Neurotoxical activity of Micrurus snake venom and methods for its analysis. A literature review / Actividad neurotóxica del veneno de serpientes del género Micrurus y métodos para su análisis. Revisión de la literatura

Abstract Introduction: Snakes of the genus Micrurus have fossorial habits, passive temperament and scarce production of powerful venom with neurotoxic characteristics that block the synaptic transmission at the neuromuscular junction. Objective: To present an overview of the neurotoxicity of the Micrurus snake venom, and its functional characterization by ex vivo analysis methods. Materials and methods: A literature review was conducted in MedLine and ScienceDirect using specific terms and their combinations. Search strategy: type of studies: articles on the neurotoxicity of Micrurus snake venom and techniques to determine its neurotoxic activity by in vitro, in vivo and ex vivo models; publication period: articles published until June 2018; publication language: English and Spanish. Results: Out of 88 studies identified in the initial search, 28 were excluded because they did not meet the inclusion criteria (based on reading their titles and abstracts). 8 additional articles (books and reports) were included, since, according to the authors' opinion, they complemented the information reported by the selected studies. The studies included in the review (n=68) were original research papers (n=44), review articles (n = 16), and book chapters, reports, guides and online consultations (n=8). Conclusions: Studies performed using ex vivo muscle and nerve preparations to evaluate the effect of neurotoxins provide a good model for the characterization of the pre-synaptic and post-synaptic effect of the venom produced by snakes of the genus Micrurus.

Resumen Introducción. Las serpientes del género Micrurus son animales de hábitos fosoriales, de temperamento pasivo y escasa producción de un potente veneno con características neurotóxicas que bloquean la transmisión sináptica en la placa neuromuscular. Objetivo. Presentar un panorama general de la neurotoxicidad del veneno de las serpientes Micrurus y su caracterización funcional mediante métodos de análisis ex vivo. Materiales y métodos. Se realizó una revisión de la literatura en MedLine y ScienceDirect usando términos específicos y sus combinaciones. Estrategia de búsqueda: tipo de estudios: artículos sobre la neurotoxicidad del veneno de serpientes Micrurus y técnicas para determinar su actividad neurotóxica mediante modelos in vitro, in vivo y ex vivo; periodo de publicación: sin límite inicial a junio de 2018; idiomas: inglés y español. Resultados. De los 88 estudios identificados en la búsqueda inicial, se excluyeron 28 por no cumplir los criterios de inclusión (basándose en la lectura de títulos y resúmenes); además, se incluyeron 8 documentos adicionales (libros e informes), que, a criterio de los autores, complementaban la información reportada por las referencias seleccionadas. Los estudios incluidos en la revisión (n=68) correspondieron a las siguientes tipologías: investigaciones originales (n=44), artículos de revisión (n=16) y capítulos de libros, informes, guías y consultas en internet (n=8). Conclusiones. Los estudios que describen el uso de preparaciones ex vivo de músculo y nervio para evaluar el efecto de neurotoxinas ofrecen un buen modelo para la caracterización del efecto presináptico y postsináptico del veneno producido por las serpientes Micrurus.

Effects of Mlx-8, a phospholipase A2 from Brazilian coralsnake Micrurus lemniscatus venom, on muscarinic acetylcholine receptors in rat hippocampus

Here, we described the presence of a neurotoxin with phospholipase A2 activity isolated from Micrurus lemniscatus venom (Mlx-8) with affinity for muscarinic acetylcholine receptors (mAChRs). Methods: The purification, molecular mass determination, partial amino acid sequencing, phospholipase A2 activity determination, inhibition of the binding of the selective muscarinic ligand [3H]QNB and inhibition of the total [3H]inositol phosphate accumulation in rat hippocampus of the Mlx-8 were determined. Results: Thirty-one fractions were collected from HPLC chromatography, and the Mlx-8 toxin was used in this work. The molecular mass of Mlx-8 is 13.628 Da. Edman degradation yielded the following sequence: NLYQFKNMIQCTNTRSWL-DFADYG-CYCGRGGSGT. The Mlx-8 had phospholipase A2 enzymatic activity. The pKi values were determined for Mlx-8 toxin and the M1 selective muscarinic antagonist pirenzepine in hippocampus membranes via [3H]QNB competition binding assays. The pKi values obtained from the analysis of Mlx-8 and pirenzepine displacement curves were 7.32 ± 0.15, n = 4 and 5.84 ± 0.18, n = 4, respectively. These results indicate that Mlx-8 has affinity for mAChRs. There was no effect on the inhibition ability of the [3H]QNB binding in hippocampus membranes when 1 µM Mlx-8 was incubated with 200 µM DEDA, an inhibitor of phospholipase A2. This suggests that the inhibition of the phospholipase A2 activity of the venom did not alter its ability to bind to displace [3H]QNB binding. In addition, the Mlx-8 toxin caused a blockade of 43.31 ± 8.86%, n = 3 and 97.42 ± 2.02%, n = 3 for 0.1 and 1 µM Mlx-8, respectively, on the total [3H]inositol phosphate content induced by 10 µM carbachol. This suggests that Mlx-8 inhibits the intracellular signaling pathway linked to activation of mAChRs in hippocampus. Conclusion: The results of the present work show, for the first time, that muscarinic receptors are also affected by the Mlx-8 toxin, a muscarinic ligand with phospholipase A2 characteristics, obtained from the venom of the Elapidae snake Micrurus lemniscatus, since this toxin was able to compete with muscarinic ligand [3H]QNB in hippocampus of rats. In addition, Mlx-8 also blocked the accumulation of total [3H]inositol phosphate induced by muscarinic agonist carbachol. Thus, Mlx-8 may be a new pharmacological tool for examining muscarinic cholinergic function.(AU)

True or false coral snake: is it worth the risk? A Micrurus corallinus case report

Bites provoked by the genus Micrurus represent less than 1% of snakebite cases notified in Brazil, a tiny fraction compared with other genus such as Bothrops and Crotalus, which together represent almost 80% of accidents. In addition to their less aggressive behavior, habits and morphology of coral snakes are determinant factors for such low incidence of accidents. Although Micrurus bites are rare, victims must be rescued and hospitalized in a short period of time, because this type of envenoming may evolve to a progressive muscle weakness and acute respiratory failure. Case Presentation We report an accident caused by Micrurus corallinus involving a 28-year-old Caucasian sailor man bitten on the hand. The accident occurred in a recreational camp because people believed the snake was not venomous. The victim presented neurological symptoms 2 h after the accident and was taken to the hospital, where he received antielapidic serum 10 h after the bite. After the antivenom treatment, the patient presented clinical evolution without complications and was discharged 4 days later. Conclusions: We reinforce that it is essential to have a health care structure suitable for the treatment of snakebite. Besides, the manipulation of these animals should only be carried out by a team of well-equipped and trained professionals, and even so with special attention.(AU)

True or false coral snake: is it worth the risk? A Micrurus corallinus case report

Background Bites provoked by the genus Micrurus represent less than 1% of snakebite cases notified in Brazil, a tiny fraction compared with other genus such as Bothrops and Crotalus, which together represent almost 80% of accidents. In addition to their less aggressive behavior, habits and morphology of coral snakes are determinant factors for such low incidence of accidents. Although Micrurus bites are rare, victims must be rescued and hospitalized in a short period of time, because this type of envenoming may evolve to a progressive muscle weakness and acute respiratory failure. Case Presentation We report an accident caused by Micrurus corallinus involving a 28-year-old Caucasian sailor man bitten on the hand. The accident occurred in a recreational camp because people believed the snake was not venomous. The victim presented neurological symptoms 2 h after the accident and was taken to the hospital, where he received antielapidic serum 10 h after the bite. After the antivenom treatment, the patient presented clinical evolution without complications and was discharged 4 days later. Conclusions We reinforce that it is essential to have a health care structure suitable for the treatment of snakebite. Besides, the manipulation of these animals should only be carried out by a team of well-equipped and trained professionals, and even so with special attention.

Biological and molecular properties of yellow venom of the Amazonian coral snake Micrurus surinamensis

Abstract INTRODUCTION: The coral snake Micrurus surinamensis, which is widely distributed throughout Amazonia, has a neurotoxic venom. It is important to characterize the biological and molecular properties of this venom in order to develop effective antitoxins. METHODS: Toxins from the venom of M. surinamensis were analyzed by two-dimensional polyacrylamide gel electrophoresis and their neurotoxic effects in vivo were evaluated. RESULTS AND CONCLUSIONS: Most proteins in the venom had masses < 14kDa, low phospholipase A2 activity, and no proteolytic activity. The toxins inhibited the coagulation cascade. The venom had neurotoxic effects in mice, with a median lethal dose upon intravenous administration of 700 µg/kg. Immunogenic studies revealed abundant cross-reactivity of antielapidic serum with 14kDa toxins and limited cross-reactivity with toxins < 10kDa. These results indicate that antielapidic serum against M. surinamensis venom has weak potency (0.35mg/ml) in mice.

Envenomation by the red-tailed coral snake (Micrurus mipartitus) in Colombia

Background Although the red-tailed coral snake (Micrurus mipartitus) is widely distributed in Colombia and its venom is highly neurotoxic and life threatening, envenomation by this species is rare. Therefore, this report may shed some light on the clinical presentation of M. mipartitus bites. Case presentations Herein, we describe two cases of patients bitten by red-tailed coral snakes, illustrating the clinical presentation of the victims, the outcomes and treatment provided. Conclusion Envenomation caused by M. mipartitus provokes predicable neurotoxicity, and its treatment should be based on respiratory support and use of specific antivenom.(AU)

Envenomation by the red-tailed coral snake (Micrurus mipartitus) in Colombia

Abstract Background Although the red-tailed coral snake (Micrurus mipartitus) is widely distributed in Colombia and its venom is highly neurotoxic and life threatening, envenomation by this species is rare. Therefore, this report may shed some light on the clinical presentation of M. mipartitus bites. Case presentations Herein, we describe two cases of patients bitten by red-tailed coral snakes, illustrating the clinical presentation of the victims, the outcomes and treatment provided. Conclusion Envenomation caused by M. mipartitus provokes predicable neurotoxicity, and its treatment should be based on respiratory support and use of specific antivenom.

Heterologous expression, protein folding and antibody recognition of a neurotoxin from the Mexican coral snake Micrurus laticorallis

Background The cysteine-rich neurotoxins from elapid venoms are primarily responsible for human and animal envenomation; however, their low concentration in the venom may hamper the production of efficient elapid antivenoms. Therefore, the aim of the present study was to produce fully active elapid neurotoxic immunogens for elapid antivenom production. Method Cysteine-rich neurotoxins showed recombinant expression in two strains of E. coli, and were purified using affinity chromatography and reverse-phase HPLC (rpHPLC). Results The cDNA of the four disulfide-bridged peptide neurotoxin Mlat1 was cloned into a modified expression vector, pQE30, which was transfected into two different E. coli strains. The recombinant toxin (HisrMlat1) was found only in inclusion bodies in M15 strain cells, and in both inclusion bodies and cytoplasm in Origami strain cells. The HisrMlat1 from inclusion bodies from M15 cells was solubilized using guanidine hydrochloride, and then purified by rpHPLC. It showed various contiguous fractions having the same molecular mass, indicating that HisrMlat1 was oxidized after cell extraction forming different misfolded disulfide bridge arrangements without biological activity. In vitro folding conditions of the misfolded HisrMlat1 generated a biologically active HisrMlat1. On the other hand, the HisrMlat1 from the cytoplasm from Origami cells was already soluble, and then purified by HPLC. It showed a single fraction with neurotoxic activity; so, no folding steps were needed. The in vitro folded HisrMlat1 from M15 cells and the cytoplasmic soluble HisrMlat1from Origami cells were indistinguishable in their structure and neurotoxicity. Rabbit polyclonal antibodies raised up against biologically active HisrMlat1 recognized the native Mlat1 (nMlat1) from the whole venom of M. laticorallis. In addition, HisrMlat1 was recognized by horse polyclonal antibodies obtained from the immunization of elapid species from sub-Saharan Africa. Conclusion HisrMlat1 shows increased biological activities compared to the native peptide, and may be used as an immunizing agent in combination with other toxic components such phospholipases type A2 for elapid antivenom production.(AU)

Heterologous expression, protein folding and antibody recognition of a neurotoxin from the Mexican coral snake Micrurus laticorallis

The cysteine-rich neurotoxins from elapid venoms are primarily responsible for human and animal envenomation; however, their low concentration in the venom may hamper the production of efficient elapid antivenoms. Therefore, the aim of the present study was to produce fully active elapid neurotoxic immunogens for elapid antivenom production. Method Cysteine-rich neurotoxins showed recombinant expression in two strains of E. coli, and were purified using affinity chromatography and reverse-phase HPLC (rpHPLC). Results The cDNA of the four disulfide-bridged peptide neurotoxin Mlat1 was cloned into a modified expression vector, pQE30, which was transfected into two different E. coli strains. The recombinant toxin (HisrMlat1) was found only in inclusion bodies in M15 strain cells, and in both inclusion bodies and cytoplasm in Origami strain cells. The HisrMlat1 from inclusion bodies from M15 cells was solubilized using guanidine hydrochloride, and then purified by rpHPLC. It showed various contiguous fractions having the same molecular mass, indicating that HisrMlat1 was oxidized after cell extraction forming different misfolded disulfide bridge arrangements without biological activity. In vitro folding conditions of the misfolded HisrMlat1 generated a biologically active HisrMlat1. On the other hand, the HisrMlat1 from the cytoplasm from Origami cells was already soluble, and then purified by HPLC. It showed a single fraction with neurotoxic activity; so, no folding steps were needed. The in vitro folded HisrMlat1 from M15 cells and the cytoplasmic soluble HisrMlat1from Origami cells were indistinguishable in their structure and neurotoxicity. Rabbit polyclonal antibodies raised up against biologically active HisrMlat1 recognized the native Mlat1 (nMlat1) from the whole venom of M. laticorallis. In addition, HisrMlat1 was recognized by horse polyclonal antibodies obtained from the immunization of elapid species from sub-Saharan Africa. Conclusion HisrMlat1 shows increased biological activities compared to the native peptide, and may be used as an immunizing agent in combination with other toxic components such phospholipases type A2 for elapid antivenom production.

Reconhecimento de frações do veneno de cobras corais brasileiras pelo soro antielapídico / Recognition of venom fractions from Brazilian coral snakes by antielapid serum

Objetivos: Investigar a capacidade do soro antielapídico produzido no Brasil na identificação de frações do veneno de seis espécies, incluindo as que constituem o pool de inoculação: Micrurus brasiliensis, M. corallinus, M. frontalis, M. lemniscatus, M. spixii e M. surinamensis. Métodos: As amostras utilizadas fazem parte do banco de venenos do Centro de Estudos e Pesquisas Biológicas, da Pontifícia Universidade Católica de Goiás. O soro antielapídico foi cedido pela Fundação Ezequiel Dias. As metodologias empregadas foram eletroforese e imunoblotting. Resultados: Foi demonstrada uma variabilidade toxinológica e uma capacidade também variável de reconhecimento desses componentes pelo soro antielapídico. A partir da técnica de western-blotting o soro antielapídico da Fundação Ezequiel Dias foi capaz de reconhecer a maioria, mas não todos os componentes presentes nos venenos analisados. Conclusões: Os resultados sugerem uma eficácia restrita do soro antielapídico já que o mesmo possui limitações quanto as espécies Amazônicas, o que reforça a necessidade de uma revisão dos estudos intra e interespecíficos dos venenos micrúricos.

Aims: To investigate whether the antielapid serum produced in Brazil could identify venom fractions from six species of Micrurus, including those in the inoculation pool: Micrurus brasiliensis, M. corallinus, M. frontalis, M. lemniscatus, M. spixii, and M. surinamensis. Methods: The samples belong to the venom bank of the Center for Biological Studies and Research from the Pontifícia Universidade Católica de Goiás, Brazil. The antielapid serum was granted by the Ezequiel Dias Foundation. Both electrophoresis and immunoblotting methods were used. Results: Variability in venom components and in the ability to recognize such components was demonstrated by the antielapid serum. Based on the western-blotting technique, the antielapid serum from Ezequiel Dias Foundation was able to recognize most, but not all the components present in the analyzed venoms. Conclusions: The results suggest restricted efficacy of the antielapid serum, due to its limitations against species from the Amazon region, reinforcing the need for a review of intraspecific and interspecific studies of Micrurus venoms.

CORAL SNAKE ANTIVENOM PRODUCED IN CHICKENS (Gallus domesticus) / Antiveneno de serpiente coral producido en gallinas (Gallus domesticus)

The production of anti-snake venom from large mammal's blood has been found to be low-yielding and arduous, consequently, antivenom immunoglobulins for treatment are achieved regularly as polyvalent serum. We have standardized an undemanding technique for making purified immunoglobulin IgY antivenom consisting of polyclonal antibodies against coral snake venom in the egg yolk of immunized hens. We have adapted a reported process of antibody purification from egg yolks, and achieved 90% antibody purity. The customized technique consisted of the removal of lipids from distilled water-diluted egg yolks by a freeze–thaw sequence. The specific immunoglobulins were present in the egg yolk for up to 180 days postimmunization. Therefore, by means of small venom quantities, a significant amount of immunoglobulins were found in an adequately purified state (The obtained material contained about 90% pure IgY). The antigen binding of the immunoglobulins was detected by a double immunodiffusion test. Titers of antibodies in the yolk were estimated with a serum protection assay (Median effective dose = ED50) (ED50= 477 mg/kg). Given that breeding hens is economically feasible, egg gathering is noninvasive and the purification of IgY antibodies is quick and easy, chicken immunization is an excellent alternative for the production of polyclonal antibodies. To the best of our knowledge, this is the first coral snake antivenom prepared in birds.

La producción de antiveneno de serpiente usando sangre de grandes mamíferos se ha encontrado que es de bajo rendimiento y de trabajo arduo, en consecuencia, las inmunoglobulinas antiveneno para el tratamiento se obtienen generalmente, como suero polivalente. Hemos estandarizado una técnica poco exigente para la fabricación de inmunoglobulina purificada IgY, que consistió en generar anticuerpos policlonales contra el veneno de la serpiente coral en huevos de gallinas inmunizadas. La técnica consistió en la eliminación de lípidos de las yemas del huevo, diluidas en agua y en una secuencia de congelación-descongelación. Las inmunoglobulinas específicas estuvieron presentes en la yema de huevo hasta 180 días después de la inmunización. La unión del antígeno a las inmunoglobulinas se detectó mediante un ensayo de inmunodifusión doble. Los títulos de anticuerpos en la yema fueron estimados con un ensayo de protección (dosis efectiva media = ED50). Dado que las gallinas reproductoras son económicamente viables, la recolección de huevos es no invasiva y la purificación de anticuerpos IgY es rápida y fácil, la inmunización de la gallina es una excelente alternativa para la producción de anticuerpos policlonales. A nuestro entender, esta es el primer anti-veneno contra serpiente de coral preparado en aves.

Envenoming by coral snakes (Micrurus) in Argentina, during the period between 1979-2003 / Envenenamento por cobras corais na Argentina durante o período 1979-2003

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.

Envenomation by Micrurus coral snakes in the Brazilian Amazon region: report of two cases / Envenenamento por coral do gênero Micrurus na Amazônia brasileira: relato de dois casos

Two cases of proven coral snake bites were reported in Belém, Pará State, Brazil. The first case was a severe one caused by Micrurus surinamensis. The patient required mechanical ventilation due to acute respiratory failure. The second case showed just mild signs of envenomation caused by Micrurus filiformis. Both patients received specific Micrurus antivenom and were discharged without further complications. Coral snake bites are scarcely reported in the Amazon region and there is a broad spectrum of clinical manifestations, varying from extremely mild to those which may rapidly lead to death if the patient is not treated as soon as possible.

Dois acidentes por coral verdadeira são descritos em Belém, Pará. O primeiro caso foi decorrente de envenenamento por Micrurus surinamensis, no qual a vítima necessitou ventilação mecânica por insuficiência respiratória. O segundo, causado por Micrurus filiformis, apresentou apenas manifestações leves. Ambos os pacientes receberam soro antielapídico específico e evoluíram sem complicações. Acidentes por coral verdadeira na região Amazônica são raramente descritos e podem cursar com um largo espectro de alterações, que variam desde quadros de envenenamento muito leves até manifestações com risco de óbito.

New reports on parasitism by Haplometroides buccicola (Digenea, Plagiorchiidae) in Brazilian snakes

The occurrence of Haplometroides buccicola (Digenea, Plagiorchiidae) in the esophagus of two Brazilian snakes is reported in the present study. The trematodes were collected from one Micrurus corallinus (Elapidae) and one Phalotris lativittatus (Colubridae); both snakes were found in Botucatu city, São Paulo State, Brazil. Morphological and morphometric analyses of the trematodes are presented. For the first time Micrurus corallinus has been recorded as a host for H. buccicola and this is the second time that P. lativittatus has been reported as a host for this trematode species.

Estudo cariotípico de duas espécies brasileiras do gênero Micrurus (Ophidia: Elapidae) / Karyotypic studies of two Brazilian species of the genus Micrurus (Ophidia: Elapidae)

Descrevemos neste trabalho o cariótipo de duas espécies de cobra coral (Ophidia: Elapidae) do Brasil: Micrurus corallinus e M. ibiboboca. Preparações citológicas foram obtidas através da técnica de esmagamento, seguida de coloração convencional com Giemsa. Encontramos para M. corallinus, um número diplóide (2n) de 40 cromossomos, com fórmula cariotípica 40 (4; 16; 20) e constricção secundária no segundo par de macrocromossomos subtelocêntricos. Micrurus ibiboboca apresentou 2n = 42, com fórmula cariotípica 42 (2; 20; 20) e constricção secundária no primeiro par de macrocromossomos telocêntricos. As primeiras descrições dos cariótipos das espécies M. corallinus e M. ibiboboca, apresentadas neste trabalho, mostram aspectos semelhantes aos cariótipos de M. lemniscatus e M. surinamensis, únicas espécies deste gênero da América do Sul analisadas cromossomicamente. As quatro espécies em questão apresentam o mesmo número de microcromossomos (20), os maiores valores de macrocromossomos telocêntricos ou subtelocêntricos e os maiores números diplóides (2n) já encontrados no gênero Micrurus. Tais características diferenciam estas espécies da América do Sul das nove da América Central com cariótipos já estudados.

The karyotypes of two brazilian species of coral snakes (Ophidia: Elapidae): Micrurus corallinus and M. ibiboboca are described for the first time. Cytological preparations were obtained through the technique of squashing, followed by conventional Giemsa staining. The diploid number for Micrurus corallinus was 40 chromosomes with a karyotype formulae 40 (4; 16; 20) with a secondary constriction in the second pair of subtelocentric macrochromosomes. Micrurus ibiboboca is described by the formulae 42 (2; 20; 20) with 2n = 42 with a secondary constriction in the first pair of telocentric macrochromosomes. The karyotypes of M. corallinus and M. ibiboboca present aspects similar to M. lemniscatus and M. surinamensis, the only previously analyzed species of this genus in South America. These four species have the same number of microchromosomes (20), the largest number of telocentric or subtelocentric macrochromosomes and the largest diploid numbers (2n) ever found in the genus Micrurus. These characteristics differ from those of the nine known species of Central America.

Epidemiologia dos acidentes por serpentes peçonhentas no Estado do Ceará--Brasil / The epidemiology of accidental bites by venomous snakes in the state of Ceará, Brazil

Foram notificados à Secretaria de Saúde do Estado do Ceará, no período de 1992 a 1995, 688 acidentes causados por serpentes peçonhentas (média anual de 172 casos), com coeficiente de incidência variando entre 0,9 e 5,8 por 100.000 habitantes. Dentre 473 casos em que houve referência ao gênero da serpente 88,3% foram por Bothrops, 10,6% por Crotalus, 0,8% por Micrurus e 0,2% por Lachesis. Os meses de abril a setembro apresentaram maior incidência. Houve predominância de pacientes do sexo masculino (75,6%) e com idades entre 10 a 49 anos (72,3%). As regiões anatômicas mais freqüentemente picadas foram os membros inferiores (81,9%) e superiores (14,7%). O atendimento na unidade de saúde que notificou o acidente ocorreu dentro de seis horas em 66,9% dos casos. A letalidade foi de 0,7%. Os acidentados foram sobretudo agricultores (62,7%), a maioria dos casos ocorreu no próprio local de trabalho. Os autores reforçam que os acidentes ofídicos no Estado do Ceará podem ser considerados acidentes de trabalho, acometem principalmente os trabalhadores rurais e constituem causa de óbito.

From 1992 to 1995, 688 accidents by venomous snakes (mean of 192 cases/year) have been notified to the Health Ministry of the State of Ceará, with an incidence between 0.9 and 5.8/100.000 inhabitants. Among 473 cases, 88.3% were of the genus. Bothrops, 10.7% Crotalus, 0.8% Micrurus and 0.2% Lachesis. The highest incidence occurred from April to September. Male (75.6%) predominated with ages from 10 to 49 years old (72.3%). The more frequently bitten anatomical region were the lower limbs (81.9%) and upper limbs (14.7%). The attendance at health unit which notified the accident took place within 6 hours in 66.9% of the cases. Lethality was 0.7%. The afflicted people were mainly peasants (62.7%), and most of the accidents took place in their own work place. The authors emphasize that the snake bites in the state of Ceará may be considered work accidents, concern mainly peasants and constitute a cause of death.