Low-dose adrenaline, promethazine, and hydrocortisone in the prevention of acute adverse reactions to antivenom following snakebite: a randomised, double-blind, placebo-controlled trial

The Role of Snake Venom Proteins in Inducing Inflammation Post-Envenomation: An Overview on Mechanistic Insights and Treatment Strategies

The intricate combination of organic and inorganic compounds found in snake venom includes proteins, peptides, lipids, carbohydrates, nucleotides, and metal ions. These components work together to immobilise and consume prey through processes such as paralysis and hypotension. Proteins, both enzymatic and non-enzymatic, form the primary components of the venom. Based on the effects they produce, venom can be classified as neurotoxic, hemotoxic, and cytotoxic. Studies have shown that, after envenomation, proteins in snake venom also contribute significantly to the induction of inflammatory responses which can either have systemic or localized consequences. This review delves into the mechanisms by which snake venom proteins trigger inflammatory responses, focusing on key families such as phospholipase A2, metalloproteinases, serine proteases, C-type lectins, cysteine-rich secretory proteins, and L-amino acid oxidase. In addition, the role of venom proteins in activating various inflammatory pathways, including the complement system, inflammasomes, and sterile inflammation are also summarized. The available therapeutic options are examined, with a focus on antivenom therapy and its side effects. In general, this review offers a comprehensive understanding of the inflammatory mechanisms that are triggered by snake venom proteins and the side effects of antivenom treatment. All these emphasize the need for effective strategies to mitigate these detrimental effects.

Acute compartment syndrome leading to fasciotomy, severe morbidity and long-term disabilities following Sri Lankan Green pit viper (Peltopelor trigonocephalus) envenomation

Green pit viper (Peltopelor trigonocephalus) is a medically important endemic snake in Sri Lanka. Its envenoming commonly causes local effects such as pain, swelling, blistering, and lymphadenopathy and rarely causes venom-induced consumption coagulopathy as a systemic effect. Despite its frequent encounters in estates, commonly tea and cinnamon plantations, reports of envenoming are rare and limited to nine reports in the literature. An extensive literature review confirms no previous reports of compartment syndrome following Sri Lankan Green pit viper bites. We report two cases of acute compartment syndrome leading to fasciotomy, of which, in addition, case 1 patient developed venom-induced consumption coagulopathy.

A case of Western Gaboon viper (Bitis rhinoceros) envenomation: Successful treatment with South African Institute for Medical Research (SAIMR) antivenom after North American crotalid antivenom failure

We report a case of Western Gaboon viper (Bitis rhinoceros) envenomation in which the patient's symptoms progressed despite treatment with North American crotalid antivenom but improved after receiving South African Institute for Medical Research (SAIMR) polyvalent antivenom. A 59-year-old man was hospitalized after reportedly being bitten by a Gaboon viper (Bitis gabonica). On arrival, he had normal vital signs, two puncture wounds on his left hand, and edema distal to the wrist. The hospital contacted the local poison center who conveyed that crotalid antivenom would be ineffective and recommended transfer to a snakebite center for species-appropriate antivenom. However, this recommendation was disregarded. Initial laboratory tests 2 hours after envenomation revealed a platelet count of 77 x 109/L; other parameters were normal. He received six vials of crotalid antivenom (CroFab®) followed by three maintenance doses (total 12 vials). The next morning, swelling had progressed proximal to the elbow and platelets decreased to 37 x 109/L. He was subsequently transferred and received SAIMR polyvalent antivenom. Six hours later, his platelets were 130 x 109/L. The next morning, his swelling had significantly improved. He was discharged the following day. After discharge, it was discovered that the snake was a Bitis rhinoceros. Bitis gabonica and Bitis rhinoceros are popular captive snakes in the United States. Bitis rhinoceros was formerly a sub-species of B. gabonica, and they are often referred to interchangeably. Their venoms cause tissue edema, coagulopathy, and in severe cases, hemorrhage, dysrhythmias, and death. Antivenom is not widely available in the United States often necessitating patient transfer or antivenom delivery. This case addresses the question of whether crotalid antivenom, which is ubiquitous in the United States, can treat B. gabonica and B. rhinoceros envenomations and highlights the need for consultation with a poison center to facilitate administration of species-appropriate antivenom.

A Nationwide Study on the Risks of Complications and Healthcare Costs of Snakebite Envenomation in Taiwan

In Taiwan, six medically important venomous snakes, Trimeresurus stejnegeri stejnegeri, Protobothrops mucrosquamatus, Deinagkistrodon acutus, Daboia siamensis, Naja atra, and Bungarus multicinctus, are found. However, comprehensive research on the complications and associated healthcare costs of snakebite envenomation (SBE) is lacking. We retrospectively analyzed pertinent information from the Taiwan National Health Insurance Research Database dated January 2002 to December 2014. We investigated the risk factors for complications and their impact on healthcare costs. Among the 12,542 patients with SBE, those from N. atra or B. multicinctus were more likely to experience wound infections and neurological complications than were those from T. s. stejnegeri or P. mucrosquamatus. In addition, being female, being elderly, and having a Charlson Comorbidity Index equal to or greater than 3 points were associated with an increased likelihood of wound infections and psychological complications. The annual national economic burden averaged US$1,083,624, with an average healthcare cost of US$1,129 per SBE. Snakebite envenomations from N. atra or B. multicinctus, as well as various complications, resulted in significantly higher costs. It is crucial to comprehend the risk factors for complications and their role in increasing expenses to provide insight for tailored healthcare interventions, mitigate complications, and reduce the economic burdens associated with SBEs.

The Chinese guideline for management of snakebites

In 2009, the World Health Organization included snakebite on the list of neglected tropical diseases, acknowledging it as a common occupational hazard for farmers, plantation workers, and others, causing tens of thousands of deaths and chronic physical disabilities every year. This guideline aims to provide practical information to help clinical professionals evaluate and treat snakebite victims. These recommendations are based on clinical experience and clinical research evidence. This guideline focuses on the following topics: snake venom, clinical manifestations, auxiliary examination, diagnosis, treatments, and prevention.

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.

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.

Managing anaphylaxis: Epinephrine, antihistamines, and corticosteroids: More than 10 years of Cross-Canada Anaphylaxis REgistry data

BACKGROUND

Epinephrine is the first-line treatment for anaphylaxis but is often replaced with antihistamines or corticosteroids. Delayed epinephrine administration is a risk factor for fatal anaphylaxis. Convincing data on the role of antihistamines and corticosteroids in anaphylaxis management are sparse.

OBJECTIVE

To establish the impact of prehospital treatment with epinephrine, antihistamines, and/or corticosteroids on anaphylaxis management.

METHODS

Patients presenting with anaphylaxis were recruited prospectively and retrospectively in 10 Canadian and 1 Israeli emergency departments (EDs) between April 2011 and August 2022, as part of the Cross-Canada Anaphylaxis REgistry. Data on anaphylaxis cases were collected using a standardized form. Primary outcomes were uncontrolled reactions (>2 doses of epinephrine in ED), no prehospital epinephrine use, use of intravenous fluids in ED, and hospital admission. Multivariate regression was used to identify factors associated with primary outcomes.

RESULTS

Among 5364 reactions recorded, median age was 8.8 years (IQR, 3.78-16.9); 54.9% of the patients were males, and 52.5% had a known food allergy. In the prehospital setting, 37.9% received epinephrine; 44.3% received antihistamines, and 3.15% received corticosteroids. Uncontrolled reactions happened in 250 reactions. Patients treated with prehospital epinephrine were less likely to have uncontrolled reactions (adjusted odds ratio [aOR], 0.955 [95% CI, 0.943-0.967]), receive intravenous fluids in ED (aOR, 0.976 [95% CI, 0.959-0.992]), and to be admitted after the reaction (aOR, 0.964 [95% CI, 0.949-0.980]). Patients treated with prehospital antihistamines were less likely to have uncontrolled reactions (aOR, 0.978 [95% CI, 0.967-0.989]) and to be admitted after the reaction (aOR, 0.963 [95% CI, 0.949-0.977]). Patients who received prehospital corticosteroids were more likely to require intravenous fluids in ED (aOR, 1.059 [95% CI, 1.013-1.107]) and be admitted (aOR, 1.232 [95% CI, 1.181-1.286]).

CONCLUSION

Our findings in this predominantly pediatric population support the early use of epinephrine and suggest a beneficial effect of antihistamines. Corticosteroid use in anaphylaxis should be revisited.

Incidence of serum sickness following Indian polyvalent antivenom therapy in a cohort of snake-envenomed patients in rural Sri Lanka

INTRODUCTION

Serum sickness is a poorly reported delayed adverse reaction following snake antivenom therapy. We aimed to assess the frequency of serum sickness associated with administering Indian polyvalent antivenom in Sri Lanka.

METHODS

We recruited patients from the Anuradhapura snakebite cohort who were admitted to a rural tertiary care hospital in Sri Lanka over one year period. Patients were interviewed over the phone 21 to 28 days post-envenoming to collect data on clinical effects: fever/chills, arthralgia/myalgia, rash, malaise, headache, abdominal pain, and nausea/vomiting. The presence of three or more symptoms between the 5th to 20th days after snake envenoming was defined as serum sickness.

RESULTS

We were able to contact 98/122 (80%) patients who received antivenom and 423/588 (72%) who did not receive antivenom during the study period. The treated patients received a median dose of 20 vials (interquartile range: 20-30) of Indian polyvalent antivenom and of them, 92 (92%) received premedication. However, 67/98 (68%) developed acute adverse reactions to antivenom, including 19/98 (19%) developing anaphylaxis. Only 4/98 (4%) who received antivenom met the criteria for serum sickness, compared to none who did not receive antivenom therapy. All patients who developed serum sickness were envenomed by Russell's vipers, were premedicated, and received VINS Bioproducts antivenom. Three of them were treated with hydrocortisone in the acute stage, as premedication or as a treatment for acute adverse reactions of antivenom. Although all four patients sought medical advice for their symptoms, only one was clinically suspected to be serum sickness and treated, while the others were treated for infections.

CONCLUSIONS

We confirmed that Indian polyvalent antivenom use in Sri Lanka is associated with high rates of acute adverse reactions. In contrast to studies of other antivenoms only a small proportion of patients developed serum sickness.

A case of envenoming by a Persian false-horned viper Pseudocerastes persicus (Duméril, Bibron & Duméril, 1854) (Serpentes: Viperidae) in Southeastern Iran

Despite the wide distribution of the Persian false-horned viper (Pseudocerastes persicus) in the Middle East, few identified bites have been reported. A 33-year-old herpetologist bitten on the hand by Pseudocerastes persicus in Kerman Province, Southeastern Iran, developed local pain and extensive swelling with mild non-specific systemic symptoms and minimal laboratory evidence of systemic envenoming.

Kounis syndrome following an anaphylactic reaction to antivenom in a patient with Russell's viper (Daboia russelii) bite: A case report

Kounis syndrome is the occurrence of acute coronary syndrome associated with mast cell and platelet activation in the setting of allergic or anaphylactic insults. Kounis syndrome has been previously reported following snake envenoming rarely, with or without antivenom therapy. We report a case of inferolateral ST elevation myocardial infarction 32 hours from a confirmed Russell's viper bite. He also had an anaphylactic reaction soon after antivenom. The absence of underlying atheromatous coronary artery disease during subsequent cardiac imaging was suggestive of a diagnosis of a type I variant of Kounis syndrome. Chest pain completely resolved by day 6 following initiation of standard treatment for acute coronary syndrome. Concurrence of allergic features and acute coronary syndrome in a snakebite patient following antivenom therapy should alert clinicians to the possibility of Kounis syndrome, which should be diagnosed with a high degree of clinical suspicion.

Early Adverse Reactions to Snake Antivenom: Poison Center Data Analysis

Antivenom is an essential treatment for snake envenomation; however, early adverse reactions (EARs) are major limitations to its use. We performed a retrospective cross-sectional study using Ramathibodi Poison Center data (January 2016 to December 2017) to clarify the incidence and severity of EARs following different F(ab’)2 antivenoms. Among 1006 envenomed patients, 684 (68%) received antivenom therapy with a total of 1157 doses, mostly green pit viper antivenom. The overall EAR incidence and rate were 22. 5% (154/684) and 15% (173/1157), respectively. The EAR rate following each type of antivenom was >10%, except for Russell’s viper antivenom (2.9%); the severe reaction rate was 2.6% (30/1157). Malayan pit viper bites caused a high incidence of EARs (37.8%) and the highest EAR rate (22.3%). Fifty-two cases developed anaphylaxis. All EARs occurred within 2 h after treatment initiation. No deaths were attributed to EARs. The duration of administration was significantly different between doses of antivenom that induced EARs and those that did not. In conclusion, all types and every dose of antivenom should be infused for 30−60 min. Preparation of resuscitation equipment and continuous clinical observation are crucial for at least 2 h after administration, and prompt treatment should be provided when EARs occur.

A retrospective study of antivenom-associated adverse reaction and anaphylaxis at Ngwelezana Hospital, South Africa

BACKGROUND

Snakebite victims are commonly seen in KwaZulu-Natal Hospitals, with only a minority of patients requiring antivenom. This study reviewed antivenom-associated adverse events at our institution, after administration of the South African Vaccine Producers (SAVP) polyvalent antivenom.

METHODS

A retrospective review, over 52 months (January 2016-April 2020), of patients who received antivenom. Demographics, clinical details and clinical course following antivenom administration were analysed.

RESULTS

Emergency department doctors treated 758 snakebites; 156 patients were admitted of which 51 (33%) received antivenom. Indications for antivenom included: neurotoxicity (24%), haemotoxicity (18%) and significant cytotoxicity (58%). Antivenom-associated adverse events occurred in 61% of patients; with 47% developing anaphylaxis requiring adrenaline infusion. There was a higher incidence of anaphylaxis in children (57%) than in adults (40%), p = 0.55. There was no association between antivenom dose and anaphylaxis. No benefit was noted with adrenaline premedication (p = 0.64), nor with the addition of antihistamine or steroid pre-medicants to adrenaline (p = 0.61). Multivariable logistic regression identified age as a predictor for anaphylaxis, but not dose or duration of antivenom and not any particular form of premedication. Intubation was required in 29% of patients developing anaphylaxis. There were no deaths and all patients made full recovery.

CONCLUSION

Almost half of the patients at Ngwelezana hospital in Kwazulu-Natal receiving the SAVP polyvalent antivenom developed anaphylaxis requiring adrenaline infusion, with children at higher risk. The administration of this antivenom must only be given for valid indications, in a high-care environment by medical personnel ready to manage anaphylactic shock. The addition of antihistamine and corticosteroids to adrenaline for premedication has no added benefit.

Exploring the Utility of ssDNA Aptamers Directed against Snake Venom Toxins as New Therapeutics for Snakebite Envenoming

Snakebite is a neglected tropical disease that causes considerable death and disability in the tropical world. Although snakebite can cause a variety of pathologies in victims, haemotoxic effects are particularly common and are typically characterised by haemorrhage and/or venom-induced consumption coagulopathy. Antivenoms are the mainstay therapy for treating the toxic effects of snakebite, but despite saving thousands of lives annually, these therapies are associated with limited cross-snake species efficacy due to venom variation, which ultimately restricts their therapeutic utility to particular geographical regions. In this study, we sought to explore the potential of ssDNA aptamers as toxin-specific inhibitory alternatives to antibodies. As a proof of principle model, we selected snake venom serine protease toxins, which are responsible for contributing to venom-induced coagulopathy following snakebite envenoming, as our target. Using SELEX technology, we selected ssDNA aptamers against recombinantly expressed versions of the fibrinogenolytic SVSPs ancrod from the venom of C. rhodostoma and batroxobin from B. atrox. From the resulting pool of specific ssDNA aptamers directed against each target, we identified candidates that exhibited low nanomolar binding affinities to their targets. Downstream aptamer-linked immobilised sorbent assay, fibrinogenolysis, and coagulation profiling experiments demonstrated that the candidate aptamers were able to recognise native and recombinant SVSP toxins and inhibit the toxin- and venom-induced prolongation of plasma clotting times and the consumption of fibrinogen, with inhibitory potencies highly comparable to commercial polyvalent antivenoms. Our findings demonstrate that rationally selected toxin-specific aptamers can exhibit broad in vitro cross-reactivity against toxin isoforms found in different snake venoms and are capable of inhibiting toxins in pathologically relevant in vitro and ex vivo models of venom activity. These data highlight the potential utility of ssDNA aptamers as novel toxin-inhibiting therapeutics of value for tackling snakebite envenoming.

Exploring the Utility of Recombinant Snake Venom Serine Protease Toxins as Immunogens for Generating Experimental Snakebite Antivenoms

Snakebite is a neglected tropical disease that causes high rates of global mortality and morbidity. Although snakebite can cause a variety of pathologies in victims, haemotoxic effects are particularly common and are typically characterised by haemorrhage and/or venom-induced consumption coagulopathy. Despite polyclonal antibody-based antivenoms being the mainstay life-saving therapy for snakebite, they are associated with limited cross-snake species efficacy, as there is often extensive toxin variation between snake venoms, including those used as immunogens for antivenom production. This restricts the therapeutic utility of any antivenom to certain geographical regions. In this study, we explored the feasibility of using recombinantly expressed toxins as immunogens to stimulate focused, pathology-specific, antibodies in order to broadly counteract specific toxins associated with snakebite envenoming. Three snake venom serine proteases (SVSP) toxins, sourced from geographically diverse and medically important viper snake venoms, were successfully expressed in HEK293F mammalian cells and used for murine immunisation. Analyses of the resulting antibody responses revealed that ancrod and RVV-V stimulated the strongest immune responses, and that experimental antivenoms directed against these recombinant SVSP toxins, and a mixture of the three different immunogens, extensively recognised and exhibited immunological binding towards a variety of native snake venoms. While the experimental antivenoms showed some reduction in abnormal clotting parameters stimulated by the toxin immunogens and crude venom, specifically reducing the depletion of fibrinogen levels and prolongation of prothrombin times, fibrinogen degradation experiments revealed that they broadly protected against venom- and toxin-induced fibrinogenolytic functional activities. Overall, our findings further strengthen the case for the use of recombinant venom toxins as supplemental immunogens to stimulate focused and desirable antibody responses capable of neutralising venom-induced pathological effects, and therefore potentially circumventing some of the limitations associated with current snakebite therapies.

Outcomes in intervention research on snakebite envenomation: a systematic review

INTRODUCTION

A core outcome set (COS) is a minimal list of consensus outcomes that should be used in all intervention research in a specific domain. COS enhance the ability to undertake meaningful comparisons and to understand the benefits or harms of different treatments. A first step in developing a COS is to identify outcomes that have been used previously. We did this global systematic review to provide the foundation for development of a region-specific COS for snakebite envenomation.  Methods: We searched 15 electronic databases, eight trial registries, and reference lists of included studies to identify reports of relevant trials, protocols, registry records and systematic reviews. We extracted verbatim data on outcomes, their definitions, measures, and time-points. Outcomes were classified as per an existing outcome taxonomy, and we identified unique outcomes based on similarities in the definition and measurement of the verbatim outcomes.

RESULTS

We included 107 records for 97 studies which met our inclusion criteria. These reported 538 outcomes, with a wide variety of outcome measures, definitions, and time points for measurement. We consolidated these into 88 unique outcomes, which we classified into core areas of mortality (1, 1.14 %), life impact (6, 6.82%), resource use (15, 17.05%), adverse events (7, 7.95%), physiological/clinical (51, 57.95%), and composite (8, 9.09%) outcomes. The types of outcomes varied by the type of intervention, and by geographic region. Only 15 of the 97 trials (17.04%) listed Patient Related Outcome Measures (PROMS).

CONCLUSION

Trials evaluating interventions for snakebite demonstrate heterogeneity on outcomes and often omit important information related to outcome measurement (definitions, instruments, and time points). Developing high quality, region-specific COS for snakebite could inform the design of future trials and improve outcome reporting. Measurement of PROMS, resource use and life impact outcomes in trials on snakebite remains a gap.

Synthetic antibodies block receptor binding and current-inhibiting effects of α-cobratoxin from Naja kaouthia

Each year, thousands of people fall victim to envenomings caused by cobras. These incidents often result in death due to paralysis caused by α-neurotoxins from the three-finger toxin (3FTx) family, which are abundant in elapid venoms. Due to their small size, 3FTxs are among the snake toxins that are most poorly neutralized by current antivenoms, which are based on polyclonal antibodies of equine or ovine origin. While antivenoms have saved countless lives since their development in the late 18th century, an opportunity now exists to improve snakebite envenoming therapy via the application of new biotechnological methods, particularly by developing monoclonal antibodies against poorly neutralized α-neurotoxins. Here, we describe the use of phage-displayed synthetic antibody libraries and the development and characterization of six synthetic antibodies built on a human IgG framework and developed against α-cobratoxin - the most abundant long-chain α-neurotoxin from Naja kaouthia venom. The synthetic antibodies exhibited sub-nanomolar affinities to α-cobratoxin and neutralized the curare-mimetic effect of the toxin in vitro. These results demonstrate that phage display technology based on synthetic repertoires can be used to rapidly develop human antibodies with drug-grade potencies as inhibitors of venom toxins.

Hydrocortisone for Preventing Adverse Drug Reactions to Snake Antivenom: A Meta-Analysis

Objective

Pretreatment with hydrocortisone (prehydrocortisone) has been used to protect against adverse drug reactions (ADRs) following antivenom administration after snakebite. However, controversial results have been reported in studies evaluating its efficacy. Herein, we conducted a meta-analysis to evaluate the effect of prehydrocortisone on the risk of ADRs.

Methods

We conducted a systematic search of PubMed, Embase, and Cochrane for relevant studies on the literature published up to December 6, 2020, with no language restrictions. Premedications, including hydrocortisone with or without other drugs, were compared with placebo or no premedication. Our primary end point was the risk of ADRs, which was reported as the number of patients who developed ADRs divided by the total number of snakebite patients administered with antivenom separately for the prehydrocortisone and control groups for each study. We evaluated pooled data using of a random-effects model.

Results

Among 831 identified studies, 4 were eligible and included in our analysis (N = 1348 participants). Upon combining all eight comparisons from the four selected studies, the overall pooled odds ratio (OR) for ADRs was 0.47 (95% CI 0.19, 1.17; p=0.11; I² = 68%). When the analysis was restricted to only articles using hydrocortisone with other drugs, the pooled OR was 0.19 (95% CI 0.05, 0.75; p=0.02; I² = 55%). The result was not statistically significant when the analysis was restricted to studies using prehydrocortisone alone, or randomized controlled designs, or cohorts. Our study was limited by heterogeneity, quality, and a paucity of data.

Conclusions

The findings in this study revealed that prehydrocortisone alone was ineffective. However, the substantial beneficial effect of prehydrocortisone combinations with premedications (injectable antihistamines or adrenaline) used against ADRs cannot be excluded. Therefore, the use of prehydrocortisone combinations with premedications (injectable antihistamines or adrenaline) as a prophylaxis may reduce the ADRs to antivenom.

A Clinical Practice Guideline for the Emergency Management of Anaphylaxis (2020)

Background: For anaphylaxis, a life-threatening allergic reaction, the incidence rate was presented to have increased from the beginning of the 21st century. Underdiagnosis and undertreatment of anaphylaxis are public health concerns. Objective: This guideline aimed to provide high-quality and evidence-based recommendations for the emergency management of anaphylaxis. Method: The panel of health professionals from fifteen medical areas selected twenty-five clinical questions and formulated the recommendations with the supervision of four methodologists. We collected evidence by conducting systematic literature retrieval and using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. Results: This guideline made twenty-five recommendations that covered the diagnosis, preparation, emergency treatment, and post-emergency management of anaphylaxis. We recommended the use of a set of adapted diagnostic criteria from the American National Institute of Allergy and Infectious Diseases and the Food Allergy and Anaphylaxis Network (NIAID/FAAN), and developed a severity grading system that classified anaphylaxis into four grades. We recommended epinephrine as the first-line treatment, with specific doses and routes of administration for different severity of anaphylaxis or different conditions. Proper dosage is critical in the administration of epinephrine, and the monitor is important in the IV administration. Though there was only very low or low-quality evidence supported the use of glucocorticoids and H1 antagonists, we still weakly recommended them as second-line medications. We could not make a well-directed recommendation regarding premedication for preventing anaphylaxis since it is difficult to weigh the concerns and potential effects. Conclusion: For the emergency management of anaphylaxis we conclude that: • NIAID/FAAN diagnostic criteria and the four-tier grading system should be used for the diagnosis • Prompt and proper administration of epinephrine is critical.

TRUE-1: Trial of Repurposed Unithiol for snakebite Envenoming phase 1 (safety, tolerability, pharmacokinetics and pharmacodynamics in healthy Kenyan adults)

Background: Snakebites affect over 5 million people each year, and over 100,000 per year die as a result. The only available treatment is antivenom, which has many shortcomings including high cost, intravenous administration, and high risk of adverse events. One of the most abundant and harmful components of viper venoms are the zinc-dependent snake venom metalloproteinases (SVMPs). Unithiol is a chelating agent which is routinely used to treat heavy metal poisoning. In vivo experiments in small animal models have demonstrated that unithiol can prevent local tissue damage and death caused by a certain viper species. This phase I clinical trial will assess the safety of ascending doses of unithiol with a view for repurposing for snakebite indication. Methods: This open label, single agent, phase I clinical trial of a repurposed drug has a primary objective to evaluate the safety of escalating doses of unithiol, and a secondary objective to describe its pharmacokinetics. In total, 64 healthy Kenyan volunteers from Kilifi County will be dosed in consecutive groups of eight, with dose escalation decisions dependent on review of safety data by an independent data safety monitoring board. Four groups will receive ascending single oral doses, two will receive multiple oral doses, and two will receive single intravenous doses. Follow-up will be for 6-months and includes full adverse event reporting. Pharmacokinetic analysis will define the Cmax, Tmax, half-life and renal elimination. Conclusions: This clinical trial will assess the safety and tolerability of a promising oral therapeutic in a relevant setting where snakebites are prevalent. Unithiol is likely to be safer than antivenom, is easier to manufacture, has activity against diverse snake species, and can be administered orally, and thus shows promise for repurposing for tropical snakebite. Pan African Clinical Trials Registry: PACTR202103718625048 (3/3/2021).

EAACI guidelines: Anaphylaxis (2021 update)

Anaphylaxis is a clinical emergency which all healthcare professionals need to be able to recognize and manage. The European Academy of Allergy and Clinical Immunology Anaphylaxis multidisciplinary Task Force has updated the 2014 guideline. The guideline was developed using the AGREE II framework and the GRADE approach. The evidence was systematically reviewed and recommendations were created by weighing up benefits and harms. The guideline was peer-reviewed by external experts and reviewed in a public consultation. The use of clinical criteria to identify anaphylaxis is suggested with blood sampling for the later measurement of tryptase. The prompt use of intramuscular adrenaline as first-line management is recommended with the availability of adrenaline autoinjectors to patients in the community. Pharmacokinetic data should be provided for adrenaline autoinjector devices. Structured, comprehensive training for people at risk of anaphylaxis is recommended. Simulation training and visual prompts for healthcare professionals are suggested to improve the management of anaphylaxis. It is suggested that school policies reflect anaphylaxis guidelines. The evidence for the management of anaphylaxis remains mostly at a very low level. There is an urgent need to prioritize clinical trials with the potential to improve the management of patients at risk of anaphylaxis.

Antivenom: An immunotherapy for the treatment of snakebite envenoming in sub-Saharan Africa

Snakebite envenoming (SBE) leads to significant morbidity and mortality, resulting in over 90,000 deaths and approximately 400,000 amputations annually. In sub-Saharan Africa (SSA) alone, SBE accounts for over 30,000 deaths per annum. Since 2017, SBE has been classified as a priority Neglected Tropical Disease (NTD) by the World Health Organisation (WHO). The major species responsible for mortality from SBE within SSA are from the Bitis, Dendroaspis, Echis and Naja genera. Pharmacologically active toxins such as metalloproteinases, serine proteinases, 3-finger toxins, kunitz-type toxins, and phospholipase A₂s are the primary snake venom components. These toxins induce cytotoxicity, coagulopathy, hemorrhage, and neurotoxicity in envenomed victims. Antivenom is currently the only available venom-specific treatment for SBE and contains purified equine or ovine polyclonal antibodies, collected from donor animals repeatedly immunized with low doses of adjuvanted venom. The resulting plasma or serum contains a high titre of specific antibodies, which can then be collected and stored until required. The purified antibodies are either whole IgG, monovalent fragment antibody (Fab) or divalent fragment antibody F(ab')₂. Despite pharmacokinetic and pharmacodynamic differences, all three are effective in the treatment of SBE. No antivenom is without adverse reactions but, the level of their impact and severity varies from benign early adverse reactions to the rarely occurring fatal anaphylactic shock. However, the major side effects are largely reversible with immediate administration of adrenaline and corticosteroids. There are 16 different antivenoms marketed within SSA, but the efficacy and safety profiles are only published for less than 50% of these products.

Clinical management of snakebite envenoming: Future perspectives

Snakebite envenoming is a major cause of morbidity and mortality in rural communities throughout the tropics. Generally, the main clinical features of snakebites are local swelling, tissue necrosis, shock, spontaneous systemic hemorrhage, incoagulable blood, paralysis, rhabdomyolysis, and acute kidney injury. These clinical manifestations result from complex biochemical venom constituents comprising of cytotoxins, hemotoxins, neurotoxins, myotoxins, and other substances. Timely diagnosis of envenoming and identification of the responsible snake species is clinically challenging in many parts of the world and necessitates prompt and thorough clinical assessment, which could be supported by the development of reliable, affordable, widely-accessible, point-of-care tests. Conventional antivenoms based on polyclonal antibodies derived from animals remain the mainstay of therapy along with supportive medical and surgical care. However, while antivenoms save countless lives, they are associated with adverse reactions, limited potency, and are relatively inefficacious against presynaptic neurotoxicity and in preventing necrosis. Nevertheless, major scientific and technological advances are facilitating the development of new molecular and immunologic diagnostic tests, as well as a new generation of antivenoms comprising human monoclonal antibodies with broader and more potent neutralization capacity and less immunogenicity. Repurposed pharmaceuticals based on small molecule inhibitors (e.g., marimastat and varespladib) used alone and in combination against enzymatic toxins, such as metalloproteases and phospholipase A2s, have shown promise in animal studies. These orally bioavailable molecules could serve as early interventions in the out-of-hospital setting if confirmed to be safe and efficacious in clinical studies. Antivenom access can be improved by the usage of drones and ensuring constant antivenom supply in remote endemic rural areas. Overall, the improvement of clinical management of snakebite envenoming requires sustained, coordinated, and multifaceted efforts involving basic and applied sciences, new technology, product development, effective clinical training, implementation of existing guidelines and therapeutic approaches, supported by improved supply of existing antivenoms.

Control of snakebite envenoming: A mathematical modeling study

A mathematical model is designed to assess the impact of some interventional strategies for curtailing the burden of snakebite envenoming in a community. The model is fitted with real data set. Numerical simulations have shown that public health awareness of the susceptible individuals on snakebite preventive measures could reduce the number of envenoming and prevent deaths and disabilities in the population. The simulations further revealed that if at least fifty percent of snakebite envenoming patients receive early treatment with antivenom a substantial number of deaths will be averted. Furthermore, it is shown using optimal control that combining public health awareness and antivenom treatment averts the highest number of snakebite induced deaths and disability adjusted life years in the study area. To choose the best strategy amidst limited resources in the study area, cost effectiveness analysis in terms of incremental cost effectiveness ratio is performed. It has been established that the control efforts of combining public health awareness of the susceptible individuals and antivenom treatment for victims of snakebite envenoming is the most cost effective strategy. Approximately the sum of US$72,548 is needed to avert 117 deaths or 2,739 disability adjusted life years that are recorded within 21 months in the study area. Thus, the combination of these two control strategies is recommended.

Snakebite envenoming (SBE) is currently one of the life-threatening neglected diseases especially in developing countries. The fight against this menace requires multidisciplinary approach. Owing to significant number of deaths and disabilities recorded per year in West African savanna region, we developed a new mathematical model for SBE in order to gain more insights into the dynamics and control of SBE. It is clear that communities in northeast Nigeria do not have adequate health information on self-protection against SBE and the antivenom is almost scarce and unaffordable. Thus, we evaluated the cost-effectiveness and potential impact of both public health awareness campaign and treatment for SBE as interventional strategies against snakebite. We discovered that public health awareness is crucial in averting SBE, deaths and disabilities. Also, if at least 50% of SBE victims received treatment within 24 hours of bite, a significant number of deaths and disabilities will be prevented. Furthermore, the study revealed that the combination of public health awareness and treatment decreases the burden of the disease in terms of deaths and disability adjusted life years at a lesser cost as compared with implementing one of these interventions separately. These results can be used as a guide for planning SBE control policy in northeast Nigeria and beyond.

Pathology-specific experimental antivenoms for haemotoxic snakebite: The impact of immunogen diversity on the in vitro cross-reactivity and in vivo neutralisation of geographically diverse snake venoms

BACKGROUND

Snakebite is a neglected tropical disease that causes high global rates of mortality and morbidity. Although snakebite can cause a variety of pathologies in victims, haemotoxic effects are particularly common and are typically characterised by haemorrhage and/or venom-induced consumption coagulopathy. Antivenoms are the mainstay therapeutic for treating the toxic effects of snakebite, but despite saving thousands of lives annually, these therapies are associated with limited cross-snake species efficacy due to venom variation, which ultimately restricts their therapeutic utility to particular geographical regions.

METHODOLOGY/PRINCIPAL FINDINGS

In this study we explored the feasibility of generating globally effective pathology-specific antivenoms to counteract the haemotoxic signs of snakebite envenoming. Two different immunogen mixtures, consisting of seven and twelve haemotoxic venoms sourced from geographically diverse and/or medically important snakes, were used to raise ovine polyclonal antibodies, prior to characterisation of their immunological binding characteristics and in vitro neutralisation profiles against each of the venoms. Despite variability of the immunogen mixtures, both experimental antivenoms exhibited broadly comparable in vitro venom binding and neutralisation profiles against the individual venom immunogens in immunological and functional assays. However, in vivo assessments using a murine preclinical model of antivenom efficacy revealed substantial differences in venom neutralisation. The experimental antivenom generated from the seven venom immunogen mixture outperformed the comparator, by providing protective effects against venom lethality caused by seven of the eight geographically diverse venoms tested, including three distinct venoms that were not used as immunogens to generate this antivenom. These findings suggest that a core set of venom immunogens may be sufficient to stimulate antibodies capable of broadly neutralising a geographically diverse array of haemotoxic snake venoms, and that adding additional venom immunogens may impact negatively on the dose efficacy of the resulting antivenom.

CONCLUSIONS/SIGNIFICANCE

Although selection of appropriate immunogens that encapsulate venom toxin diversity without diluting antivenom potency remains challenging and further optimisation is required, the findings from this pilot study suggest that the generation of pathology-specific antivenoms with global utility is likely to feasible, thereby highlighting their promise as future modular treatments for the world's tropical snakebite victims.

Availability, affordability and stock-outs of commodities for the treatment of snakebite in Kenya

BACKGROUND

Annually, about 2.7 million snakebite envenomings occur globally. Alongside antivenom, patients usually require additional care to treat envenoming symptoms and antivenom side effects. Efforts are underway to improve snakebite care, but evidence from the ground to inform this is scarce. This study, therefore, investigated the availability, affordability, and stock-outs of antivenom and commodities for supportive snakebite care in health facilities across Kenya.

METHODOLOGY/PRINCIPAL FINDINGS

This study used an adaptation of the standardised World Health Organization (WHO)/Health Action International methodology. Data on commodity availability, prices and stock-outs were collected in July-August 2020 from public (n = 85), private (n = 36), and private not-for-profit (n = 12) facilities in Kenya. Stock-outs were measured retrospectively for a twelve-month period, enabling a comparison of a pre-COVID-19 period to stock-outs during COVID-19. Affordability was calculated using the wage of a lowest-paid government worker (LPGW) and the impoverishment approach. Accessibility was assessed combining the WHO availability target (≥80%) and LPGW affordability (<1 day's wage) measures. Overall availability of snakebite commodities was low (43.0%). Antivenom was available at 44.7% of public- and 19.4% of private facilities. Stock-outs of any snakebite commodity were common in the public- (18.6%) and private (11.7%) sectors, and had worsened during COVID-19 (10.6% versus 17.0% public sector, 8.4% versus 11.7% private sector). Affordability was not an issue in the public sector, while in the private sector the median cost of one vial of antivenom was 14.4 days' wage for an LPGW. Five commodities in the public sector and two in the private sector were deemed accessible.

CONCLUSIONS

Access to snakebite care is problematic in Kenya and seemed to have worsened during COVID-19. To improve access, efforts should focus on ensuring availability at both lower- and higher-level facilities, and improving the supply chain to reduce stock-outs. Including antivenom into Universal Health Coverage benefits packages would further facilitate accessibility.

R, Geevar T, Zachariah A, Sharma SK, Bhatt N, Mukaka M, Harriss E, Lalloo DG, Ashley EA, Monteiro WM, Smithuis F, Eddleston M. The 20-minute whole blood clotting test (20WBCT) for snakebite coagulopathy-A systematic review and meta-analysis of diagnostic test accuracy

BACKGROUND

The 20-minute whole blood clotting test (20WBCT) has been used to detect coagulopathy following snakebite for almost 50 years. A systematic review and meta-analysis of the 20WBCT was conducted to evaluate the accuracy of the 20WBCT to detect coagulopathy, indicative of systemic envenoming.

METHODS AND FINDINGS

Databases were searched from inception up to 09/12/2020 to identify studies that compared the 20WBCT and INR/fibrinogen on five or more subjects. Data was extracted from full-text articles by two reviewers using a predetermined form. Authors of 29 studies that lacked sufficient details in the manuscript were contacted and included if data meeting the inclusion criteria were provided. Included studies were evaluated for bias using a tailored QUADAS-2 checklist. The study protocol was prospectively registered on PROSPERO database (CRD42020168953). The searches identified 3,599 studies, 15 met the inclusion criteria and 12 were included in the meta-analysis. Data was reported from 6 countries and included a total of 2,270 patients. The aggregate weighted sensitivity of the 20WBCT at detecting INR >1.4 was 0.84 (CI 0.61 to 0.94), the specificity was 0.91 (0.76 to 0.97) and the SROC AUC was 0.94 (CI 0.91 to 0.96). The aggregate weighted sensitivity of the 20WBCT at detecting fibrinogen <100 mg/dL was 0.72 (CI 0.58 to 0.83), the specificity was 0.94 (CI 0.88 to 0.98) and the SROC AUC was 0.93 (0.91 to 0.95). Both analyses that used INR and fibrinogen as the reference test displayed considerable heterogeneity.

CONCLUSIONS

In the absence of laboratory clotting assays, the 20WBCT remains a highly specific and fairly sensitive bedside test at detecting coagulopathy following snakebite. However, clinicians should be aware of the importance of operator training, standardized equipment and the lower sensitivity of the 20WBCT at detecting mild coagulopathy and resolution of coagulopathy following antivenom.

Adjunct treatment in snakebite envenoming: a systematic review of randomised controlled trials

Adjunct therapy in snakebite may be lifesaving if administered appropriately or can be harmful if non-judicious use leads to avoidable delays in administering antivenom. This systematic review analyses the evidence from randomised controlled trials (RCTs) on the efficacy of adjunct treatment administered with antivenom. PubMed, EMBASE, Scopus, Cochrane library and CINAHL were searched for RCTs enrolling patients with snakebite envenoming where a treatment other than antivenom has been assessed for its efficacy within the last 25 y. Fifteen studies met the inclusion criteria. The interventions assessed were categorised as adjunct therapies (heparin or fresh frozen plasma) to reverse haemotoxicity (three studies), antibiotics to prevent local infections (three studies), steroids to reduce local swelling (one study), premedication (adrenaline, steroids and antihistamines, either alone or in combination) to reduce hypersensitivity reactions to antivenom (five studies) and other interventions (three studies). Apart from a beneficial effect of low-dose adrenaline (1:1000, 0.25 ml administered subcutaneously) in preventing antivenom-induced hypersensitivities (OR: 0.54, 95% CI 0.32 to 0.93, two RCTs, 354 participants, moderate certainty evidence) in Sri Lanka, evidence for any other adjunct therapy is either non-existent or needs confirmation by larger better designed trials.

Evaluation of The effects of Anti-Inflammatory Drugs on Local and Systemic manifestations of snakebite: A cross-sectional study

Although the predominant treatment for snakebite is the antivenom, other treatments are also considered. We studied the effects of single or multiple-doses of anti-inflammatory drugs on local, systemic and laboratory findings of the snakebite victims. In this cross-sectional study, 101 patients (90 male: 89.1%) with snakebite envenomation who were admitted to the Medical Toxicology Center of Khorshid Hospital, Isfahan, Iran, were investigated. One group (35 patients: 34.7%) received a single-dose of anti-inflammatory drugs containing chlorpheniramine (10mg intramuscular injection) with cimetidine (200mg intravenous injection) or ranitidine (50mg intravenous injection) plus hydrocortisone (100mg intravenous injection). The other 55 patients (54.5%) received multiple doses of the same drug combination every 8hr until the symptoms resolved. Local, systemic symptoms and laboratory findings on admission, and during 24hr and 48hr of admission, were recorded. The frequency of the localized signs of inflammation (p=0.03), swelling (p<0.001) and bruising (p<0.001) showed a significant difference between the two treated groups. In addition, the recovery time in the patients who received multiple doses was faster (p<0.001). There was no significant difference in any of the systemic signs, laboratory findings or the outcome between the patients in the various groups during hospitalization. Our data indicate that the administration of multiple doses of anti-inflammatory drugs had a greater effect on reducing local symptoms of snakebite including inflammatory manifestations.

Comparison of rotational thromboelastometry parameters with 20-minute whole blood clotting test as a predictor of envenoming in Russell's viper bite patients

BACKGROUND

Coagulopathy is an important and common systemic clinical syndrome caused by snake envenoming. The major clinical effect of Russell's viper (RV) envenoming is haematotoxicity. The 20-min whole blood clotting test (WBCT20) is the standard test for identification of envenoming in resource-limited settings. However, its reliability as a diagnostic test has been questioned. Rotational thromboelastometry (ROTEM) assays different phases of clot formation from initiation to fibrinolysis. Our objective was to compare parameters of ROTEM with WBCT20 and the international normalized ratio (INR) as predictors of envenoming in RV bite patients.

METHODS

Fifty-three patents with RV bite presenting to Anuradhapura Hospital, Sri Lanka were recruited. Epidemiological and clinical data were obtained. Venous blood samples were collected at admission for ROTEM, INR and WBCT20.

RESULTS

A total of 46 of 53 patients with RV bites received antivenom serum (AVS); 74% had a non-clottable WBCT20. All 46 had at least one abnormal ROTEM parameter and 93% had a prolonged EXTEM clotting time (EXTEM-CT). The sensitivity of a prolonged INR was only 55%.

CONCLUSIONS

EXTEM-CT is a better predictor of envenoming and the need for AVS than WBCT20 in RV bites (p=0.02). It provides a numerical value that can be used post-AVS to objectively assess the response and decide on further treatment.

Diagnosing, managing and preventing anaphylaxis: Systematic review

BACKGROUND

This systematic review used the GRADE approach to compile evidence to inform the European Academy of Allergy and Clinical Immunology's (EAACI) anaphylaxis guideline.

METHODS

We searched five bibliographic databases from 1946 to 20 April 2020 for studies about the diagnosis, management and prevention of anaphylaxis. We included 50 studies with 18 449 participants: 29 randomized controlled trials, seven controlled clinical trials, seven consecutive case series and seven case-control studies. Findings were summarized narratively because studies were too heterogeneous to conduct meta-analysis.

RESULTS

It is unclear whether the NIAID/FAAN criteria or Brighton case definition are valid for immediately diagnosing anaphylaxis due to the very low certainty of evidence. There was also insufficient evidence about the impact of most anaphylaxis management and prevention strategies. Adrenaline is regularly used for first-line emergency management of anaphylaxis but little robust research has assessed its effectiveness. Newer models of adrenaline autoinjectors may slightly increase the proportion of people correctly using the devices and reduce time to administration. Face-to-face training for laypeople may slightly improve anaphylaxis knowledge and competence in using autoinjectors. We searched for but found little or no comparative effectiveness evidence about strategies such as fluid replacement, oxygen, glucocorticosteroids, methylxanthines, bronchodilators, management plans, food labels, drug labels and similar.

CONCLUSIONS

Anaphylaxis is a potentially life-threatening condition but, due to practical and ethical challenges, there is a paucity of robust evidence about how to diagnose and manage it.

Single-Arm, Multicenter Phase I/II Clinical Trial for the Treatment of Envenomings by Massive Africanized Honey Bee Stings Using the Unique Apilic Antivenom

We evaluated the safety, optimal dose, and preliminary effectiveness of a new-approach Africanized honeybee (Apis mellifera) Antivenom (AAV) in a phase I/II, multicenter, non-randomized, single-arm clinical trial involving 20 participants with multiple stings. Participants received 2 to 10 vials of AAV depending on the number of stings they suffered, or a predefined adjuvant, symptomatic, and complementary treatment. The primary safety endpoint was the occurrence of early adverse reactions within the first 24 h of treatment. Preliminary efficacy based on clinical evolution, including laboratory findings, was assessed at baseline and at various time points over the four following weeks. ELISA assays and mass spectrometry were used to estimate venom pharmacokinetics before, during, and after treatment. Twenty adult participants, i.e., 13 (65%) men and 7 (35%) women, with a median age of 44 years and a mean body surface area of 1.92 m² (median = 1.93 m²) were recruited. The number of stings ranged from 7 to > 2,000, with a median of 52.5. Symptoms of envenoming were classified as mild, moderate, or severe in 80% (16), 15% (3), and 5% (1) of patients, respectively; patients with mild, moderate, or severe envenoming received 2, 6, and 10 vials of AAV as per the protocol. None of the patients had late reactions (serum sickness) within 30 d of treatment. There was no discontinuation of the protocol due to adverse events, and there were no serious adverse events. One patient had a moderate adverse event, transient itchy skin, and erythroderma. All participants completed the intravenous antivenom infusion within 2 h, and there was no loss to follow-up after discharge. ELISA assays showed venom (melittin and PLA₂) concentrations varying between 0.25 and 1.479 ng/mL prior to treatment. Venom levels decreased in all patients during the hospitalization period. Surprisingly, in nine cases (45%), despite clinical recovery and the absence of symptoms, venom levels increased again during outpatient care 10 d after discharge. Mass spectrometry showed melittin in eight participants, 30 d after treatment. Considering the promising safety results for this investigational product in the treatment of massive Africanized honeybee attack, and its efficacy, reflected in the clinical improvements and corresponding immediate decrease in blood venom levels, the AAV has shown to be safe for human use. Clinical Trial Registration: UTN: U1111-1160-7011, identifier [RBR-3fthf8].

Association of a Network of Immunologic Response and Clinical Features With the Functional Recovery From Crotalinae Snakebite Envenoming

Background

The immunologic pathways activated during snakebite envenoming (SBE) are poorly described, and their association with recovery is unclear. The immunologic response in SBE could inform a prognostic model to predict recovery. The purpose of this study was to develop pre- and post-antivenom prognostic models comprised of clinical features and immunologic cytokine data that are associated with recovery from SBE.

Materials and Methods

We performed a prospective cohort study in an academic medical center emergency department. We enrolled consecutive patients with Crotalinae SBE and obtained serum samples based on previously described criteria for the Surgical Critical Care Initiative (SC2i)(ClinicalTrials.gov Identifier: NCT02182180). We assessed a standard set of clinical variables and measured 35 unique cytokines using Luminex Cytokine 35-Plex Human Panel pre- and post-antivenom administration. The Patient-Specific Functional Scale (PSFS), a well-validated patient-reported outcome of functional recovery, was assessed at 0, 7, 14, 21 and 28 days and the area under the patient curve (PSFS AUPC) determined. We performed Bayesian Belief Network (BBN) modeling to represent relationships with a diagram composed of nodes and arcs. Each node represents a cytokine or clinical feature and each arc represents a joint-probability distribution (JPD).

Results

Twenty-eight SBE patients were enrolled. Preliminary results from 24 patients with clinical data, 9 patients with pre-antivenom and 11 patients with post-antivenom cytokine data are presented. The group was mostly female (82%) with a mean age of 38.1 (SD ± 9.8) years. In the pre-antivenom model, the variables most closely associated with the PSFS AUPC are predominantly clinical features. In the post-antivenom model, cytokines are more fully incorporated into the model. The variables most closely associated with the PSFS AUPC are age, antihistamines, white blood cell count (WBC), HGF, CCL5 and VEGF. The most influential variables are age, antihistamines and EGF. Both the pre- and post-antivenom models perform well with AUCs of 0.87 and 0.90 respectively.

Discussion

Pre- and post-antivenom networks of cytokines and clinical features were associated with functional recovery measured by the PSFS AUPC over 28 days. With additional data, we can identify prognostic models using immunologic and clinical variables to predict recovery from SBE.

Protein decomplexation and proteomics: A complementary assessment method of the physicochemical purity of antivenom

The quality of antivenom is governed by its safety and efficacy profiles. These quality characteristics are much influenced by the purity of antivenom content. Rigorous assessment and meticulous monitoring of antivenom purity at the preclinical setting is hence crucial. This study aimed to explore an integrative proteomic method to assess the physicochemical purity of four commercially available antivenoms in the region. The antivenoms were subjected to Superdex 200 HR 10/30 size-exclusion fast-protein liquid chromatography (SE-FPLC). The proteins in each fraction were trypsin-digested and analyzed by nano-ESI-liquid chromatography-tandem mass spectrometry (LC-MS/MS). SE-FPLC resolved the antivenom proteins into three major protein components of very high (>200 kDa), high (100-120 kDa) and medium (<60 kDa) molecular weights. The major components (80-95% of total proteins) in the antivenoms were proteins of 100-120 kDa consisting of mainly the light and partially digested heavy immunoglobulin chains, consistent with F(ab')₂ as the active principle of the antivenoms. However, LC-MS/MS also detected substantial quantity of large proteins (e.g. alpha-2-macroglobulins), immunoglobulin aggregates and impurities e.g. albumins in some products. The method is practical and able to unveil the quantitative and qualitative aspects of antivenom protein compositions. It is therefore a potentially useful preclinical assessment tool of antivenom purity.

Paediatric snakebite envenoming: recognition and management of cases

Snakebite in children can often be severe or potentially fatal, owing to the lower volume of distribution relative to the amount of venom injected, and there is potential for long-term sequelae. In the second of a two paper series, we describe the pathophysiology of snakebite envenoming including the local and systemic effects. We also describe the diagnosis and management of snakebite envenoming including prehospital first aid and definitive medical and surgical care.

Prospective review of cytotoxic snakebite envenomation in a paediatric population

Cytotoxic snakebite envenomation is prevalent in Kwazulu-Natal and may be associated with significant physical disability. The aim of this study was to provide an overview of the effects of cytotoxic envenomation in children. The patient population were all patients attending the Emergency Department at Ngwelezana Tertiary Hospital with snakebite from December 2014 to March 2015. All children 13 years or younger presenting with painful progressive swelling (PPS) following snakebite were included in this study. They were further classified according to severity: mild, moderate and severe. Patient demographic and clinical data was collected prospectively. Fifty-one children were included in this study. Nine were classified as mild, 24 as moderate and 18 as severe. The median time of presentation after bite was 6 h in the mild group, 7 h in the moderate group and 12 h in the severe group. There was a positive correlation between increasing severity and INR (p=< .00001) and no correlation between WCC (p = .175) or renal function and severity (p = .963). A total of 11 children (22%) developed an acute kidney injury (AKI). A total of 23/51 patients received antivenom; 25% of patients with moderate cytotoxicity and 94% of patients with severe cytotoxicity. Thirteen percent developed allergic reactions (3/23) and 57% (13/23) anaphylaxis. A total of 15 patients underwent one or more procedures on their affected limbs. There was one recorded mortality during this period, related to severe anaphylaxis following antivenom administration. Access to healthcare for antivenom administration is often delayed and ongoing education within affected areas is advised. Whilst majority of snakebite victims can be adequately managed with basic supportive measures, early identification of severe envenomation is crucial to enable timeous antivenom administration and prevention of further complications such as compartment syndrome and loss of limb. Hypersensitivity reactions are alarmingly common following antivenom administration in children and strict protocols should be followed when administering antivenom.

A therapeutic combination of two small molecule toxin inhibitors provides broad preclinical efficacy against viper snakebite

Snakebite is a medical emergency causing high mortality and morbidity in rural tropical communities that typically experience delayed access to unaffordable therapeutics. Viperid snakes are responsible for the majority of envenomings, but extensive interspecific variation in venom composition dictates that different antivenom treatments are used in different parts of the world, resulting in clinical and financial snakebite management challenges. Here, we show that a number of repurposed Phase 2-approved small molecules are capable of broadly neutralizing distinct viper venom bioactivities in vitro by inhibiting different enzymatic toxin families. Furthermore, using murine in vivo models of envenoming, we demonstrate that a single dose of a rationally-selected dual inhibitor combination consisting of marimastat and varespladib prevents murine lethality caused by venom from the most medically-important vipers of Africa, South Asia and Central America. Our findings support the translation of combinations of repurposed small molecule-based toxin inhibitors as broad-spectrum therapeutics for snakebite.

Exotic Snakebites Reported to Pennsylvania Poison Control Centers: Lessons Learned on the Demographics, Clinical Effects, and Treatment of These Cases

Exotic snakebites (i.e. from non-native species) are a rare occurrence, but they present a unique challenge to clinicians treating these patients. Poison control centers are often contacted to assist in the management and care of these medical emergencies. In this study, we analyzed case records of the two Pennsylvania poison control centers from 2004 to 2018 to describe clinical features reported as a result of exotic snakebite envenomation. For the 15-year period reviewed, 18 exotic snakebites were reported with effects ranging from mild local tissue injury to patients who were treated with mechanical ventilation due to respiratory failure. The mean age of the patients was 35 years and males accounted for 83% of the cases. Antivenom, the only specific treatment, was administered in seven of 18 patients within an average of four h of envenomation. The procurement of antivenom against these exotic species may require substantial logistical efforts due to limited stocking of this rarely used treatment. Newer, targeted, small molecule treatments that are being currently investigated may aid in the treatment of snakebites in general. However, people should be cautious when handling these exotic species, and clinicians should be aware of these bites and relevant clinical effects in order to manage these when reported.

Severe hypofibrinogenemia in patients bitten by Gloydius tsushimaensis in Tsushima Island, Nagasaki, Japan, and treatment strategy

Gloydius tsushimaensis is an endemic species inhabiting only Tsushima, a remote Japanese island, and is a distinct species from Gloydius blomhoffii widely distributed throughout mainland Japan and Gloydius brevicaudus and Gloydius ussuriensis which are geographically distributed in South Korea. This is the first multicenter retrospective study of G. tsushimaensis bites in Japan. A study of seventy-two patients who visited the former Izuhara Hospital, the former Naka Tsushima Hospital, Tsushima Hospital, and Kamitsushima Hospital during the fourteen years from January 1, 2005, to December 31, 2018, revealed the typical clinical characteristics of G. tsushimaensis bites. Five out of seventy-two cases (6.9%) showed severe hypofibrinogenemia, in which fibrinogen levels were below 100 mg/dl, which is an unreported clinical finding for G. blomhoffii bites. Generally, when fibrinogen levels are lower than 100 mg/dl, the bleeding risk increases, and it is perilous. Severe hypofibrinogenemia cases did not improve after G. blomhoffii antivenom administration. Additionally, all five cases had disseminated intravascular coagulation, and there were two cases of acute kidney injury and one death. five cases had a median maximum creatine kinase level of 5171 IU/l (Interquartile range: 4992-41,310). Although the mechanism is not precise, coagulation tests showed that the G. tsushimaensis venom contains a thrombin-like enzyme. Based on this research, we created an algorithm for the treatment of G. tsushimaensis bites and unified the treatment methods used on the island.

New insights into snakebite epidemiology in Costa Rica: A retrospective evaluation of medical records

Continuous monitoring of the snakebite envenoming allows elucidating factors that affect its incidence at spatial and temporal scales, and is a great tool to evaluate the proper management of snakebite in health centers. To determine if there have been changes over time in snakebite epidemiology in Costa Rica, we conducted a retrospective study using medical records from six hospitals for the years 2012-2013. A total of 475 snakebite patients were treated at the selected hospital during this period. Most bites occurred during the rainy season and primarily affected young men, mainly farm workers and schoolchildren. About 55% of bites occur in peri-domiciliary environments, although its prevalence varies geographically. Bothrops asper generates the vast majority of envenoming in the country, which is why the main local symptoms registered are edema, pain, and bleeding disorders. The time elapsed until treatment did not explain the degree of severity at admission. However, complications were observed more frequently in patients who took longer to receive treatment. The primary complications were bacterial infections, whereas kidney failure and compartment syndrome documented at very low frequencies. Only one death was recorded, reflecting the low fatality rate exhibited in the country. Hospital treatment included the rapid administration of antivenom and complementary treatment of antibiotics, analgesics, and antihistamines. The application of the latter as prophylactic does not seem to prevent the appearance of mild early adverse reactions, registered in 22.5% of the cases. Morbidity and mortality rates from snakebite have continued to decrease in the country, as a result of the efforts that Costa Rica has made to improve its public health system. Among those efforts, the creation of primary care centers (EBAIS) has reduced the time to treatment in many regions of the country. The Costa Rican experience of using antivenom in primary health care centers and maintaining good medical records could be considered for application in other countries where snakebite is a major health problem.

Adverse Reactions after Administration of Antivenom in Korea

Kovax® antivenom is the main treatment for toxins produced by the Gloydius species. However, research on adverse reactions after Kovax® antivenom administration is scarce. We aimed to identify the incidence and characteristics of adverse reactions after Kovax® antivenom administration. We conducted a retrospective review of the medical records of snakebite patients in Korea between January 2008 and September 2019. We identified the frequency, characteristics, and treatments of adverse reactions to Kovax® antivenom. There were 150 patients with snakebites, of whom 121 (80.7%) patients received Kovax® antivenom. Adverse reactions occurred in five patients (4.1%). Acute adverse reactions within 24 h of antivenom administration occurred in two patients (1.7%). The symptoms of patients with acute adverse reactions were nausea, diaphoresis, dizziness, and hypotension. Delayed adverse reactions that occurred 24 h after antivenom administration were reported in three patients (2.5%). One patient had a skin rash after 10 days, and two patients had fever 37 and 48 h after antivenom use. In conclusion, most patients were managed safely after Kovax® antivenom, and the incidence of adverse reactions was low. Severe adverse reactions occurred in a small percentage of patients, and there were no deaths.

Preclinical validation of a repurposed metal chelator as an early-intervention therapeutic for hemotoxic snakebite

Snakebite envenoming causes 138,000 deaths annually, and ~400,000 victims are left with permanent disabilities. Envenoming by saw-scaled vipers (Viperidae: Echis) leads to systemic hemorrhage and coagulopathy and represents a major cause of snakebite mortality and morbidity in Africa and Asia. The only specific treatment for snakebite, antivenom, has poor specificity and low affordability and must be administered in clinical settings because of its intravenous delivery and high rates of adverse reactions. This requirement results in major treatment delays in resource-poor regions and substantially affects patient outcomes after envenoming. Here, we investigated the value of metal ion chelators as prehospital therapeutics for snakebite. Among the tested chelators, dimercaprol (British anti-Lewisite) and its derivative 2,3-dimercapto-1-propanesulfonic acid (DMPS) were found to potently antagonize the activity of Zn2+-dependent snake venom metalloproteinases in vitro. Moreover, DMPS prolonged or conferred complete survival in murine preclinical models of envenoming against a variety of saw-scaled viper venoms. DMPS also considerably extended survival in a "challenge and treat" model, where drug administration was delayed after venom injection and the oral administration of this chelator provided partial protection against envenoming. Last, the potential clinical scenario of early oral DMPS therapy combined with a delayed, intravenous dose of conventional antivenom provided prolonged protection against the lethal effects of envenoming in vivo. Our findings demonstrate that the safe and affordable repurposed metal chelator DMPS can effectively neutralize saw-scaled viper venoms in vitro and in vivo and highlight the promise of this drug as an early, prehospital, therapeutic intervention for hemotoxic snakebite envenoming.

Venomous Bites, Stings, and Poisoning: An Update

This article discusses the epidemiology, prevention, clinical features, and treatment of venomous bites by snakes, lizards, and spiders; stings by fish, jellyfish, echinoderms, insects, and scorpions; and poisoning by ingestion of fish, turtles, and shellfish. Invertebrate stings cause fatalities by anaphylaxis, secondary to acquired hypersensitivity (Hymenoptera, such as bees, wasps, and ants; and jellyfish), and by direct envenoming (scorpions, spiders, jellyfish, and echinoderms). Simple preventive techniques, such as wearing protective clothing, using a flashlight at night, and excluding venomous animals from sleeping quarters, are of paramount importance to reduce the risk of venomous bites and stings.

The Urgent Need to Develop Novel Strategies for the Diagnosis and Treatment of Snakebites

Snakebite envenoming (SBE) is a priority neglected tropical disease, which kills in excess of 100,000 people per year. Additionally, many millions of survivors also suffer through disabilities and long-term health consequences. The only treatment for SBE, antivenom, has a number of major associated problems, not least, adverse reactions and limited availability. This emphasises the necessity for urgent improvements to the management of this disease. Administration of antivenom is too frequently based on symptomatology, which results in wasting crucial time. The majority of SBE-affected regions rely on broad-spectrum polyvalent antivenoms that have a low content of case-specific efficacious immunoglobulins. Research into small molecular therapeutics such as varespladib/methyl-varespladib (PLA2 inhibitors) and batimastat/marimastat (metalloprotease inhibitors) suggest that such adjunctive treatments could be hugely beneficial to victims. Progress into toxin-specific monoclonal antibodies as well as alternative binding scaffolds such as aptamers hold much promise for future treatment strategies. SBE is not implicit during snakebite, due to venom metering. Thus, the delay between bite and symptom presentation is critical and when symptoms appear it may often already be too late to effectively treat SBE. The development of reliable diagnostical tools could therefore initiate a paradigm shift in the treatment of SBE. While the complete eradication of SBE is an impossibility, mitigation is in the pipeline, with new treatments and diagnostics rapidly emerging. Here we critically review the urgent necessity for the development of diagnostic tools and improved therapeutics to mitigate the deaths and disabilities caused by SBE.

Acute Severe Anaphylaxis in Nepali Patients with Neurotoxic Snakebite Envenoming Treated with the VINS Polyvalent Antivenom

Diagnosing and treating acute severe and recurrent antivenom-related anaphylaxis (ARA) is challenging and reported experience is limited. Herein, we describe our experience of severe ARA in patients with neurotoxic snakebite envenoming in Nepal. Patients were enrolled in a randomised, double-blind trial of high vs. low dose antivenom, given by intravenous (IV) push, followed by infusion. Training in ARA management emphasised stopping antivenom and giving intramuscular (IM) adrenaline, IV hydrocortisone, and IV chlorphenamine at the first sign/s of ARA. Later, IV adrenaline infusion (IVAI) was introduced for patients with antecedent ARA requiring additional antivenom infusions. Preantivenom subcutaneous adrenaline (SCAd) was introduced in the second study year (2012). Of 155 envenomed patients who received ≥ 1 antivenom dose, 13 (8.4%), three children (aged 5−11 years) and 10 adults (18−52 years), developed clinical features consistent with severe ARA, including six with overlapping signs of severe envenoming. Four and nine patients received low and high dose antivenom, respectively, and six had received SCAd. Principal signs of severe ARA were dyspnoea alone (n=5 patients), dyspnoea with wheezing (n=3), hypotension (n=3), shock (n=3), restlessness (n=3), respiratory/cardiorespiratory arrest (n=7), and early (n=1) and late laryngeal oedema (n=1); rash was associated with severe ARA in 10 patients. Four patients were given IVAI. Of the 8 (5.1%) deaths, three occurred in transit to hospital. Severe ARA was common and recurrent and had overlapping signs with severe neurotoxic envenoming. Optimising the management of ARA at different healthy system levels needs more research. This trial is registered with NCT01284855.

Utility of Clot Waveform Analysis in Russell's Viper Bite Victims with Hematotoxicity

Introduction:

In Russell's viper bites, due to the lack of a better alternative, whole blood clotting test (WBCT) remains the standard test even though its reliability and sensitivity has been shown to be low. Activated partial thromboplastin time (aPTT)-based clot waveform analysis (CWA) is an optic absorbance assay that can be used as a global clotting test. In this study, the objective was to assess the changes in CWA and to compare CWA to WBCT and aPTT in patients with Russell's viper envenomation.

Methods:

The datum was collected prospectively over 2 months as a pilot observational study in a tertiary care center. All proven cases of Russell's viper-envenomated individuals with preliminary CWA data and WBCT were included in the study. The clot wave (CW) of the five individuals, which met all the stringent inclusion criteria, was analyzed and interpreted.

Results:

CW absorbance sigmoid waveform was deranged in all 5 cases, of which 4 showed a change in CWA even before an abnormal aPTT. Three of the 5 had a normal WBCT but showed early changes in CWA. Atypical biphasic waveform reported in disseminated intravascular coagulation in other prior studies is seen in venom-induced consumptive coagulopathy also. In all patients where a second derivative was plotted, the second (lower) phase of the second derivative showed a slow rise to baseline.

Conclusion:

CWA showed changes which provided information earlier than the conventional coagulation studies in the snakebite victims studied. While aPTT or WBCT reflects clotting time, CWA conveys the dynamic process of clot formation and stabilization. CWA may reveal disorders of clotting in snakebite victims before the conventional tests become abnormal. Future research should assess the speed and accuracy of the test in diagnosing hemotoxic envenomation and its potential role in guiding antivenom therapy.