Trypanosoma sp. infection in Boa constrictor snakes: morphological, hematological, clinical biochemistry, molecular, and phylogenetic characteristics.

There are few reports of Trypanosoma in snakes, as well as little information about its pathogenicity in these animals. Thus, the present study aimed to characterize Trypanosoma found in Boa constrictor snakes, to verify the influence of the parasitism on hematological and clinical biochemistry parameters, and to perform a phylogenetic study of the isolates. Blood samples from sixty-one boas were analyzed for the presence of trypanosomatids and by hematological and clinical biochemistry assays. The flagellates that were found in this analysis were used for cell culture, morphometry, and molecular analysis. Later, molecular typing phylogenetic studies were performed. Nine positive animals (14.75%) were identified by microscopy analysis. The hematological results showed that parasitized animals presented significantly lower levels of packed cell volume, hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin. In the leukogram, eosinophils and heterophils counts were higher in parasitized animals. Considering the molecular analyses, the isolates presented a higher identity of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the 18S small subunit ribosomal RNA (SSU rRNA) gene fragments with Trypanosoma serpentis. The phylogenetic tree, using the GAPDH, clustered all isolates with T. serpentis and Trypanosoma cascavelli. This is the first description of T. serpentis parasitizing boas and of the clinical changes caused by trypanosomatid infection in snakes.

The absence of thrombin-like activity in Bothrops erythromelas venom is due to the deletion of the snake venom thrombin-like enzyme gene.

Snake venom thrombin-like enzymes (SVTLEs) are serine proteinases that clot fibrinogen. SVTLEs are distributed mainly in venoms from snakes of the Viperidae family, comprising venomous pit viper snakes. Bothrops snakes are distributed throughout Central and South American and are responsible for most venomous snakebites. Most Bothrops snakes display thrombin-like activity in their venoms, but it has been shown that some species do not present it. In this work, to understand SVTLE polymorphism in Bothrops snake venoms, we studied individual samples from two species of medical importance in Brazil: Bothrops jararaca, distributed in Southeastern Brazil, which displays coagulant activity on plasma and fibrinogen, and Bothrops erythromelas, found in Northeastern Brazil, which lacks direct fibrinogen coagulant activity but shows plasma coagulant activity. We tested the coagulant activity of venoms and the presence of SVTLE genes by a PCR approach. The SVTLE gene structure in B. jararaca is similar to the Bothrops atrox snake, comprising five exons. We could not amplify SVTLE sequences from B. erythromelas DNA, except for a partial pseudogene. These genes underwent a positive selection in some sites, leading to an amino acid sequence diversification, mostly in exon 2. The phylogenetic tree constructed using SVTLE coding sequences confirms that they are related to the chymotrypsin/kallikrein family. Interestingly, we found a B. jararaca specimen whose venom lacked thrombin-like activity, and its gene sequence was a pseudogene with SVTLE structure, presenting nonsense and frameshift mutations. Our results indicate an association of the lack of thrombin-like activity in B. jararaca and B. erythromelas venoms with mutations and deletions of snake venom thrombin-like enzyme genes.

Leptospira interrogans in wild Boa constrictor snakes from Northeast Brazil peri­urban rainforest fragments.

Leptospirosis, a disease that occurs worldwide, especially in tropical regions, is caused by bacteria of the genus Leptospira and affects mammals, amphibians, and reptiles. Boa constrictor snakes are commonly found in Atlantic rainforest fragments in peri­urban areas, which indicates a greater possibility of the contact of these animals with humans residing there. Therefore, the aim of this work was to detect Leptospira spp infection through molecular assays in wild B. constrictor snakes rescued in peri­urban areas and verify seroreactivity, by the microscopic agglutination test (MAT), as well as the most common serogroups. Among the 46 samples tested, 7 (15.21%) were positive according to PCR and confirmed as Leptospira interrogans through secY gene sequencing. In MAT, 37 (80.43%) of the 46 samples were classified as reactive. Panama was the serogroup with the highest occurrence. The results showed the presence of Leptospira spp DNA in asymptomatic snakes rescued in rainforest fragments located in peri­urban areas and support further investigations on the influence of these animals in the epidemiology of leptospirosis in tropical peri­urban areas.

Agriculture and snakebite in Bahia, Brazil - An ecological study.

This study investigated the correlation between the incidence of snakebite and indicators of agricultural development in municipal districts of the State of Bahia, Brazil. An ecological study was conducted with the 27,347 cases of snakebite poisoning reported to the Reportable Diseases National Information System in municipalities from the State of Bahia, Brazil, 2000-2009. The unit of analysis was each one of the 417 State municipalities, and the outcome variable was the average annual incidence of snakebite. Data were analyzed by multiple linear regression technique. The average annual incidence of snakebite ranged from zero to 221.96 per 100,000 inhabitants, according to the municipalities. The incidence of snakebite was positively and strongly associated with municipality characteristics: planted areas of cocoa and coffee, and the size of domestic bred chicken and bovine livestocks. It was concluded that several characteristics related to municipal agricultural profile were strongly associated with the incidence of snakebite.

Ocorrência de Rhopalurus debilis (C.L. Koch, 1840) (Scorpiones, Buthidae) no estado da Bahia, Brasil / x

Este trabalho assinala a ocorrência de Rhopalurus debilis (C.L. Koch, 1841), no estado da Bahia, Brasil, acrescentando mais uma espécie à sua escorpiofauna e reforçando a importância do estudo regionalizado desses animais. Sete escorpiões (2 machos, 4 fêmeas e 1 jovem) foram coletados no município de Curaçá (08° 59' 31"S/ 39° 54' 29"W), entre os dias 14 e 16 de março de 2003, registrados no Núcleo Regional de Ofiologia e Animais Peçonhentos da Bahia (NOAP) e tombados no Museu de Zoologia da Universidade Federal da Bahia. Este registro revela uma nova ocorrência desta espécie, na margem direita do rio São Francisco.

This work reports the occurrence of Rhopalurus debilis (C.L. Koch, 1840), in the state of Bahia, Brazil, adding a species to its escorpiofauna and highlighting the importance of carrying out regional studies on these animals. Seven scorpions (2 males, 4 females and 1 young) were collected in the city of Curaçá (08° 59° 31°S/39° 54° 29°W), from March 14th to 16th, 2003. They were recorded in the Núcleo Regional de Ofiologia e Animais Peçonhentos da Bahia (NOAP) and included in the Scientific Collection of Scorpions of the Federal University of Bahia. These specimens represent a new record of this species in the right riverbank of the São Francisco river.

Avaliação da DL50 e edema pulmonar induzido pelo veneno de Tityus serrulatus (Scorpiones; Buthidae) procedente da Bahia, Brasil / x

O escorpião Tityus serrulatus é conhecido como a espécie mais importante, do ponto de vista médico, pois é o que causa os acidentes mais graves registrados para o território brasileiro. Este trabalho trata da caracterização do veneno do escorpião T. serrulatus, através da obtenção da DL50 e determinação da capacidade em induzir edema pulmonar, em ratos. O veneno foi obtido através de estímulo elétrico. A toxicidade foi determinada através da avaliação da DL50, pelo método de Finney (1971). Os valores demonstraram a baixa toxicidade do veneno (96,16 mg/camundongo), que corresponde a 3 - 7 vezes menos tóxico que venenos de espécimes de outras regiões do Brasil. O veneno testado também não induziu edema pulmonar, avaliado através da diferença entre o peso do pulmão de animais experimentais e controle. Estes resultados demonstram uma variação do veneno de T. serrulatus e poderia explicar a ausência de óbitos e do registro de edema pulmonar nos pacientes picados nestas regiões do Estado da Bahia, Brasil.

Tityus serrulatus is the most important scorpion species, which cause most accidents and induces the most serious forms of poisoning in Brazil. In the present study we investigate the toxicity and pulmonary-edema induced ability of specimens from the metropolitan region of Salvador (RMS) and south-central Bahia (SCB), state of Bahia, Brazil. Male Swiss mice (18-22g) had been used to evaluate the toxicity by the Finney method (1971). The LDs50 tested in mice weighing 18-20 g was 96,16 mg/mice. This value represents 3 to 7 times lesser than the toxicity of T. serrulatus from other regions of Brazil. Also, the venom does not induce pulmonary edema, as assessed by the weight difference between the tested and control lung. Our results demonstrate marked variation in the lethal and the pulmonary-induced edema of Tityus serrulatus venom from RMS and SCB. These results could explain the absence of death and pulmonary complications of scorpion envenomation in some regions of Bahia, Brazil.

Effect of Bothrops leucurus venom in chick biventer cervicis preparations.

Bothrops leucurus is a poorly studied pitviper found in northeastern Brazil. We examined the action of B. leucurus venom (5-100 microg/ml) on contractile responses in chick biventer cervicis preparations. Muscle damage was assessed by quantifying the release of creatine kinase (CK) and by histological analysis. B. leucurus venom dose-dependently inhibited the contractile responses of indirectly stimulated preparations, the maximum inhibition with 100 microg of venom/ml being 74.0+/-6.6% (mean+/-SEM) after 120 min. The venom also reduced contractures to exogenous acetylcholine (55 and 110 microM) and K(+) (13.4mM) (85-100% reduction with 100 microg of venom/ml) and increased the release of CK (348+/-139 U/ml in controls vs 1260+/-263 U/ml with 20 microg of venom/ml after 120 min, p<0.05). The accompanying morphological changes included multivacuolated, swollen, amorphous fibers and agglutinated myofibrils. These results indicate that B. leucurus venom can adversely affect neuromuscular transmission and produce muscle damage in avian preparations.