registro. A maioria dos casos ocorreu em homens de idade entre 31 e 40 anos, principalmente no período de primavera e verão e provenientes do noroeste e nordeste do país. Os acidentes na sua maioria ocorreram em mãos e pés, durante atividades agrícolas envolvendo trabalhadores rurais. Apenas quatro acidentes foram relacionados a manejo dos animais. Em todos os casos analisados houve descrição de dor local e em 41% dos pacientes houve edema. Por paciente foram administradas, em média, duas ampolas. O tempo médio de aplicação do soro foi de 60 minutos. Em todos os casos a recuperação foi favorável sem presença de sequelas. Neste estudo foi possível observar uma baixa incidência de acidentes e baixa severidade nos envenenamentos. Apesar de que não aconteceram mortes nos últimos 30 anos, dado a toxicidade do veneno das cobras corais, o risco de envenenamento severo deveria ser considerado.
