Development of a membrane-disruption assay using phospholipid vesicles as a proxy for the detection of cellular membrane degradation

Snakebite envenoming is a global health issue that affects millions of people worldwide, and that causes morbidity rates surpassing 450,000 individuals annually. Patients suffering from snakebite morbidities may experience permanent disabilities such as pain, blindness and amputations. The (local) tissue damage that causes these life-long morbidities is the result of cell- and tissue-damaging toxins present in the venoms. These compounds belong to a variety of toxin classes and may affect cells in various ways, for example, by affecting the cell membrane. In this study, we have developed a high-throughput in vitro assay that can be used to study membrane disruption caused by snake venoms using phospholipid vesicles from egg yolk as a substrate. Resuspended chicken egg yolk was used to form these vesicles, which were fluorescently stained to allow monitoring of the degradation of egg yolk vesicles on a plate reader. The assay proved to be suitable for studying phospholipid vesicle degradation of crude venoms and was also tested for its applicability for neutralisation studies of varespladib, which is a PLA2 inhibitor. We additionally made an effort to identify the responsible toxins using liquid chromatography, followed by post-column bioassaying and protein identification using high-throughput venomics. We successfully identified various toxins in the venoms of C. rhodostoma and N. mossambica, which are likely to be involved in the observed vesicle-degrading effect. This indicates that the assay can be used for screening the membrane degrading activity of both crude and fractionated venoms as well as for neutralisation studies.

Deciphering the interactions of scopoletin and scopolin from Catunaregam nilotica roots against Naja nigricollis phospholipase A2 enzyme

Catuneragam nilotica has been used in ethnomedicine to treat snakebite, inflammation, and diarrhea among others. The aim of this research is to isolate, and characterize potential potential phospholipase A2 (PLA2) inhibitors from the roots of C. nilotica. The plant material was collected, authenticated, and sequentially extracted using solvents of increasing polarity starting from n-hexane, ethyl acetate, and methanol. The extracts as reported in our previous work, were screened in vitro for their inhibitory activity against PLA2 enzyme from N. nigricollis venom using acidimetric assay. In line with the bio-activity guided isolation, methanol extract (being the most active) was subjected to chromatographic separation using silica gel and sephadex LH-20 which resulted in the isolation and characterization of scopoletin, and scopolin; the compounds were able to inhibit the hydrolytic actions of PLA2 enzyme with percentage inhibition ranging from 67.82 to 100.00 % and 65.76-93.15 %, respectively while the standard Antisnake Venom (ASV) had 74.96-85.04 % after 10 min incubation at 37 °C. The molecular docking of the compounds against PLA2 enzyme was performed using Auto Dock Vina while ADME-Tox analysis was evaluated using swissADME and ProTox-II online servers; The findings indicated that both compounds were able to bind to the active site of PLA2 enzyme with high affinity (-6.5 to -6.2 kcal/mol) and they exhibited favorable drug-likeness and pharmacokinetic properties, and according to toxicity predictions, scopolin was found to be non-toxic (LD50 of 5000 mg/kg) while scopoletin has a slight chance of being toxic (LD50 of 3800 mg/kg). In conclusion, the findings of the research revealed that the roots of C. nilotica contains phytoconstituents with anti-PLA2 enzyme activity and thus, validates the ethnomedicinal claim of the use of the plant as herbal therapy against N. nigricollis envenomation.

Alkaloids from Siparuna (Siparunaceae) are predicted as the inhibitors of proteolysis and plasma coagulation caused by snake venom and potentially counteract phospholipase A2 activity of Bothrops jararaca

ETHNOPHARMACOLOGICAL RELEVANCE

Snakebite envenomation (SBE) is the world's most lethal neglected tropical disease. Bothrops jararaca is the species that causes the greatest number of SBEs in the South and Southeastern of Brazil. The main symptoms are local (inflammation, edema, hemorrhage, and myonecrosis) and systemic (hemorrhage, hemostatic alterations with consumptive coagulopathy, and death) effects. Species of the genus Siparuna, Siparunaceae, are used in folk and traditional medicine to treat SBE. However, limited information is available concerning Brazilian Siparuna species against SBE.

AIM OF THE STUDY

To investigate the correlation between the compounds present in the extracts of five Siparuna species as potential agents against proteolytic activity, plasma coagulation, and phospholipase A2 (PLA2) activity caused by B. jararaca venom, using data obtained by UHPLC-MS/MS, biological activity, and multivariate statistics.

MATERIALS AND METHODS

The ethanol extracts from leaves of S. ficoides, S. decipiens, S. glycycarpa, S. reginae, and S. cymosa were fractionated by liquid-liquid extraction using different solvents of increasing polarity (hexane, dichloromethane, ethyl acetate, and n-butanol), affording their respective extracts, totaling 25 samples that were assayed through in vitro plasma coagulation and proteolytic activity assays. Moreover, the extracts were analyzed by UHPLC-MS/MS, using electrospray ionization (ESI) and atmospheric-pressure chemical ionization (APCI) in negative and positive ionization modes. The data was processed in MZmine v. 2.53 and evaluated by multivariate statistical tests (PLS) using the software UnscramblerX v. 10.4. These data were also used to build molecular networks (GNPS), and some ions of interest could be annotated using the library of molecules on the GNPS platform.

RESULTS

A total of 19 extracts inhibited B. jararaca-induced plasma coagulation, with emphasis on S. cymosa and S. reginae (800 sec). The inhibition of the proteolytic activity was also promising, ranging from 16% (S. glycycarpa) to 99% (S. cymosa, S. decipiens, and S. reginae). In addition, most extracts from S. cymosa and S. reginae inhibited 70-90% of PLA2 activity. Based on data from positive mode APCI analyses, it was possible to obtain a statistic model with reliable predictive capacity which exhibited an average R2 of 0.95 and a Q2 of 0.88, indicating a robust fit. This process revealed five ions, identified as the alkaloids: coclaurine (1), stepholidine (2) O-methylisopiline (3), nornantenine (4) and laurolitsine (5). This is the first study to evidence the potential antivenom of alkaloids from Siparuna species.

CONCLUSIONS

Altogether, our results give support to the popular use of Siparuna extracts in SBE accidents, suggesting their potential as an alternative or complementary strategy against envenoming by B. jararaca venom. The predicted ions in the chemometric analysis for the assayed activities can also be correlated with the blocking activity and encourage the continuation of this study for possible isolation and testing of individual compounds on the used models.

Preclinical evaluation of single domain antibody efficacy in mitigating local tissue damage induced by Bothrops snake envenomation

Camelid single-domain antibodies (VHH) represent a promising class of immunobiologicals for therapeutic applications due to their remarkable stability, specificity, and therapeutic potential. To enhance the effectiveness of antivenoms for snakebites, various methods have been explored to address limitations associated with serum therapy, particularly focusing on mitigating local damage and ensuring sustainable production. Our study aimed to characterize the pharmacological profile and neutralization capacity of anti-Phospholipase A2 (PLA2) monomeric VHH (Genbank accessions: KC329718). Using a post-envenoming mouse model, we used intravital microscopy to assess leukocyte influx, measured CK and LDH levels, and conducted a histopathology analysis to evaluate VHH KC329718's ability to neutralize myotoxic activity. Our findings demonstrated that VHH KC329718 exhibited heterogeneous distribution in muscle tissue. Treatment with VHH KC329718 reduced leukocyte influx caused by BthTX-I (a Lys-49 PLA2) by 28 %, as observed through intravital microscopy. When administered at a 1:10 ratio [venom or toxin:VHH (w/w)], VHH KC329718 significantly decreased myotoxicity, resulting in a 35-40 % reduction in CK levels from BthTX-I and BthTX-II (an Asp-49 PLA2) and a 60 % decrease in CK levels from B. jararacussu venom. LDH levels also showed reductions of 60%, 80%, and 60% induced by BthTX-I, BthTX-II, and B. jararacussu venom, respectively. Histological analysis confirmed the neutralization potential, displaying a significant reduction in tissue damage and inflammatory cell count in mice treated with VHH KC329718 post B. jararacussu venom inoculation. This study underscores the potential of monomeric anti-PLA2 VHH in mitigating myotoxic effects, suggesting a promising avenue for the development of new generation antivenoms to address current therapeutic limitations.

Varespladib mitigates acute liver injury via suppression of excessive mitophagy on Naja atra envenomed mice by inhibiting PLA2

Snakebite envenomation often leads to severe visceral injuries, including acute liver injury (ALI). However, the toxicity mechanism remains unclear. Moreover, varespladib can directly inhibit phospholipase A2 (PLA2) in snake venom, but its protective effect on snakebite-induced ALI and the mechanism have not been clarified. Previous studies have shown that snake venom PLA2 leads to neuron cell death via reactive oxygen species (ROS), one of the initial factors related to the mitophagy pathway. The present study group also found that ROS accumulation occurred after Naja atra envenoming. Hematoxylin and eosin (H/E) staining and immunohistochemistry (IHC) were performed to identify the expression of inflammatory factors in the liver tissue, and flow cytometry and immunofluorescence were used to detect ROS levels and mitochondrial function. Immunofluorescence and western blotting were also used for detecting mitophagy pathway-related proteins. The results showed that N. atra bite induced ALI by activating mitophagy and inducing inflammation and that varespladib had a protective effect. Collectively, these results showed the pathological mechanism of ALI caused by N. atra bite and revealed the protective effect of varespladib.

Study of defensive behavior of a venomous snake as a new approach to understand snakebite

Snakebites affect millions of people worldwide. The majority of research and management about snakebites focus on venom and antivenom, with less attention given to snake ecology. The fundamental factor in snakebites is the snakes' defensive biting behavior. Herein we examine the effects of environmental variables (temperature, time of day, and human stimulus) and biological variables (sex and body size) on the biting behavior of a medically significant pit viper species in Brazil, Bothrops jararaca (Viperidae), and associate it with the epidemiology of snakebites. Through experimental simulations of encounters between humans and snakes, we obtained behavioral models applicable to epidemiological situations in the State of São Paulo, Brazil. We found a significant overlap between behavioral, morphological, environmental, and epidemiological data. Variables that increase snakebites in epidemiological data also enhance the tendency of snakes to bite defensively, resulting in snakebites. We propose that snakebite incidents are influenced by environmental and morphological factors, affecting the behavior of snakes and the proportion of incidents. Thus, investigating behavior of snakes related to snakebite incidents is a valuable tool for a better understanding of the epidemiology of these events, helping the prediction and, thus, prevention of snakebites.

Acute compartment syndrome and fasciotomy after a viper bite in Italy: a case report

BACKGROUND

Bites caused by European vipers are rare medical emergencies but can occasionally cause life-threatening complications. Viper venom causes local symptoms, which can be accompanied by systemic manifestations in severe cases. The local effects of snakebites include edema and, more rarely, necrosis and compartment syndrome. The consequences of envenomation are often more pronounced in children due to their smaller body size.

CASE PRESENTATION

We present the case of a 6-year-old girl who experienced multiple viper bites in the lower limb in northwest Italy. The girl received supportive care but progressed to develop compartment syndrome that required emergency fasciotomy. The patient's condition improved promptly after surgical decompression and administration of antivenom, but full recovery required prolonged hospitalization and rehabilitation.

CONCLUSIONS

This case highlights the importance of obtaining a timely assessment of the severity of viper envenomation without delaying the administration of antivenom in most serious cases. The presence of multiple bite marks on the patient is one factor that may help to predict the clinical severity of snakebites and anticipate symptom progression.

Snake Envenomation

Snakebite envenomation (SBE) in horses can have devastating outcomes. Tissue damage, cardiotoxicity, coagulopathy, and neurotoxicity can be concerns with SBE. Understanding the actions of venom components is important in developing a successful treatment plan. Antivenom is the mainstay of treatment. Long-term deleterious effects can occur including cardiac dysfunction and lameness.

The establishment and evaluation of a swine model of deinagkistrodon acutus snakebite envenomation

OBJECTIVE

To establish a preclinical large-animal model of Deinagkistrodon acutus snakebite envenomation and evaluate its feasibility.

METHODS

The venom of D. acutus (0 mg/kg, 1 mg/kg, 2 mg/kg, 5 mg/kg, or 10 mg/kg) was injected into the left biceps femoris of 11 male pigs. Then, the circumferences of the limbs were regularly measured, and changes in muscle injury biomarkers, blood parameters, coagulation function, vital organ function and injury biomarkers were regularly detected. At 24 h after venom injection, the animals were euthanized, and the pathological damage to the vital organs mentioned above was evaluated.

RESULTS

The two pigs receiving 10 mg/kg and 5 mg/kg snake venom died at 8 h and 12 h after injection, respectively. The remaining pigs were equally divided into 0 mg/kg, 1 mg/kg, and 2 mg/kg snake venom groups, and all of them survived to 24 h after injection. Compared with the pigs receiving 0 mg/kg snake venom, the pigs receiving 1 mg/kg or 2 mg/kg snake venom exhibited significant abnormities, including limb swelling; increased muscle injury biomarker creatine kinase (CK) and coagulation function indicators prothrombin time and D-dimer; and decreased blood routine indicator platelet and coagulation function indicator fibrinogen. Moreover, significant abnormalities in myocardial and cerebral function and injury biomarkers in the heart, brain, liver, kidney and intestine were also observed. In particular, the abnormalities mentioned above were significantly obvious in those pigs receiving 2 mg/kg snake venom. Pathological evaluation revealed that the morphology of muscle, heart, brain, liver, kidney, and intestine in those pigs receiving 0 mg/kg snake venom was normal; however, pathological damage was observed in those pigs receiving 1 mg/kg and 2 mg/kg snake venom. Similarly, the pathological damage was more severe in those pigs receiving 2 mg/kg snake venom.

CONCLUSION

The intramuscular injection of 2 mg/kg D. acutus venom seems to be an optimal dose for examining the preclinical efficacy of existing and novel therapeutics for treating D. acutus envenomation in pigs.

Long-term hospital care needs after Bothrops atrox envenomation with hemorrhagic stroke in the Brazilian Amazon: 'From social to physical death' - A case report

Hemorrhagic stroke is a severe complication reported in cases of Bothrops atrox snakebite envenomation. We report an unusual case of a patient who evolved with an intracranial hemorrhagic stroke and was in a coma for more than five years in a tertiary hospital located in Manaus, Amazonas. 52-year-old man, carpenter, resident in the rural area of the municipality of Tabatinga, located 1106 km from Manaus, capital of Amazonas, Brazil, victim of an accident involving Bothrops atrox evolution with cardiorespiratory arrest, acute kidney injury and hemorrhagic stroke. After 43 days of hospitalization in the ICU, he was transferred to the ward, without contact with the environment and family, sent for home treatment, however, without acceptance by family members. During a long hospital stay for a period of 6 years, totally dependent on special care, in a flexed position, using a tracheostomy and mechanical ventilation, diagnosed and treated for hospital infections throughout his hospitalization, he died due to bacterial pneumonia. Losses of autonomy can result in an individual being completely disconnected from social life - a "social death before physical death".

Distinct cardiotoxic effects by venoms of a spitting cobra (Naja pallida) and a rattlesnake (Crotalus atrox) revealed using an ex vivo Langendorff heart model

Here we describe the acute myocardial effects of an elapid (red spitting cobra, Naja pallida) and a viper (western diamondback rattlesnake, Crotalus atrox) venom using an ex vivo heart model. Our results reveal two different pathophysiological trajectories that influence heart function and morphology. While cobra venom causes a drop in contractile force, rattlesnake venom causes enhanced contractility and frequency that coincides with differences in myocellular morphology. This highlights the medical complexity of snake venom-induced cardiotoxicity.

Identification of poorly immunodepleted phospholipase A2 (PLA2) proteins of Bungarus fasciatus venom from Assam, India and evaluation of Indian polyvalent antivenom using third-generation antivenomics

Bungarus fasciatus also referred to as the Banded krait is a snake which possesses venom and belongs to the Elapidae family. It is widely distributed across the Indian subcontinent and South East Asian countries and is responsible for numerous snakebites in the population. B. fasciatus possesses a neurotoxic venom and envenomation by the snake results in significant morbidity and occasional morbidity in the victim if not treated appropriately. In this study, the efficacy of Indian polyvalent antivenom (Premium Serums polyvalent antivenom) was evaluated against the venom of B. fasciatus from Guwahati, Assam (India) employing the Third-generation antivenomics technique followed by identification of venom proteins from three poorly immunodepleted peaks (P5, P6 and P7) using LC-MS/MS analysis. Seven proteins were identified from the three peaks and all these venom proteins belonged to the phospholipase A2 (PLA2) superfamily. The identified PLA2 proteins were corroborated by the in vitro enzymatic activities (PLA2 and Anticoagulant activity) exhibited by the three peaks and previous reports of pathological manifestation in the envenomated victims. Neutralization of enzymatic activities by Premium Serums polyvalent antivenom was also assessed in vitro for crude venom, P5, P6 and P7 which revealed moderate to poor inhibition. Inclusion of venom proteins/peptides, which are non-immunodepleted or poorly immunodepleted, into the immunization mixture of venom used for antivenom production may help in enhancing the efficacy of the polyvalent antivenom.

Prolonged venom-induced consumptive coagulopathy following Mangshan pit viper (Protobothrops mangshanensis) envenomation despite Hemato Polyvalent antivenom administration

This case report summarizes an envenomation by the Mangshan pit viper (Protobothrops mangshanensis), a rare, endangered, venomous snake endemic to Mount Mang of China, and the first reported use of Hemato Polyvalent antivenom (HPAV) for this species. The snakebite occurred in a United States zoo to a 46-year-old male zookeeper. He presented via emergency medical services to a tertiary center after sustaining a single P. mangshanensis bite to the abdomen and was transported with antivenom from the zoo. Within 2 hours of envenomation, he developed oozing of sanguineous fluid and ecchymosis at the puncture site, and about 4 hours post-bite, was treated with HPAV. His coagulation profile fluctuated with the following pertinent peak/nadir laboratory values and corresponding hospital day (HD): undetectable fibrinogen levels, d-dimer 8.89 mg/L and 7.43 mg/L, and INR 2.97 and 1.46 on HD zero and three, respectively. Other peak/nadir values included hemoglobin 9.7 g/dL and creatinine phosphokinase 2410 U/L on HD four and platelets 81 × 109/L on HD seven. The patient received a total of 30 vials of HPAV over 5 days and 1 unit of cryoprecipitate on HD six. Upon discharge on HD eight, laboratory studies were normalizing, except for platelets, and edema stabilized. This case describes an acute, recurrent, and prolonged venom-induced consumptive coagulopathy despite prompt administration and repeated doses of HPAV.

Toxinological profile and histopathological alterations induced by Bothrocophias campbelli venom from Colombia

Snakebite envenomings most frequently reported in Colombia are caused by snakes of the genera Bothrops, Bothriechis, Bothrocophias, and Porthidium. Their venoms induce local and systemic pathophysiological effects, sometimes leading to permanent sequelae such as reduced mobility of the limbs, amputations, besides the risk of death. The genus Bothrocophias includes nine species, among which B. campbelli has a distribution restricted to the department of Nariño in Colombia. In this work we determined the toxinological profile its venom, by performing assays for the lethal, hemorrhagic, edematogenic, and myotoxic activities in mouse models, as well as for in vitro coagulant activity on human plasma. The lethal toxicity of the venom was 142.7 µg venom/mouse (111.4-179.8 µg/mouse; 6.6-10.6 µg/g body weight) by intraperitoneal route. Its hemorrhagic activity (minimum hemorrhagic dose: 12.7 ± 2.3 µg) is generally weaker compared to other South American vipers, but edematogenic (minimum edematogenic dose 1.0 ± 0.3 µg), and myotoxic (minimum myotoxic dose 3.9 ± 2.5 µg) activities are very potent. Histopathological examination of the injected mouse gastrocnemius muscle showed prominent disorganization of the myofibrils, myonecrosis, and an intense inflammatory leukocyte infiltrate. In vitro, the minimal coagulant dose was 12.3 ± 0.5 µg. Overall, this toxinological profile would predict that the clinical picture of envenomings by B. campbelli might be characterized by moderate disturbances in the coagulation cascade, mild local hemorrhage, and, conversely, severe myonecrosis and edema, which could potentially lead to compartment syndrome and gangrene.

Systematic review and meta-analysis on the efficacy of Indian polyvalent antivenom against the Indian snakes of clinical significance

Snakebite in India is a severe problem as it causes a mortality rate of 58,000 and a disability rate of 140,000 every year which is the highest among any other country. Antivenom is the primary therapy for snakebite, and its manufacturing techniques have essentially stayed unaltered for over a century. Indian polyvalent antivenom, a scientifically validated medicine for treating the toxic effects of snakebites, is available against the venom of the so-called Big Four snakes namely Spectacled cobra (Naja naja), Saw-scaled viper (Echis carinatus), Russell's viper (Daboia russelli) and the Common krait (Bungarus caeruleus), responsible for majority of the deaths in India. India hosts many other species of snakes, including cobras, kraits, saw-scaled vipers, sea snakes, and pit vipers, responsible for clinically severe envenomation. Neutralization strategy has been applied to access the efficacy of antivenoms, crucial for reducing snake bite deaths and disabilities. This review aims to conduct a systematic review and meta-analysis on the neutralization efficiency of the Polyvalent Antivenom (PAV) and focus on the factors that may contribute to the poor recognition of the antivenom towards the venom toxins. Reports focusing on the investigation of antivenom efficacy were searched and collected from several databases. Preclinical studies that reported the neutralization efficacy of the commercial antivenom against the medically important snakes of India were included. The articles were screened based on the inclusion criteria and 8 studies were shortlisted for meta-analysis. Pooled proportion was calculated for the antivenom efficacy reported by the studies and was found to be statistically significant with a 95% confidence interval. The heterogenicity in the venom toxicity and neutralization potency of the antivenom was evident in the overall estimate (proportion) and individual data. We provide comprehensive evidence on antivenom efficacy against medically important snakes from various parts of India which may aid in identifying the gaps in snake envenomation therapy and the need for novel potentially improved treatment of snakebites.

A confirmed human fatality due to envenomation by the Kunene Coral Snake (Aspidelaps lubricus cowlesi) in Namibia

Shield-nose and Coral snakes (Aspidelaps spp.) are medium sized venomous snakes found throughout southern Africa. Little is known about the venom of these snakes and its clinical relevance, as human bites are uncommon. Neurological signs and symptoms usually develop following bites by this genus but evaluations of the severity are inconclusive. We report on the first confirmed human fatality by the Kunene Shield-nose Snake (Aspidelaps lubricus cowlesi) in a child. Envenomation by Aspidelaps and other snakes considered lesser-venomous - especially those possessing neurotoxic venom - should be treated with caution as they may result in life-threatening envenomation without established clinical management protocols.

Recombinant human scFv antibody fragments against phospholipase A2 from Naja naja and Echis carinatus snake venoms: In vivo neutralization and mechanistic insights

Snake envenomation results in a range of clinical sequelae, and widely used animal-based conventional antivenoms exhibit several limitations including the adverse immunological effects in human snake bite victims. Therefore, human monoclonal anti-snake venom antibodies or fragments can be an alternate therapy for overcoming the existing limitations. We developed venom-neutralizing humanized scFv antibodies and analyzed biochemical mechanisms associated with the inhibition of toxicity. Tomlinson I and J human scFv antibody libraries were screened against Naja naja and Echis carinatus venoms, and seven unique scFv antibodies were obtained. Further, specific toxins of snake venom interacting with each of these scFvs were identified, and phospholipase A2 (PLA2) was found to be prominently captured by the phage-anchored scFv antibodies. Our study indicated PLA2 to be one of the abundant toxins in Naja naja and Echis carinatus venom samples. The scFvs binding to PLA2 were used to perform in vivo survival assay using the mouse model and in vitro toxin inhibition assays. scFv N194, which binds to acidic PLA2, protected 50% of mice treated with Naja naja venom. Significant prolongation of survival time and 16% survival were observed in Echis carinatus venom-challenged mice treated with scFv E113 and scFv E10, respectively. However, a combination comprised of an equal amount of two scFvs, E113 and E10, both interacting with basic PLA2, exhibited synergistically enhanced survival of 33% in Echis carinatus venom-challenged mice. No such synergistically enhanced survival was observed in the case of combinatorial treatment with anti-Naja naja scFvs, N194, and N248. These scFvs demonstrated partial inhibition of venom-induced myotoxicity, and E113 also inhibited hemolysis by 50%, which corroborates the enhanced survival during combinatorial treatment in Echis carinatus venom-challenged mice.

Hemoperitoneum after a Bothrops snakebite: Case report

Snakebites are frequent in tropical countries. Brazil has an average of 27,000 cases per year, with a fatality rate of 0.5%, and the Bothrops genus is the most common causative agent, accounting for about 70-90% of the accidents. This report describes a case of human envenomation by a juvenile Bothrops jararaca snake in São Paulo, Brazil, in a 71 years-old man, previously healthy. He presented a life-threatening envenomation, which developed to severe hypotension, acute kidney injury and extensive peritoneal hemorrhage. The hemoperitoneum was diagnosed due to persistent hypotension associated with anemia, pain and gastrointestinal complaints. Abdominal Computed Tomography scans showed a moderate to large amount of presumable hematic material inside the abdominal cavity, predominantly in the perihepatic and perisplenic spaces. The intra-abdominal hemorrhage was not surgically addressed, and the patient was discharged 5 days after hospitalization, with the progressive absorption of the hemoperitoneum. Systemic bleeding is one of the complications and main causes of death in Bothrops envenomations. Acute peritoneal hemorrhage is one of these serious complications that must be carefully addressed since its management must take into account the risk of bleeding caused by toxins that affect hemostasis. The case described highlights the importance of early diagnosis and adequate management of this potentially fatal complication in snakebites.

Scaling up antivenom for snakebite envenoming in the Brazilian Amazon: a cost-effectiveness analysis

Background

Snakebite envenoming (SBE) affects nearly three million people yearly, causing up to 180,000 deaths and 400,000 cases of permanent disability. Brazil's state of Amazonas is a global hotspot for SBE, with one of the highest annual incidence rates per 100,000 people, worldwide. Despite this burden, snake antivenom remains inaccessible to a large proportion of SBE victims in Amazonas. This study estimates the costs, and health and economic benefits of scaling up antivenom to community health centers (CHCs) and hospitals in the state.

Methods

We built a decision tree model to simulate three different antivenom scale-up scenarios: (1) scale up to 95% of hospitals, (2) scale up to 95% of CHCs, and (3) scale up to 95% of hospitals and 95% of CHCs. We consider each scenario with and without a 10% increase in demand for antivenom among SBE victims. For each scenario, we model the treatment costs averted, deaths averted, and disability-adjusted life years (DALYs) averted from a societal, health system, and patient perspective relative to the status quo and over a time horizon of one year. For each scenario and perspective, we also calculate the incremental cost per DALY averted and per death averted. We use a willingness to pay threshold equal to the 2022 gross domestic product (GDP) per capita of Brazil.

Findings

Scaling up antivenom to 95% of hospitals averts up to 2022 DALYs, costs up to USD $460 per DALY averted from a health system perspective, but results in net economic benefits up to USD $4.42 million from a societal perspective. Scaling up antivenom to 95% of CHCs averts up to 3179 DALYs, costs up to USD $308 per DALY averted from a health system perspective, but results in net economic benefits up to USD $7.35 million from a societal perspective. Scaling up antivenom to 95% of hospitals and CHCs averts up to 3922 DALYs, costs up to USD $328 per DALY averted from a health system perspective, but results in net economic benefits up to USD $8.98 million from a societal perspective.

Interpretation

All three antivenom scale up scenarios - scale up to 95% of hospitals, scale up to 95% of CHCs, and scale up to 95% of hospitals and 95% of CHCs - avert a substantial proportion of the SBE burden in Amazonas and are cost-saving from a societal perspective and cost-effective from a health system perspective.

Funding

W.M. and J.S. were funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq productivity scholarships). W.M. was funded by Fundação de Amparo à Pesquisa do Estado do Amazonas (PRÓ-ESTADO, call n. 011/2021-PCGP/FAPEAM, call n. 010/2021-CT&I ÁREAS PRIORITÁRIAS, call n. 003/2022-PRODOC/FAPEAM, POSGRAD/FAPEAM) and by the Ministry of Health, Brazil (Proposal No. 733781/19-035). Research reported in this publication was supported by the Fogarty International Center of the National Institutes of Health under Award Number R21TW011944. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Impact of tourniquet use on severity of snakebite envenoming in Chongqing, China: a single-center retrospective study

OBJECTIVE

To identify risk factors associated with snakebite severity and determine whether tourniquet use can affect the severity and outcome of snakebites.

METHODS

The clinical data of patients who sustained limb snakebites from 1 March 2021 to 31 October 2022 were reviewed. The patients were divided into three groups according to snakebite severity: mild (517 cases), moderate (112 cases), and severe (8 cases). We compared the clinical data of mild versus moderate to severe snakebites. Multivariate logistic regression was used to determine the independent risk factors for moderate to severe snakebites.

RESULTS

The study involved 637 patients. There were statistically significant differences in age, tourniquet use, onset time, white blood cell increase, platelet decrease, creatine kinase (CK) increase, activated partial thromboplastin time shortening, and length of stay between patients with mild snakebites and those with moderate to severe snakebites. Multivariate logistic regression analysis showed that age, tourniquet use, and CK increase were independent risk factors for moderate to severe snakebites.

CONCLUSION

The overall severity of snakebites in Chongqing is mild, and the prognosis is good. Age, tourniquet use, and CK increase are independent risk factors for the severity of snakebites. We do not recommend tourniquet use after snakebites in Chongqing.

[Assessment of a therapeutic protocol for the management of snakebite envenomations in Benin]

Introduction

Snakebite envenomation is a major public health issue in Sub-Saharan Africa (SSA). Antivenoms are the only etiological treatment. However, the dose recommended by the manufacturer (2 vials renewed every 2 hours in case of persistent bleeding) is usually not applied due to the high cost which is borne only by the patient. Based on clinical presentation, we evaluated the administration of a single vial on admission (instead of 2 vials), which corresponds to the therapeutic protocol used in current practice in most health centers in Benin and beyond in SSA. Renewal of antivenom followed manufacturer's recommendation.

Material and method

The study took place in a first referral hospital in Tanguiéta, North Benin. All envenomed patients received a slow intravenous vial of Inoserp® Pan-Africa (IPA) upon arrival. A clinical assessment identical to that of inclusion was carried out 2, 4, 6, 12 and 24 hours later to assess the tolerance and efficacy of the IPA, as well as the need to readminister the antivenom. The occurrence, persistence or worsening of clinical hemorrhages or neurological disorders, the latter reflecting envenomation by elapids, systematically led to the injection of 2 or 4 vials of IPA, respectively. Signs of intolerance were sought before and after each administration of antivenom, then 2 weeks to 1 month after treatment, in order to estimate the incidence of adverse effects attributable to the antivenom. Efficacy of IPA was assessed by cessation of bleeding and/or normalization of whole blood coagulation test (WBCT) within 24 hours of initial administration.

Results

The study took place from July 31 to October 31, 2019. We received 53 cases of snakebites of which 43 were included. The median age was 21 [IQR: 18-31] years and the sex ratio (M/F) was 1.5. Farmers were the majority (48%). The median time to admission was 1 [IQR: 0-2] day. On admission, 32 patients (74%) presented hemostasis disorders marked by bleeding and/or abnormal WBCT. None of the patients showed neurological symptoms. The median time to normalization of WBCT was 24 [IQR: 4-72] hours. The median time to stop bleeding was 6 [IQR: 4-12] hours. In 3 of the 11 patients whose bleeding had stopped at H2, a recurrence occurred within the following 24 hours. In addition, 3 patients presented with late bleeding 24 hours after admission. Two patients (5%) died as a result of envenomation.

Discussion/conclusion

The simplified protocol represents a significant saving in the number of vials used, i.e. 1.8±0.4 vials per patient instead of the 2.4±0.2 which would have been necessary in these same patients treated according to the standard protocol (p = 2.6·10-4). However, in comparison with the results obtained during the previous clinical study, the cessation of bleeding is delayed, as is the normalization of the WBCT at the different follow-up times. In addition, the number of re-administrations of antivenom after H2 is higher in the light protocol than in the standard one, respectively 13 patients out of 43 treated versus 4 patients out of 59 (p = 0.006). There was no significant difference between the incidence of signs of early antivenom intolerance in this study compared to the previous one (16% and 11%, respectively; p = 0.79). This delay can put up to a third of patients at risk of complications. Despite its effectiveness and the antivenom savings made, it does not seem reasonable to recommend it.

Evaluation of the role of neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR) and mean platelet volume (MPV) time series as predictors of diagnosis and prognosis of hemotoxic snakebite

BACKGROUND

This study aimed to assess the predictive value of NLR, PLR, and MPV time series for diagnosis and prognosis of hemotoxic snakebite envenomation.

METHODS

This is a prospective study among snakebite patients admitted to the Poison Control Center of Ain Shams University Hospitals and Assiut University Hospitals from the beginning of July 2019 to the end of October 2021. Patients were classified according to their clinical severity into three groups: mild, moderate, and severe.

RESULTS

The maximum incidence of snakebite was found in males (95%) from rural areas (80%); at lower limbs (70%); at night (51%); and during the autumn season (43.3%). The admission NLR and PLR can predict hemotoxic snakebite envenomation with an AUC of 0.940 and 0.569. The combination of NLR with PLR can develop a more predominant prediction of snakebite envenomation with an area under the curve (AUC) of 0.979. Furthermore, higher admission NLR and PLR levels are associated with prolonged hospital stays.

CONCLUSION

While NLR and PLR levels may be helpful in the diagnosis of snakebite, MPV plays no part in the prognosis of snakebite patients. Serial NLR, PLR initially, at 24 hours, and predischarge can be used to evaluate the early treatment response.

Considerations for the development of a field-based medical device for the administration of adjunctive therapies for snakebite envenoming

The timely administration of antivenom is the most effective method currently available to reduce the burden of snakebite envenoming (SBE), a neglected tropical disease that most often affects rural agricultural global populations. There is increasing interest in the development of adjunctive small molecule and biologic therapeutics that target the most problematic venom components to bridge the time-gap between initial SBE and the administration antivenom. Unique combinations of these therapeutics could provide relief from the toxic effects of regional groupings of medically relevant snake species. The application a PRISMA/PICO literature search methodology demonstrated an increasing interest in the rapid administration of therapies to improve patient symptoms and outcomes after SBE. Advice from expert interviews and considerations regarding the potential routes of therapy administration, anatomical bite location, and species-specific venom delivery have provided a framework to identify ideal metrics and potential hurdles for the development of a field-based medical device that could be used immediately after SBE to deliver adjunctive therapies. The use of subcutaneous (SC) or intramuscular (IM) injection were identified as potential routes of administration of both small molecule and biologic therapies. The development of a field-based medical device for the delivery of adjunctive SBE therapies presents unique challenges that will require a collaborative and transdisciplinary approach to be successful.

An ischemic complication of a snake bite: Case report

INTRODUCTION AND IMPORTANCE

Snakebite is a common type of animal bite injury worldwide. The local effect can manifest as an abscess followed by cellulitis and compartment syndrome which could cause ischemic tissue damage.

CASE PRESENTATION

A case of a 40-year male with a history of a snake bite 4 days back complained of swelling, throbbing pain, bluish discoloration of the skin and blackish discoloration of the little finger. Incision and drainage were done initially with disarticulation of the gangrenous little finger and finally treated with a split-thickness graft.

CLINICAL DISCUSSION

Snakebite can lead to only the bite mark without clinical features, local manifestations around the bite site, systemic toxicity due to redistribution of venom and signs and symptoms due to traditional treatment. Delayed presentation and improper treatment can lead to wound infection, abscess, compartment syndrome, necrotizing fasciitis and gangrene.

CONCLUSION

Snakebite is common in rural areas around the tropical world. Complications like compartment syndrome, necrotizing fasciitis and gangrene could develop following snake bite for which immediate surgical intervention is required to prevent loss of limb and life.

Renal functional and structural alterations induced by intramuscular injection of Bothrops leucurus venom

Acute kidney injury (AKI) is the main cause of death from Bothrops snakebite. Although many studies have investigated the nephrotoxicity induced by other Bothrops species, no study has assessed the renal alterations induced by intramuscular (i.m.) injection of Bothrops leucurus venom. In this study, we evaluated the nephrotoxicity induced by B. leucurus venom by analyzing renal function and histology. Wistar rats were submitted to i. m. injection of B. leucurus venom or saline and divided into two groups: Control group (C), rats submitted to i. m. injections of saline, and B. leucurus group (Bl), rats submitted to i. m. injections of B. leucurus venom (1 mg/kg). After venom or saline injection, serum and urine were collected to measure creatinine, albumin, sodium, and potassium levels. The glomerular filtration rate (GFR), urinary flow urinary, creatinine/serum creatinine ratio, and albuminuria-urinary creatinine ratio were determined. All rats were euthanized 72 h following the injections, and the kidneys were removed for histology and immunohistochemical studies. B. leucurus experimental envenoming was accompanied by an increase of 236% in serum creatine kinase activity in the Bl group. The weights of the right and left kidneys were, respectively, 26 and 22% higher in rats of the Bl group than in control rats. Regarding renal function, the Bl group showed a decrease of 37% in GFR compared to control group. The rats of the Bl group also presented increased cortical (8.20 ± 1.35) and medullar (6.17 ± 2.00) tubulointerstitial lesion area when compared to control group (0.02 ± 0.00) (1.20 ± 0.73), respectively. The number of macrophages was also higher in the renal cortex (6.66 ± 0.06) and medulla (1.22 ± 0.10) of rats from the Bl group when compared to control rats (1.04 ± 0.55), (0.65 ± 0.10), respectively. Our results indicate that B. leucurus venom promoted significant histological and functional renal alterations following intramuscular inoculation, which simulates the majority of snakebites observed in the clinical practice.

Kounis syndrome after anti-snake venom intradermal skin test: A case report

Snake bites are a concerning health problem in Egypt and other tropical countries that are effectively managed with anti-snake venom (ASV). ASV has common reactive complications that are usually mild. Rarely, anaphylaxis and severe systemic reactions may occur following ASV. In this case report, we present a rare condition of Kounis syndrome, acute allergic myocardial infarction, in a young man during anaphylaxis following an allergic intradermal test of VACSERA snake antivenom.

Antibiotic susceptibility of cultivable microbiota from the oral cavity of captive Bothrops atrox and Bothrops lanceolatus: Implications for the treatment of snakebite-associated infections in the French departments of America

INTRODUCTION

Secondary infection is a frequent complication after bites by Bothrops atroxin French Guiana or B. lanceolatus in Martinique. Knowledge of the bacteria present in snake mouths is a valuable aid for determining probabilistic antibiotherapy after Bothrops bite. The objectives of this study were to describe the cultivable bacteria of the oral microbiota of the specimens of B. atrox and B. lanceolatus kept in captivity, and to study their susceptibility to antibiotics.

METHODS

Fifteen B. atrox and 15 B. lanceolatus were sampled. Bacterial cultures were performed and each morphotype on plates was identified using MALDI-TOF mass spectrometry. Antibiotic susceptibility was studied using the agar disk diffusion method, with possible determination of the MICs.

RESULTS

One hundred and twenty-two isolates were identified: 52 isolates and 13 species in B. atrox, 70 isolates and 23 species in B. lanceolatus. The main species were Providencia rettgeri, Morganella morganii, Pseudomonas aeruginosa, Staphylococcus xylosus, and Paeniclostridium sordellii (only in B. lanceolatus mouths). For B. atrox, 96% of isolates were susceptible to piperacillin/tazobactam, cefepime, imipenem and meropenem, 94% to ciprofloxacin and 76% to cefotaxime and ceftriaxone. For B. lanceolatus, 97% of isolates were susceptible to meropenem, 96% to cefepime, 93% to imipenem and piperacillin/tazobactam, 80% to ciprofloxacin, and 75% to cefotaxime and ceftriaxone. Many isolates were resistant towards amoxicillin/clavulanate.

CONCLUSION

Among currently recommended antibiotics, cefepime and piperacillin/tazobactam seem more suitable than cefotaxime or ceftriaxone in the event of a Bothrops bite. Ciprofloxacin may also be considered for B. atrox.

Case fatality rate and burden of snakebite envenoming in children - A systematic review and meta-analysis

Snakebite is a major public health problem with an estimated global burden of 5 million people per annum. Data on snakebite envenoming in children are very limited and is unclear whether there is a significant difference in severity between adults and children. We therefore conducted a meta-analysis of observational studies on snakebite in children to obtain a more precise estimate of case fatality rate (CFR) as well as to explore the differences in outcome between children and adults. Studies from all over the world reported until the end of February 2023 were included. Analysis was conducted consistent with the Meta-analysis of Observational Studies in Epidemiology (MOOSE) criteria. Estimates were obtained from Random Effects Model (REM). Sub-analysis was conducted for studies from sub-Saharan Africa (SSA) to provide estimates for the continent. Adverse outcomes comprising composite endpoints (CE), defined as fatality and or complications, were compared between children and adults in sub-analysis of studies reporting on both groups. The annual burden and fatality of snakebite envenoming were derived based on lifetime prevalence of bite, meta-analysis estimates, and other data inputs. The pooled estimate of the CFR from 35 studies included worldwide was 1.98% [95%CI:1.38-2.58%] while the estimates from 6 studies within SSA was 2.43% (95%CI:0.67-4.20%). The odds of adverse outcomes were 2.52 times higher in children compared to adults. The estimated annual burden was 178,491 cases with 4346 deaths among children in SSA. These estimates compare favorably to those reported in the literature.

[A global core outcome measurement set for snakebite clinical trials]

Background

Snakebite clinical trials have often used heterogeneous outcome measures and there is an urgent need for standardisation.

Method

A globally representative group of key stakeholders came together to reach consensus on a globally relevant set of core outcome measurements. Outcome domains and outcome measurement instruments were identified through searching the literature and a systematic review of snakebite clinical trials. Outcome domains were shortlisted by use of a questionnaire and consensus was reached among stakeholders and the patient group through facilitated discussions and voting.

Results

Five universal core outcome measures should be included in all future snakebite clinical trials: mortality, WHO disability assessment scale, patient-specific functional scale, acute allergic reaction by Brown criteria, and serum sickness by formal criteria. Additional syndrome-specific core outcome measures should be used depending on the biting species.

Conclusion

This core outcome measurement set provides global standardisation, supports the priorities of patients and clinicians, enables meta-analysis, and is appropriate for use in low-income and middle-income settings.

First report of envenomation symptoms caused by the Eastern Montpellier snake, Malpolon insignitus (St.-Hilaire, 1827)

Snakebite is a global health problem with disastrous consequences. Accordingly, venoms plus their function and clinical aspects were intensively studied for several snakes, primarily with proteroglyphous and solenoglyphous dentition. Much less is known about the venoms from most opisthoglyphous (rear-fanged) snakes and it is often questionable which symptoms they may cause. Here, we provide the first description of the envenomation symptoms caused by a bite of the Eastern Montpellier snake Malpolon insignitus from Croatia. The clinical manifestations elicited by the bite were only local, and included bleeding, pulsatility and paresthesia, followed by sweating and signs of inflammation. The observed features subsided quickly, and the patient recovered fully with no long-term illness. Therefore, we conclude that M. insignitus does not represent a substantial (i.e. life threatening or morbidity-causing) threat. However, as related species in the Malpolon genus are known to be capable to deliver neurotoxic envenoming, we recommend to nevertheless carefully interact with M. insignitus and recommend that future studies should unveil its venom composition.

Global parameter optimisation and sensitivity analysis of antivenom pharmacokinetics and pharmacodynamics

In recent years it has become possible to design snakebite antivenoms with diverse pharmacokinetic properties. Owing to the pharmacokinetic variability of venoms, the choice of antivenom scaffold may influence a treatment's neutralisation coverage. Computation offers a useful medium through which to assess the pharmacokinetics and pharmacodynamics of envenomation-treatment systems, as antivenoms with identical neutralising capacities can be simulated. In this study, we simulate envenomation and treatment with a variety of antivenoms, to define the properties of effective antivenoms. Systemic envenomation and treatment were described using a two-compartment pharmacokinetic model. Treatment of Naja sumatrana and Cryptelytrops purpureomaculatus envenomation was simulated with a set of 200,000 theoretical antivenoms across 10 treatment time delays. These two venoms are well-characterised and have differing pharmacokinetic properties. The theoretical antivenom set varied across molecular weight, dose, kon, koff, and valency. The best and worst treatments were identified using an area under the curve metric, and a global sensitivity analysis was performed to quantify the influence of the input parameters on treatment outcome. The simulations show that scaffolds of diverse molecular formats can be effective. Molecular weight and valency have a negligible direct impact on treatment outcome, however low molecular weight scaffolds offer more flexibility across the other design parameters, particularly when treatment is delayed. The simulations show kon to primarily mediate treatment efficacy, with rates above 105 M-1s-1 required for the most effective treatments. koff has the greatest impact on the performance of less effective scaffolds. While the same scaffold preferences for improved treatment are seen for both model snakes, the parameter bounds for C. purpureomaculatus envenomation are more constrained. This paper establishes a computational framework for the optimisation of antivenom design.

Structural capacity and continuum of snakebite care in the primary health care system in India: a cross-sectional assessment

BACKGROUND

In 2019, the World Health Organization, set a target to halve the burden of snakebite, by 2030, and identified 'health systems strengthening' as a key pillar of action. In India, the country with most snakebite deaths, the Union Government identified (in September 2022) training of health workers as a priority action area. In this policy context, we provide empirical evidence by analysing the most recent nationwide survey data (District Level Household and Facility Survey - 4), to assess structural capacity and continuum of snakebite care in primary health care system in India.

METHODOLOGY

We evaluated structural capacity for snakebite care under six domains: medicines, equipment, infrastructure, human resources, governance and finance, and health management information systems (HMIS). We categorised states (aspirant, performer, front-runner, achiever) based on the proportion of primary health centres (PHC) and community health centres (CHC), attaining highest possible domain score. We assessed continuum of snakebite care, district-wise, under five domains (connectivity to PHC, structural capacity of PHC, referral from PHC to higher facility, structural capacity of CHC, referral from CHC to higher facility) as adequate or not.

RESULTS

No state excelled ( front-runner or achiever) in all six domains of structural capacity in PHCs or CHCs. The broader domains (physical infrastructure, human resources for health, HMIS) were weaker compared to snakebite care medicines in most states/UTs, at both PHC and CHC levels. CHCs faced greater concerns regarding human resources and equipment availability than PHCs in many states. Among PHCs, physical infrastructure and HMIS were aspirational in all 29 assessed states, while medicines, equipment, human resources, and governance and finance were aspirational in 8 (27.6%), 2 (6.9%), 17 (58.6%), and 12 (41.4%) states respectively. For CHCs, physical infrastructure was aspirational in all 30 assessed states/UTs, whereas HMIS, medicines, equipment, human resources, and governance and finance were aspirational in 29 (96.7%), 11 (36.7%), 27 (90%), 26 (86.7%), and 3 (10%) states respectively. No district had adequate continuum of snakebite care in all domains. Except for transport availability from CHC to higher facilities (48% of districts adequate) and transport availability from PHC to higher facilities (11% of districts adequate), fewer than 2% of districts were adequate in all other domains.

CONCLUSION

Comprehensive strengthening of primary health care, across all domains, and throughout the continuum of care, instead of a piece-meal approach towards health systems strengthening, is necessitated to reduce snakebite burden in India, and possibly other high-burden nations with weak health systems. Health facility surveys are necessitated for this purpose.

Harm due to the use of pressure bandage immobilisation in patients bitten by snakes in Australia

BACKGROUND

Pressure bandage immobilisation has remained the recommended first aid treatment for more than 40 years in Australia. However, whilst it is used in most people bitten by a snake, it is often applied poorly, and patients have been envenomed despite good pressure bandage immobilisation. We report two patients who suffered harm from this procedure.

CASE REPORTS

Two men, a 35-year-old and a 44-year-old, were bitten by snakes. Both had a prompt application of pressure bandage immobilisation, and both reported significant pain requiring opioid analgesia whilst being transferred from remote Australia to Cairns Hospital, Queensland. There were substantial delays (9.5 h and 7.5 h) before the pressure bandage immobilisation was released. As a result, both patients developed severe rhabdomyolysis (33,600 U/L and 16,800 U/L [normal < 171 U/L], respectively); there was no evidence of systemic envenoming. The 35-year-old developed a compartment syndrome that required urgent and repeated surgery. The 44-year-old has ongoing foot paraesthesia two years after the bite.

CONCLUSION

With limited good evidence of benefit, and many issues with its use, I recommend that pressure bandage immobilisation as a first aid measure for snakebite in Australia needs to be re-examined.

Physicochemical and immunological effects of adjuvant formulations with snake venom antigens for immunization of horses for antivenom production

Enhancement of antivenom immune responses in horses through adjuvant technology improves antivenom production efficiency, but substantial local reactogenicity associated with some traditional veterinary adjuvants limits their usability. To explore modern adjuvant systems suitable for generating antivenom responses in horses, we first assessed their physicochemical compatibility with Bothrops asper snake venom. Liposome and nanoparticle aluminum adjuvants exhibited changes in particle size and phospholipid content after mixing with venom, whereas squalene emulsion-based adjuvants remained stable. Next, we evaluated serum antibody response magnitude and neutralization capacity in horses immunized with adjuvant-containing Echis ocellatus, Bitis arietans, Naja nigricollis, and Dendroaspis polylepis venom preparations. Whereas all tested adjuvants elicited significant neutralization capacity against the viperid venoms, the greatest antibody responses were generated by a squalene-in-water emulsion, thus representing a promising novel alternative for antivenom production.

Exotic (non-native) snakebite envenomation in Japan: A review of the literature between 2000 and 2022

A limited number of studies have investigated the clinical characteristics of snakebite envenomation by exotic (non-native) snakes in Japan. This study reviewed the literature to determine the status and risk of bites by exotic pet snakes in Japan. We reviewed reports of snakebite due to exotic snakes in Japan published between 2000 and 2022, excluding reports of bites by snakes native to Japan, such as Gloydius blomhoffii, Rhabdophis tigrinus, and Protobothrops flavoviridis. During the study period, 11 exotic snakebites were recorded, involving 11 species. The majority of those bitten (10/11 cases) were male, all cases were hand injuries, and there were no fatalities. The snakes responsible belonged to the Colubridae (4/11 cases), Viperidae (4/11 cases), and Elapidae (3/11 cases) families. Cases of envenomation by G. brevicaudus, Bungarus candidus, and Dendroaspis angusticeps were of particular interest. Ten of the eleven patients developed local cytotoxic signs, and three developed "compartment syndrome," in which the surgeons performed decompressive incisions. Two bites from elapid snakes and one from a viperid snake resulted in respiratory failure. Antivenom was given in two cases. Complications were observed, such as acute kidney injury, rhabdomyolysis, coagulopathy, and residual dysfunction of the affected finger. Emergency rooms should be prepared to manage patients who have been bitten by exotic snakes, even though the number of reported cases is not high in Japan. Initial stabilization of patients is crucial, before a definitive diagnosis is made, as with native snakebite envenomation. Finger bites are reported in most cases, which may result in functional impairment of the fingers. In order to collect more comprehensive patient data in Japan, a reporting system for all snakebite envenomations should be considered.

A retrospective analysis of epidemiology, clinical features of envenomation, and in-patient management of snakebites in a model secondary hospital of Assam, North-east India

Assam, a Northeastern State of India, is inhabited by several venomous snake species causing substantial morbidity and mortality. The data on the epidemiology of snakebites and their management is underreported in this region. Hence, a secondary health-based retrospective study was carried out at Demow Model Hospital, Sivasagar, Assam, to evaluate the clinical and epidemiological profile of snakebite cases reported in this rural hospital and their management. Snakebites occurring between April 2018 to August 2022 were reviewed based on socio-demographic details of the patient, clinical symptoms, and treatment using a standard questionnaire. Out of the 1011 registered snakebite cases, 139 patients (13.7%) counted for venomous bites, among which 92 patients (66.19%) accounted for viper bites (green pit viper and Salazar's pit viper), and 30 patients (21.5%) were bitten by elapid snakes (Indian monocled Cobra, banded krait, and greater/lesser black krait). A maximum number of snakebite cases (80.5%) were reported from the interior rural villages and documented from July to September (51.3%). Elapid snake envenomed patients, except one, were successfully treated with commercial antivenom, neostigmine, and glycopyrrolate. Because commercial polyvalent antivenom against "Big Four" venomous snakes of India showed poor neutralization of pit-vipers envenomation; therefore, pit-viper bite patients were treated with repurposed drugs magnesium sulfate and glycerin compression dressing. Adverse serum reactions were reported only in 3 (11.1%) cases. The preventive measures and facilities adopted at the Demow Model Hospital significantly reduce snakebite death and morbidity; therefore, they can be s practised across various states in India as a prototype.

Envenomation by Vipera aspis in Piedmont (Italy): A report of three cases, including one case with neurological symptoms

This report describes three cases of human envenomation by the asp viper (Vipera aspis) in Piedmont, north-west Italy. A woman was bitten on the ankle while she was hiking and two herpetologists received bites on the hand while they were manipulating the animals. In the first case, the victim presented severe systemic symptoms (abdominal pain, vomiting, diarrhea) that required treatment with two vials of antivenom and hospitalization for one week. In the second case, the patient manifested neurological symptoms (blepharoptosis, ophtalmoplegia); he was treated with antivenom and discharged after five days. In the third case, the patient was bitten by a juvenile viper and showed only local symptoms (edema and bruising). All patients reported prolonged functional impairment after discharge from hospital. Although uncommon, envenomation by Vipera aspis can cause severe consequences that require immediate management and antivenom administration. These cases highlight the importance of obtaining better knowledge of the intraspecific variability of venoms and its clinical significance, as well as of the factors that determine the severity of snakebite injuries.

The concept of Big Four: Road map from snakebite epidemiology to antivenom efficacy

Snake envenomation is a life-threatening disease caused by the injection of venom toxins from the venomous snake bite. Snakebite is often defined as the occupational or domestic hazard mostly affecting the rural population. India experiences a high number of envenoming cases and fatality due to the nation's diversity in inhabiting venomous snakes. The Indian Big Four snakes namely Russell's viper (Daboia russelii), spectacled cobra (Naja naja), common krait (Bungarus caeruleus), and saw-scaled viper (Echis carinatus) are responsible for majority of the snake envenoming cases and death. The demographic characteristics including occupation, stringent snake habitat management, poor healthcare facilities and ignorance of the rural victims are the primary influencers of high mortality. Biogeographic venom variation greatly influences the clinical pathologies of snake envenomation. The current antivenoms against the Big Four snakes are found to be less immunogenic against the venom toxins emphasizing the necessity of alternative approaches for antivenom generation. This review summarizes the burden of snake envenomation in India by the Big Four snakes including the geographic distribution of snake species and biogeographic venom variation. We have provided comprehensive information on snake venom proteomics that has aided the better understanding of venom induced pathological features, summarized the impact of current polyvalent antivenom therapy highlighting the need for potential antivenom treatment for the effective management of snakebites.

A review of 95 pit viper envenomations in Northcentral Florida (2018-2020)

The medical records of 95 pit viper envenomations in client-owned dogs presented to an academic emergency hospital in the Southeastern United States during the period spanning 2018 and 2020 were retrospectively examined. This study's primary objectives were to record the clinical abnormalities and treatment responses associated with envenomation and their relation to outcome. Approximately 80% of the bites involved the head region associated with varying degrees of hemorrhagic lymphedema. Some of the most common additional symptoms observed were; hypotension (10%), cardiac dysrhythmias (17%), and coagulopathy (21%). Treatment in most cases consisted of intravenous fluids, antivenom, and analgesic drugs. Blood products were used as indicated for anemia and persistent bleeding. The average dose of the F('ab')₂ was 1-2 vials. Additional vials (3-22) were administered as needed to counteract persistent or recurrent coagulopathy and hemolysis. Only 3% of the dogs had mild clinical signs of Type 1 hypersensitivity during their treatment period. Antihistamine use at the tertiary hospital was restricted to the three dogs showing signs of a suspected allergic reaction in response to antivenom administration; these patients received diphenhydramine intramuscularly. A glucocorticoid drug was used in only one dog prior to referral but not subsequently. Ninety dogs had a good outcome, while five died. Historically, pit viper envenomation in dogs in the southeastern United States has been a potentially life-threatening problem. Most dogs will survive if treated promptly and appropriately with adequate amounts of intravenous fluids, and antivenom titrated on severity of clinical presentation.

What drives the risk of being bitten by a viper? A fine spatial scale study in western France

Previous studies on viper bites in France have focused on clinical consequences of envenomation, efficacy of antivenom and epidemiology of bites. Herein, we wanted to clarify temporal and spatial patterns in bite incidence using a fine spatial scale (municipality level). We focused on viper bites recorded over the last 10 years in 4 regions of western France. We addressed the determinants of bite occurrence and number of bites considering the following variables: predicted probability of viper presence, species (V. aspis or V. berus), climatic data, tourism function rate, soil transformation and landscape use. 703 bite cases were retained with significant disparities between areas. Bites occurred either during a garden-related activity (339 cases, 51.2%) or during an activity in the countryside (300 cases, 45.3%). The probability of presence of a viper at the municipality level positively influenced the risk of being bitten (multiplied by 3 for a variation in probability of 0.25 from 0.5) but varied between species (lower in V. berus than V. aspis). Artificial land development had a positive effect on bite risks. Finally, a tourism function rate above 50 beds/100 inhabitants was strongly associated with an increase in the risk of occurrence and frequency of bites. Overall, viper bites recorded in our study were concentrated on the south coastline of Pays de la Loire region. The coastal towns are significant areas of tourist attraction and are located close to preserved semi-natural landscapes that provide favorable habitats for vipers. This convergence may favor human/wildlife encounters.

Alarmins and inflammatory aspects related to snakebite envenomation

Snakebite envenoming is characterized by the injection of a mixture of proteins/toxins present in venom following the bite of a venomous snake. The toxins have potent bioactivity capability to impact different aspects of envenomation evolution. The cascade of immune responses initiated by the participation of venom and/or toxins isolated from snake venom can contribute to the systemic and local inflammatory effects observed in victims of envenomation. To understand envenomation, a deeper comprehension of the numerous cells, mediators, and components that comprise the immune system reaction to the venom components is required. Thus, activities related to the immune response are highlighted in this study, including the initial line of defense of the innate immune response as signals for the complicated reaction led by specialized cells.

Performance of the 20 minutes Whole Blood Clotting Test in detection, monitoring and antivenom therapy of West African Carpet viper (Echis romani) envenoming in resource constrained settings in Nigeria

The 20 minutes Whole Blood Clotting Test (20WBCT) was evaluated in 1541 snakebite patients at 3 hospitals in Nigeria. It was useful in detection, monitoring, guiding antivenom therapy and prognostication of coagulopathy, with initial sensitivity of 84.7% (95%CI:82.7-86.5%) and specificity of 64.3% (95%CI:50.4-76.7%) compared to clinical envenoming. It led to correct decisions regarding administration or withholding antivenom in 97.93% of patients. The proportion of carpet viper (Echis romani) envenomed patients who restored clotting rose steadily following effective antivenom therapy. Patients with positive 20WBCT had severer envenoming, required more blood transfusion, had longer hospital stay and derived higher antivenom protection against death from carpet viper. However, there was no association between positive 20WBCT and fatality or complications.

Snakebite in South Africa: A retrospective review May 2015-June 2020

Snakebite envenoming in Sub-Saharan Africa present a significant public health problem. An investigation into how often species responsible for envenomation were correctly identified, as well as which venomous species caused the most frequent and problematic envenomation symptomatology were conducted to establish severity of this problem from a South African context. Descriptive statistics were used to quantitatively describe the variables in snakebite related Telelog call records reported to the Poison Information Helpline of the Western Cape (PIHWC) over a five-year period. A total of 1411 snakebite related calls were received. In 44% of all snakebite calls the bite was inflicted by an unidentified snake specie. The most snakebites occurred during the summer months from December-March. The most bites occurred in males (20-39 years). The incidence of snakebite in South Africa was 2.39 per 100 000 population, with the highest incidence of snakebite in North-West province of South Africa. In sub-Saharan Africa there is a major underestimation of the incidence of snakebite due to under reporting and absence of physical attendance to health care facilities. The PIHWC provides an invaluable service in assisting and in-forming medical personnel and the public on the management of snakebites. Data collected by centers provides a source of information on the prevalence of snakebites and medically important species that research should be aimed towards.

Pre-clinical efficacy of African medicinal plants used in the treatment of snakebite envenoming: A systematic review

The World Health Organization has listed Snakebite Envenoming (SBE) as a priority neglected tropical disease, with a worldwide annual snakebite affecting 5.4 million people and injuring 2.7 million lives. In many parts of rural areas of Africa and Asia, medicinal plants have been used as alternatives to conventional antisnake venom (ASV) due in part to inaccessibility to hospitals. Systemic reviews (SR) of laboratory-based preclinical studies play an essential role in drug discovery. We conducted an SR to evaluate the relationship between interventional medicinal plants and their observed effects on venom-induced experiments. This SR was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The Modified collaborative approach to meta-analysis and review of animal data from experimental studies (CAMARADES) and SYRCLE's risk of bias tools were used to appraise the included studies. Data were searched online in Medline via PubMed, Embase via OVID, and Scopus. Studies reporting in vivo and in vitro pharmacological activities of African medicinal plants/extracts/constituents against venom-induced pathologies were identified and included for screening. Data from the included studies were extracted and synthesized. Ten studies reported statistically significant percentage protection (40-100%) of animals against venom-induced lethality compared with control groups that received no medicinal plant intervention. Sixteen studies reported significant effects (p ≤ 0.05) against venom-induced pathologies compared with the control group; these include hemolytic, histopathologic, necrotic, and anti-enzymatic effects. The plant family Fabaceae has the highest number of studies reporting its efficacy, followed by Annonaceae, Malvaceae, Combretaceae, Sterculiaceae, and Olacaceae. Some African medicinal plants are preclinically effective against venom-induced lethality, hematotoxicity, and cytotoxicity. The evidence was extracted from three in vitro studies, nine in vivo studies, and five studies that combined both in vivo and in vitro models. The effective plants belong to the Fabaceae family, followed by Malvaceae, and Annonaceae.

Neurotoxic respiratory failure absent following Arizona rattlesnake bites

Warnings of neurotoxic respiratory paralysis following envenomation by rattlesnakes (Crotalus sp.) have been included in numerous scholarly publications over the past 60 years, resulting in fear and anxiety in the public and among clinicians. We examine the validity of the widespread belief that rattlesnakes in the arid southwestern United States, and particularly the Mohave Rattlesnake (Crotalus scutulatus), pose a significant risk of medically relevant respiratory weakness and paralysis in humans. A retrospective review of 3440 suspected rattlesnake bites reported to the Arizona Poison and Drug Information Center between 1999 and 2020 produced no evidence of respiratory weakness in a region with three species known to express significant amounts of neurotoxin in their venoms: Crotalus concolor, C. tigris, and the more widely distributed C. scutulatus. A literature review produced numerous warnings regarding respiratory paralysis following envenomation by rattlesnakes in our region that either lacked references or cited sources that did not contain strong supportive data. We found no case reports of neurotoxic respiratory weakness following Arizona rattlesnake bites in the literature and such reports in surrounding states were scant. We conclude that neurotoxic respiratory failure in this region following rattlesnake envenomation is extraordinarily rare. All rattlesnake bites should receive the same consideration and critical care, and warnings about significant risk of respiratory failure are unwarranted, regardless of species involved.

The anti-snake activity of Nectandra angustifolia flavonoids on phospholipase A2: In vitro and in silico evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

Lauraceae family includes Nectandra angustifolia a species widely used in the folk medicine of South America against various maladies. It is commonly used to treat different types of processes like inflammation, pain, and snakebites. Snakes of the Bothrops genus are responsible for about 97% of the ophidic accidents in northeastern Argentina.

AIM OF THE STUDY

To evaluate the anti-snake activity of the phytochemicals present in N. angustifolia extracts, identify the compounds, and evaluate their inhibitory effect on phospholipase A2 (PLA2) with in vitro and in silico assays.

METHODS

Seasonal variations in the alexiteric potential of aqueous, ethanolic and hexanic extracts were evaluated by inhibition of coagulant, haemolytic, and cytotoxic effects of B. diporus venom. The chemical identity of an enriched fraction obtained by bio-guided fractioning was established by UPLC-MS/MS analysis. Molecular docking studies were carried out to investigate the binding mechanisms of the identified compounds to PLA2 enzyme from snake venom.

RESULTS

All the extracts inhibited venom coagulant activity. However, spring ethanolic extract achieved 100% inhibition of haemolytic activity. Bio-guide fractioning led to an enriched fraction (F4) with the highest haemolytic inhibition. Five flavonoids were identified in this fraction; molecular docking and Molecular Dynamics (MD) simulations indicated the binding mechanisms of the identified compounds. The carbohydrates present in some of the compounds had a critical effect on the interaction with PLA2.

CONCLUSION

This study shows, for the first time, which compounds are responsible for the anti-snake activity in Nectandra angustifolia based on in vitro and in silico assays. The results obtained in this work support the traditional use of this species as anti-snake in folk medicine.

Vulnerability to snakebite envenoming and access to healthcare in the Terai region of Nepal: a geospatial analysis

Background

Snakebite envenoming is a neglected tropical disease that mainly affects poor populations in rural areas. In hyperendemic regions, prevention could partially reduce the constant risk, but the population still needs timely access to adequate treatment. In line with WHO's snakebite roadmap, we aim to understand snakebite vulnerability through modelling of risk and access to treatment, and propose plausible solutions to optimise resource allocation.

Methods

We combined snakebite-risk distribution rasters with travel-time accessibility analyses for the Terai region of Nepal, considering three vehicle types, two seasons, two snakebite syndromes, and uncertainty intervals. We proposed localised and generalised optimisation scenarios to improve snakebite treatment coverage for the population, focusing on the neurotoxic syndrome.

Findings

In the Terai, the neurotoxic syndrome is the main factor leading to high snakebite vulnerability. For the most common scenario of season, syndrome, and transport, an estimated 2.07 (15.3%) million rural people fall into the high vulnerability class. This ranges between 0.3 (2.29%) and 6.8 (50.43%) million people when considering the most optimistic and most pessimistic scenarios, respectively. If all health facilities treating snakebite envenoming could optimally treat both syndromes, treatment coverage of the rural population could increase from 65.93% to 93.74%, representing a difference of >3.8 million people.

Interpretation

This study is the first high-resolution analysis of snakebite vulnerability, accounting for uncertainties in both risk and travel speed. The results can help identify populations highly vulnerable to snakebite envenoming, optimise resource allocation, and support WHO's snakebite roadmap efforts.

Funding

Swiss National Science Foundation.

A case series of samar cobra, Naja samarensis Peters, 1861 (Elapidae) envenomation

The Samar cobra, Naja samarensis Peters, 1861 is one of the World Health Organization's category I venomous snakes in the Philippines. Although N. samarensis is known to inhabit Eastern Visayas, unlike N. philippinensis in Luzon, no clinical case reports have yet been published in the international literature. No immuno-diagnostic assays have been developed for venomous snakes in the Philippines, even for research purposes. Therefore, identification of the causative snake in hospitals is challenging. In vivo pre-clinical tests using mice showed that locally-produced antivenom raised against N. philippinensis venom ["Purified Cobra Antivenom (PCAV)"] cross-neutralised N. samarensis venom. Here, we present five snakebite envenomation cases where causative snakes were confirmed in photos as N. samarensis by an expert local herpetologist. Patients' symptoms and signs varied, from mild to extensive local cytotoxic to systemic neurotoxic envenomation. In one case, venom had been spat into the eye. Out of five patients, two underwent surgical debridement of necrotic tissue at the bite site. One paediatric patient was intubated because of cardiopulmonary arrest. Except for the spitting cobra case, four cases were successfully treated with PCAV and supportive management. These are the first clinical case reports of confirmed N. samarensis envenomation.

Evaluation of the properties of Bungarus caeruleus venom and checking the efficacy of antivenom used in Bangladesh for its bite treatment

As a disaster-prone country with unique geographical features, snake biting is a major public health concern in Bangladesh. The primary reasons of mortality from snakebite include late presentation to the hospital, low efficacy of antivenom, and a lack of adequate management facilities. Because snake venom characteristics vary depending on geographical location, antivenom should be manufactured from snakes native to the region in which it would be administered. Bungarus caeruleus is a highly venomous snake contributing to the major snakebite issue in Bangladesh. Therefore, the neutralization efficacy of the antivenom against B. caeruleus venom was evaluated in the current study along with the characterization of venom. For biological characterization of venom, RP-HPLC and SDS-PAGE profiling, hemolytic activity, hemorrhagic activity, phospholipases A₂ (PLA₂) activity, edema inducing activity and histopathological observations were carried out following standard protocol. LD₅₀ of the venom was calculated along with neutralization potency of Incepta antivenom through probit analysis. Results showed that venom possesses phospholipase A₂ activity, hemolytic activity and edema inducing activity while hemorrhagic activity was absent in the skin of envenomed mice. Histopathological alterations including necrosis, congestion and infiltrations were observed in envenomed mice organs after hematoxylin and eosin staining. Neutralization study showed that Incepta polyvalent antivenom could neutralize (potency 0.53 mg/ml) the lethal effect in in vitro study on mice. Further investigation on snakebite epidemiology and clinical observations of the envenomed patients will help in combating the snakebite problem more efficiently.