Snakebite Associated Thrombotic Microangiopathy and Recommendations for Clinical Practice

Hump-Nosed Viper Bite-Associated Thrombotic Thrombocytopenic Purpura: A Rare Complication

Thrombotic thrombocytopenic purpura (TTP) is one of the rarely encountered complications of hump-nosed viper bites, which requires early detection and specific management. Hump-nosed viper bites are well known to affect multiple systems, and it is imperative to identify and manage each complication simultaneously. A 48-year-old patient presented to the hospital following a hump-nosed viper bite, where he subsequently developed local necrosis, acute kidney injury (AKI), and TTP. A diagnosis of TTP was made using the PLASMIC score (which refers to the score's seven components: platelet count; combined hemolysis variable; absence of active cancer; absence of stem-cell or solid organ transplant; mean corpuscular volume (MCV); international normalized ratio (INR); and creatinine) and supporting blood picture findings despite the diagnostic difficulties encountered due to the misleadingly normal automated platelet counts. The patient underwent multiple blood transfusions, 12 cycles of hemodialysis, and two cycles of therapeutic plasma exchange, the latter contributing to a significant improvement in his overall clinical and biochemical markers. In this case presentation, we report a rare case of TTP occurring after a hump-nosed viper bite, with the outcome of the report focusing on the diagnostic difficulties and available therapeutic modalities.

Thromboembolic events following a pit viper bite from Protobothrops mucrosquamatus (Taiwan Habu): A report of two cases

Protobothrops mucrosquamatus, also known as the Taiwan Habu, is a venomous snake prevalent in Taiwan. It is accountable for most snakebites in the region. The toxin of the Taiwan Habu has significant hemorrhagic potential. However, patients bitten by this snake often suffer more local injuries than systemic ones. This report presents two cases of individuals bitten by the Taiwan Habu who subsequently experienced thromboembolism. In the first case, an 88-year-old male, bitten on his fourth toe, suffered a cerebral infarction 32 hours post-bite. In the second case, an 82-year-old female, bitten on her ankle, experienced cardiac arrest 19 hours later. Both patients promptly received antivenom and showed no signs of coagulopathy either before or after the snakebite. However, elevated coagulation factor VIII levels were observed in the first case. Our aim is to understand the mechanism behind these thromboembolic events. This report emphasizes the unusually high level of coagulation factor VIIIa and highlights the need for further investigation into the mechanisms involved. Consequently, physicians should assess the risk of thromboembolic events in snakebite patients by evaluating coagulation factors during treatment.

The Presence of Four Pathogenic Oral Bacterial Species in Six Wild Snake Species from Southern Taiwan: Associated Factors

The oral cavity of snakes serves as a habitat for various microorganisms, some of which may include potential zoonotic pathogens posing risks to hosts and causing wound infections in snakebite victims. Clinical studies on snakebite cases in Taiwan have identified specific pathogens, such as Enterococcus faecalis (Gram-positive), Morganella morganii, Aeromonas hydrophila, and Pseudomonas aeruginosa (Gram-negative). However, the prevalence of these bacteria in the oral cavity of wild snakes remains largely unknown. This study investigated the occurrence of these bacteria in six wild snake species (Naja atra, Bungarus multicinctus, Trimeresurus stejnegeri, Protobothrops mucrosquamatus, Boiga kraepelini, and Elaphe taeniura friesi) from southern Taiwan, along with factors influencing their presence. Oropharyngeal swab samples were collected from a substantial number of wild-caught snakes (n = 1104), followed by DNA extraction, polymerase chain reaction, and gel electrophoresis. The band positions of samples were compared with positive and negative controls to determine the presence of target bacteria in each sample. The overall occurrence rates were 67.4% for E. faecalis, 31.5% for M. morganii, 8.2% for A. hydrophila, and 7.7% for P. aeruginosa. Among snake species, B. kraepelini exhibited dominance in E. faecalis (93.4%), A. hydrophila (17.1%), and P. aeruginosa (14.5%), while male N. atra showed dominance in M. morganii (51.3%). The occurrence of E. faecalis was lowest in winter. The results of multiple logistic regression analyses suggest that factors such as species, sex, temperature, season, and coexisting pathogens may have a significant impact on the occurrence of target bacteria. These findings have implications for wildlife medicine and snakebite management.

Clinical experience of late presentation and major limb complication of Snake bite: A case report and review

Snakebite is a significant global public health concern. Venomous snake bites can lead to various life-threatening clinical conditions that affect different bodily systems. These include the nervous system (neurotoxicity), musculoskeletal system (myotoxicity), cardiovascular system (cardiotoxicity), and blood clotting mechanisms (haemotoxicity). Here, we report a 5-year-old boy who was bitten by a snake and presented to the Emergency department with complaints of significant infection, necrosis, and gangrene affecting the three fingers of his right hand. After clinical evaluation and investigations, the patient underwent surgical intervention. The patient was discharged from the hospital after 5 weeks of admission with advice to follow up with a primary care physician and physical rehabilitation therapy to ensure the optimal healing and functionality of the affected hand.

Management of Snakebite-Induced Thrombotic Microangiopathy (TMA) With Plasmapheresis

Snakebites affect a lot of people in India. Of these, the hemotoxic snakebites may induce a consumptive coagulopathy, which has been termed now as "Venom-Induced Consumptive Coagulopathy" (VICC). Some patients with VICC develop Thrombotic Microangiopathy (TMA). The primary end-organ damage in TMA is renal, for which hemodialysis is the mainstay of treatment. Recently there has been some focus on plasma exchange as an adjunctive treatment for TMA. Here we present a case of a young male who developed snakebite-induced TMA and who was successfully managed with plasma exchange.

Biochemical and hemostatic description of a thrombin-like enzyme TLBro from Bothrops roedingeri snake venom

Objective: The current study's objective is to characterize a new throm-bin-like enzyme called TLBro that was obtained from Bothrops roedingeris snake from a biochemical and hemostatic perspective. Methodology: One chromatographic step was used to purify it, producing the serine protease TLBro. Molecular mass was estimated by SDS-PAGE to be between reduced and unreduced by 35 kDa. Tryptic peptide sequencing using Swiss Prot provided the complete amino acid sequence. Expasy.org by conducting a search that is limited to Crotalinae snake serine proteases and displaying a high degree of amino acid sequence. Results: Ser (182) is inhibited by phenylmethylsulfonyl fluoride (PMSF), and TLBro demonstrated the presence of Asp (88) residues. It also deduced the positions of His (43) and Ser (182) in the set of three coordinated amino acids in serine proteases. It was discovered that this substrate had high specificity for BANA, Michaelis-Menten behavior with KM 0 point85 mM and Vmax 1 point89 nmoles -NA/L/min, and high stability between temperatures (15 to 70°C) and pHs (2 point0 to 10 point0). According to doses and incubation times, TLBro degraded fibrin preferentially on the B-chain; additionally, its activities were significantly diminished after preincubation with divalent ions (Zn2 and Cd2). When incubated with PMSF, a particular serine protease inhibitor, enzymatic activities and platelet aggregation were inhibited. Conclusion: The findings revealed distinct structural and functional differences between the serine proteases, adding to the information and assisting in the improvement of the structure-function relationship.

Thromboelastographic evaluation in dogs with Asian pit viper (Gloydius) envenomation

The objective of this study was to investigate the thromboelastography (TEG) variables and platelet count after Asian pit viper (Gloydius) envenomation in dogs compared with healthy control dogs. Ten dogs with snake envenomation and twenty healthy dogs were included. There was a significant decrease in G (P=0.017), maximum amplitude (MA) (P=0.012), angle value (P=0.041), platelet count (P<0.001, as well as an increase in K value (P=0.034) and R value (P=0.007) in dogs with snake envenomation. The results of this study revealed that dogs with Asian pit viper (Gloydius) envenomation showed a hypocoagulable state compared with healthy dogs. Our findings may support the use of TEG for diagnosing and monitoring coagulopathy after Asian pit viper (Gloydius) envenomation in dogs.

Comparisons of the Oral Microbiota from Seven Species of Wild Venomous Snakes in Taiwan Using the High-Throughput Amplicon Sequencing of the Full-Length 16S rRNA Gene

A venomous snake's oral cavity may harbor pathogenic microorganisms that cause secondary infection at the wound site after being bitten. We collected oral samples from 37 individuals belonging to seven species of wild venomous snakes in Taiwan, including Naja atra (Na), Bungarus multicinctus (Bm), Protobothrops mucrosquamatus (Pm), Trimeresurus stejnegeri (Ts), Daboia siamensis (Ds), Deinagkistrodon acutus (Da), and alpine Trimeresurus gracilis (Tg). Bacterial species were identified using full-length 16S rRNA amplicon sequencing analysis, and this is the first study using this technique to investigate the oral microbiota of multiple Taiwanese snake species. Up to 1064 bacterial species were identified from the snake's oral cavities, with 24 pathogenic and 24 non-pathogenic species among the most abundant ones. The most abundant oral bacterial species detected in our study were different from those found in previous studies, which varied by snake species, collection sites, sampling tissues, culture dependence, and analysis methods. Multivariate analysis revealed that the oral bacterial species compositions in Na, Bm, and Pm each were significantly different from the other species, whereas those among Ts, Ds, Da, and Tg showed fewer differences. Herein, we reveal the microbial diversity in multiple species of wild snakes and provide potential therapeutic implications regarding empiric antibiotic selection for wildlife medicine and snakebite management.

Cortical Blindness and Thrombotic Microangiopathy Following a Hemotoxic Snake Envenomation: An Unusual Presentation

Snake envenomation leads to significant morbidity and mortality with local, hematological, renal, and neurological complications. Hemotoxic envenomation activates a hemorrhagic cascade, leading to many manifestations ranging from skin bleeds to major organ bleeds and fatal intracranial hemorrhage. Although rare, ischemic manifestations are possible following a hemotoxic envenomation, and they may present as cortical blindness, an unusual ocular symptom. Snake envenomation is also known to cause multifactorial acute kidney injury (AKI), precipitated by hemodynamic disturbances secondary to rhabdomyolysis, hemoglobinuria, direct tubular toxicity, and thrombotic microangiopathy. Thrombotic microangiopathy (TMA) is often overlooked in snake bites, as the hematological manifestations are often conveniently attributed to venom-induced consumptive coagulopathy (VICC). The distinct clinical entity of thrombotic microangiopathy should factor into one's differential diagnosis in patients presenting with microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury following a snake bite. We report a patient who developed cortical blindness and thrombotic microangiopathy following snake envenomation, which are uncommon sequelae.

Crosstalk of Inflammation and Coagulation in Bothrops Snakebite Envenoming: Endogenous Signaling Pathways and Pathophysiology

Snakebite envenoming represents a major health problem in tropical and subtropical countries. Considering the elevated number of accidents and high morbidity and mortality rates, the World Health Organization reclassified this disease to category A of neglected diseases. In Latin America, Bothrops genus snakes are mainly responsible for snakebites in humans, whose pathophysiology is characterized by local and systemic inflammatory and degradative processes, triggering prothrombotic and hemorrhagic events, which lead to various complications, organ damage, tissue loss, amputations, and death. The activation of the multicellular blood system, hemostatic alterations, and activation of the inflammatory response are all well-documented in Bothrops envenomings. However, the interface between inflammation and coagulation is still a neglected issue in the toxinology field. Thromboinflammatory pathways can play a significant role in some of the major complications of snakebite envenoming, such as stroke, venous thromboembolism, and acute kidney injury. In addition to exacerbating inflammation and cell interactions that trigger vaso-occlusion, ischemia-reperfusion processes, and, eventually, organic damage and necrosis. In this review, we discuss the role of inflammatory pathways in modulating coagulation and inducing platelet and leukocyte activation, as well as the inflammatory production mediators and induction of innate immune responses, among other mechanisms that are altered by Bothrops venoms.

Increased Binding of von Willebrand Factor to Sub-Endothelial Collagen May Facilitate Thrombotic Events Complicating Bothrops lanceolatus Envenomation in Humans

Consumption coagulopathy and hemorrhagic syndrome exacerbated by blood anticoagulability remain the most important causes of lethality associated with Bothrops snake envenomation. Bothrops venom also engages platelet aggregation on the injured endothelium via von Willebrand factor (vWF) interactions. Besides platelet aggregation, some Bothrops venom toxins may induce qualitative thrombopathy, which has been in part related to the inhibition of vWF activation. We tested whether B. lanceolatus venom impaired vWF to collagen(s) binding (vWF:CB) activity. Experiments were performed with B. lanceolatus crude venom, in the presence or absence of Bothrofav, a monospecific B. lanceolatus antivenom. Venom of B. lanceolatus fully inhibited vWF to collagen type I and III binding, suggesting venom interactions with the vWF A3 domain. In contrast, B. lanceolatus venom increased vWF to collagen type VI binding, suggesting the enhancement of vWF binding to collagen at the vWF A1 domain. Hence, B. lanceolatus venom exhibited contrasting in vitro effects in terms of the adhesive properties of vWF to collagen. On the other hand, the antivenom Bothrofav reversed the inhibitory effects of B. lanceolatus venom on vWF collagen binding activity. In light of the respective distribution of collagen type III and collagen type VI in perivascular connective tissue and the sub-endothelium, a putative association between an increase in vWF:CB activity for collagen type VI and the onset of thrombotic events in human B. lanceolatus envenomation might be considered.

Clinical aspects of snakebite envenoming and its treatment in low-resource settings

There is increasing recognition of the public health importance of snakebite envenoming. Worldwide annual incidence is likely to be 5 million bites, with mortality exceeding 150 000 deaths, and the resulting physical and psychological morbidity leads to substantial social and economic repercussions. Prevention through community education by trained health workers is the most effective and economically viable strategy for reducing risk of bites and envenoming. Clinical challenges to effective treatment are most substantial in rural areas of low-resource settings, where snakebites are most common. Classic skills of history taking, physical examination, and use of affordable point-of-care tests should be followed by monitoring of evolving local and systemic envenoming. Despite the profusion of new ideas for interventions, hyperimmune equine or ovine plasma-derived antivenoms remain the only specific treatment for snakebite envenoming. The enormous interspecies and intraspecies complexity and diversity of snake venoms, revealed by modern venomics, demands a radical redesign of many current antivenoms.

Longitudinal Metabolomics and Lipidomics Analyses Reveal Alterations Associated with Envenoming by Bothrops asper and Daboia russelii in an Experimental Murine Model

Longitudinal metabolomics and lipidomics analyses were carried out on the blood plasma of mice injected intramuscularly with venoms of the viperid species Bothrops asper or Daboia russelii. Blood samples were collected 1, 3, 6, and 24 h after venom injection, and a control group of non-envenomed mice was included. Significant perturbations in metabolomics and lipidomics were observed at 1, 3, and 6 h, while values returned close to those of control mice by 24 h, hence reflecting a transient pattern of metabolic disturbance. Both venoms induced significant changes in amino acids, as well as in several purines and pyrimidines, and in some metabolites of the tricarboxylic acid cycle. KEGG analysis of metabolic pathways that showed those with the greatest change included aminoacyl tRNA synthesis and amino acid biosynthesis and metabolism pathways. With regard to lipid metabolism, there was an increase in triglycerides and some acyl carnitines and a concomitant drop in the levels of some phospholipids. In addition, envenomed mice had higher levels of cortisol, heme, and some oxidative stress markers. The overall pattern of metabolic changes in envenomed mice bears similarities with the patterns described in several traumatic injuries, thus underscoring a metabolic response/adaptation to the injurious action of the venoms.

Disseminated Intravascular Coagulation: The Past, Present, and Future Considerations

Disseminated intravascular coagulation (DIC) has been understood as a consumptive coagulopathy. However, impaired hemostasis is a component of DIC that occurs in a progressive manner. The critical concept of DIC is systemic activation of coagulation with vascular endothelial damage. DIC is the dynamic coagulation/fibrinolysis disorder that can proceed from compensated to decompensated phases, and is not simply impaired hemostasis, a misunderstanding that continues to evoke confusion among clinicians. DIC is a critical step of disease progression that is important to monitor over time. Impaired microcirculation and subsequent organ failure due to pathologic microthrombi formation are the pathophysiologies in sepsis-associated DIC. Impaired hemostasis due to coagulation factor depletion from hemodilution, shock, and hyperfibrinolysis occurs in trauma-associated DIC. Overt-DIC diagnostic criteria have been used clinically for more than 20 years but may not be adequate to detect the compensated phase of DIC, and due to different underlying causes, there is no "one-size-fits-all criteria." Individualized criteria for heterogeneous conditions continue to be proposed to facilitate the diagnosis. We believe that future research will provide therapeutics using new diagnostic criteria. Finally, DIC is also classified as either acute or chronic, and acute DIC results from progressive coagulation activation over a short time and requires urgent management. In this review, we examine the advances in research for DIC.

A Retrospective Evaluation of Snake Envenomation in Dogs in South Korea (2004-2021)

Snake envenomation is a medical emergency capable of causing local and systemic complications. However, information on venomous snakebite in dogs in South Korea is scarce. In this study, fifty-nine dogs treated at a private veterinary clinic from 2004 to 2021 were retrospectively studied. The aim was to characterize the demographics, elapsed time between snakebite and veterinary clinic presentation, laboratory findings, clinical signs, treatments, adverse reactions to antivenom, and prognosis of venomous snakebite. Snakebite was mostly observed between 12 p.m. and 5 p.m. from April to October. On the days of envenomation, the weather conditions were mostly cloudy, followed by rain/precipitation, and least frequently fair weather. Grassland was the most common incident location, and leashed dog walking was the most frequent activity when snakebite occurred. The main local symptoms were edema, hemorrhagic discharge, cutaneous erythema, ulceration, and necrosis. Major systemic clinical signs were tachypnea, tachycardia, altered mentation, ptyalism, and hypotension. Based on the time interval between snakebite and presentation at the veterinary clinic, two groups were defined: <4 h (Group 1, 49.2%) and ≥4 h (Group 2, 50.8%). Systemic inflammation was more frequently observed in Group 2. The level of C-reactive protein at presentation (p = 0.036) and the highest-level during hospitalization (p = 0.023) were significantly elevated in Group 2 (≥4 h). The dogs in Group 2 displayed more frequent muscle damage (increased creatine kinase) than the dogs in Group 1, and a higher level of creatine kinase was associated with delayed (≥4 h) presentation after snakebite (p = 0.003). All of the dogs were treated symptomatically, and 34 dogs (58%) received antivenom. Treatment with antivenom showed no adverse reactions in this study. All of the treated dogs recovered. One dog was euthanized without any treatment due to respiratory distress, hypotension, and cost constraints. In conclusion, this study provides baseline information on venomous snakebite in dogs in South Korea. The prognosis was excellent, especially when the dogs were treated within 4 h.

Fibrinogenolysis in Venom-Induced Consumption Coagulopathy after Viperidae Snakebites: A Pilot Study

Envenomations that are caused by Viperidae snakebites are mostly accompanied by venom-induced consumption coagulopathy (VICC) with defibrination. The clinical course of VICC is well described; however, reports about its detailed effects in the hemocoagulation systems of patients are sparse. In this pilot study, we prospectively analyzed the changes in plasma fibrinogen that were caused by the envenomation of six patients by five non-European Viperidae snakes. Western blot analysis was employed and fibrinogen fragments were visualized with the use of specific anti-human fibrinogen antibodies. All of the studied subjects experienced hypo- or afibrinogenemia. The western blot analysis demonstrated fibrinogenolysis of the fibrinogen chains in all of the cases. Fibrinogenolysis was considered to be a predominant cause of defibrination in Crotalus, Echis, and Macrovipera envenomation; while, in the cases of VICC that were caused by Atheris and Calloselasma envenomation, the splitting of the fibrinogen chains was present less significantly.