Remote South American Snakebite with Extensive Myonecrosis

Epidemiology and clinical features of venomous snake bites in the Northern Amazon of Ecuador (2017-2021)

Introduction: In Ecuador, poisonous snakebites are a public health problem. However, there is no recent hospital information from the Amazon. Objective: To retrospectively analyse the clinical-epidemiological characteristics of snakebites in patients admitted to a hospital in the Ecuadorian Amazon. Materials and methods: This is a cross-sectional study conducted at the Nueva Loja-Sucumbíos Provincial Hospital, bordering Colombia (2017-2021). Demographic, epidemiological and clinical variables, and condition at hospital discharge, were obtained from the epidemiological file of the Ministerio de Salud Pública. Results: In 5 years, 147 patients (29.4 per year) were hospitalized with no mortality. They corresponded to 26, 34, 32, 29 and 26 cases, in 2017, 2018, 2019, 2020 and 2021, respectively. Men with 99 (67.3%), aged 21-30 years with 28, mixed race with 94 cases, students, and farmers, were the most affected. The most affected (99; 67.3%) were men, people 21 to 30 years-old (28; 19.0%), mestizos (94; 63.9%), students, and farmers. The median age was 28 (range: 4-81) years. Prevalence was higher in April, June, and September. All accidents were caused by Viperidae snakes. Twenty (13.6%) cases were mild, (61.2%) were moderate and 37 (25.2%) were severe. The feet with 45 were the most bitten. Pre-hospitalization anti-venom serum was received by 53.1% and tourniquet by 19.8% patients. Median hospital arrival time was 5 (range 1-192) hours, mostly between 2-3 hours with 41 cases. No statistically significant differences were found considering the severity. Conclusions: A high prevalence of snakebites was evidenced in the north of the Amazon in Ecuador, with a higher incidence in the rainy season and all by Viperidae species. It is important to highlight the null mortality. Information campaigns on prevention and first aid, such as discouraging the use of tourniquets, especially among vulnerable groups.

Biochemical characterization of Bothrops roedingeri Mertens, 1942 snake venom and its edematogenic, hemorrhagic, and myotoxic activities

Introduction: Snakebite envenoming is considered by the World Health Organization (WHO) as a neglected tropical disease. Currently, Bothrops snake venoms are being studied intensively, but there is little knowledge about Bothrops roedingeri venom. Objectives: To biochemically characterize B. roedingeri total venom and evaluate its myotoxic, edematogenic, and hemorrhagic activity. Materials and methods: We characterized B. roedingeri venom enzymatic activity by determining the phospholipase A2 and the proteolytic and fibrinogenolytic action using SDSPAGE electrophoresis while we characterized its venom toxicity by determining the minimum hemorrhagic dose, the minimum edema dose, and the local and systemic myotoxic effects. Results: Bothrops roedingeri venom showed a PLA2 activity of 3.45 ± 0.11 nmoles/min, proteolytic activity of 0.145 ± 0.009 nmoles/min, and a fibrinogen coagulation index of 6.67 ± 1.33 seconds. On the other hand, it produced an minimum hemorrhagic dose of 24.5 μg, an minimum edema dose of 15.6 μg, and a pronounced local myotoxic effect evidenced by the elevation of plasma creatine kinase levels after intramuscular inoculation. The venom showed no systemic myotoxicity. Conclusions: Bothrops roedingeri venom has local hemorrhagic, edematogenic, and myotoxic activity. Enzymatically, it has high PLA2 activity, which would be responsible for the myotoxic and edematogenic effects. It also has proteolytic activity, which could affect coagulation given its ability to degrade fibrinogen, and it causes bleeding through the metalloproteases.

Antivenom Neutralization of Coagulopathic Snake Venom Toxins Assessed by Bioactivity Profiling Using Nanofractionation Analytics

Venomous snakebite is one of the world's most lethal neglected tropical diseases. Animal-derived antivenoms are the only standardized specific therapies currently available for treating snakebite envenoming, but due to venom variation, often this treatment is not effective in counteracting all clinical symptoms caused by the multitude of injected toxins. In this study, the coagulopathic toxicities of venoms from the medically relevant snake species Bothropsasper, Calloselasmarhodostoma, Deinagkistrodonacutus, Daboiarusselii, Echiscarinatus and Echisocellatus were assessed. The venoms were separated by liquid chromatography (LC) followed by nanofractionation and parallel mass spectrometry (MS). A recently developed high-throughput coagulation assay was employed to assess both the pro- and anticoagulant activity of separated venom toxins. The neutralization capacity of antivenoms on separated venom components was assessed and the coagulopathic venom peptides and enzymes that were either neutralized or remained active in the presence of antivenom were identified by correlating bioassay results with the MS data and with off-line generated proteomics data. The results showed that most snake venoms analyzed contained both procoagulants and anticoagulants. Most anticoagulants were identified as phospholipases A2s (PLA2s) and most procoagulants correlated with snake venom metalloproteinases (SVMPs) and serine proteases (SVSPs). This information can be used to better understand antivenom neutralization and can aid in the development of next-generation antivenom treatments.