Venom-Induced Consumption Coagulopathy Unresponsive to Antivenom After Echis carinatus sochureki Envenoming

From birth to bite: the evolutionary ecology of India's medically most important snake venoms

BACKGROUND

Snake venoms can exhibit remarkable inter- and intraspecific variation. While diverse ecological and environmental factors are theorised to explain this variation, only a handful of studies have attempted to unravel their precise roles. This knowledge gap not only impedes our understanding of venom evolution but may also have dire consequences on snakebite treatment. To address this shortcoming, we investigated the evolutionary ecology of venoms of Russell's viper (Daboia russelii) and spectacled cobra (Naja naja), India's two clinically most important snakes responsible for an alarming number of human deaths and disabilities.

METHODOLOGY

Several individuals (n = 226) of D. russelii and N. naja belonging to multiple clutches (n = 9) and their mothers were maintained in captivity to source ontogenetic stage-specific venoms. Using various in vitro and in vivo assays, we assessed the significance of prey, ontogeny and sex in driving venom composition, function, and potency.

RESULTS

Considerable ontogenetic shifts in venom profiles were observed in D. russelii, with the venoms of newborns being many times as potent as juveniles and adults against mammalian (2.3-2.5 ×) and reptilian (2-10 ×) prey. This is the first documentation of the ontogenetic shift in viperine snakes. In stark contrast, N. naja, which shares a biogeographic distribution similar to D. russelii, deployed identical biochemical cocktails across development. Furthermore, the binding kinetics of cobra venom toxins against synthetic target receptors from various prey and predators shed light on the evolutionary arms race.

CONCLUSIONS

Our findings, therefore, provide fascinating insights into the roles of ecology and life history traits in shaping snake venoms.

Successful Management of Severe Unresponsive Snake Bite Envenomation Using Plasmapheresis and Corticosteroid at Egyptian National Environmental and Clinical Toxicology Research Center: A Case Report

Snakebite is a significant public health issue in which venom-induced consumption coagulopathy is a common and serious complication that results from the activation of the coagulation pathway by snake toxins. We report a male patient, 56 y old, who was thought to have been bitten by a snake on his left foot. He was transported to a nearby hospital where he received analgesics and 3 snake polyvalent antivenom vials, and then he was transported to our hospital after 12 h. He presented with 2 small puncture wounds, pain, blistering, and edema of the left foot. On the 2nd day, the patient developed gingival bleeding and hematuria. Laboratory investigations upon admission revealed prothrombin time (PT) of more than 3 min, prothrombin concentration (PC) of less than 2.5%, and an international normalized ratio (INR) of 23.43. Further investigation of urine showed more than 100 RBCs. Despite receiving 16 packs of plasma and 40 snake polyvalent antivenom vials manufactured by VACSERA over 3 days, hemoglobin concentration and platelet count decreased with the appearance of jaundice, lactate dehydrogenase was 520, and reticulocytes were 3.5%. PT was more than 300 s, and INR was still over range. Plasmapheresis and corticosteroids were provided, which improved the patient's general condition, PT, PC, and INR, and the patient was discharged after 6 days of hospital stay. This case report indicated that plasmapheresis and corticosteroids were clinically efficient approaches in the management of snake envenomation unresponsive to antivenom.

Immunoreactivity and neutralization efficacy of Pakistani Viper Antivenom (PVAV) against venoms of Saw-scaled Vipers (Echis carinatus subspp.) and Western Russell's Vipers (Daboia russelii) from the Indian subcontinent

Snakebite envenoming (SBE) is a priority Neglected Tropical Disease listed by the World Health Organization. South Asia is heavily affected, and virtually all countries in the region import polyvalent antivenom products from India for clinical use. The imported antivenoms, however, have suboptimal effectiveness due to geographical venom variation. Recently, a domestic bivalent product, named Pakistani Viper Antivenom (PVAV) has been developed specifically for Pakistani vipers, Echis carinatus sochureki and Daboia russelii. As a bivalent viperid antivenom, it is unknown yet if PVAV exhibits higher immunological binding and neutralization activities against viper venoms from distant locales compared with polyvalent antivenoms manufactured in India. This study thus examined the preclinical efficacy of PVAV against venoms of Western Russell's Vipers and Saw-scaled Viper subspecies from selected locales in the Indian subcontinent. PVAV generally outperformed the commonly used VINS polyvalent antivenom (VPAV, manufactured in India) in binding toward venoms, and showed superior or comparable neutralization efficacy against the venom procoagulant and hemorrhagic effects of Saw-scaled Vipers as well as Russell's Vipers from Pakistan and Sri Lanka. Based on normalized potency values, PVAV is far more potent than VPAV in neutralizing the lethality of all viper venoms, except that of the Indian Russell's Viper. The study shows conserved antigenicity of toxins responsible for major toxicity across these viperid venoms, and suggests the feasible production of a viper-specific antivenom with higher potency and broader geographical utility for the region.

Delayed Compression Paralysis Following an Iliopsoas Hematoma 30 Days After Saw-Scaled Viper (Echis carinatus sochureki) Envenoming: A Case Report

Snakebite envenoming is a neglected tropical disease disproportionately affecting the rural and marginalized population in low-middle-income countries. The saw-scaled viper (Echis carinatus) is a clinically important snake that causes serious morbidity and mortality in the Indian subcontinent. Even though it is within the so-called big-four snakes against which polyvalent antivenom is available throughout India, reports of antivenom ineffectiveness are emerging in saw-scaled viper envenoming, especially around Jodhpur, Rajasthan, India. This case report highlights a patient with saw-scaled viper envenoming with an ineffective antivenom response complicated by acute kidney injury as well as local and systemic bleeding complications, which subsequently resulted in a pelvic hematoma that compressed the lumbosacral nerves, causing lower-limb weakness and sensory deficits. He was successfully managed with hematoma aspiration and supportive care. This case brings into focus the challenges of managing saw-scaled viper envenoming in this region with antivenom ineffectiveness, resulting in delayed and significant coagulopathy and its complications leading to prolonged hospital stay and morbidity. Our report spotlights less emphasized aspects of long-term morbidity in snakebite survivors, such as loss of working days and productivity. We also highlight the need for an organized system of long-term follow-up of snakebite survivors to screen for possible complications and manage them early.

The Need for Next-Generation Antivenom for Snakebite Envenomation in India

The limitations posed by currently available antivenoms have emphasized the need for alternative treatments to counteract snakebite envenomation. Even though exact epidemiological data are lacking, reports have indicated that most global snakebite deaths are reported in India. Among the many problems associated with snakebite envenomation, issues related to the availability of safer and more efficient antivenoms are of primary concern. Since India has the highest number of global snakebite deaths, efforts should be made to reduce the burden associated with snakebite envenoming. Alternative methods, including aptamers, camel antivenoms, phage display techniques for generating high-affinity antibodies and antibody fragments, small-molecule inhibitors, and natural products, are currently being investigated for their effectiveness. These alternative methods have shown promise in vitro, but their in vivo effectiveness should also be evaluated. In this review, the issues associated with Indian polyvalent antivenoms in neutralizing venom components from geographically distant species are discussed in detail. In a nutshell, this review gives an overview of the current drawbacks of using animal-derived antivenoms and several alternative strategies that are currently being widely explored.

Redefining the role of therapeutic plasma exchange in complications of Echis carinatus sochureki envenomation refractory to anti-snake venom: A case series

INTRODUCTION

Saw-scaled viper (Echis carinatus) belongs to the Viperidae family. Its venom is hemotoxic and contains several small peptides and proteins affecting the coagulation system. Commonly used anti-snake venom (ASV) products in India are reported to be ineffective or less effective in cases with bites by Echis carinatus sochureki which are commonly found in desert areas in Rajasthan. Although therapeutic plasma exchange (TPE) has been successful in patients with snakebite envenomation in the past, American Society for Apheresis guidelines 2019 included this indication under category III with grade 2C recommendation.

AIM AND OBJECTIVES

To report the safety and efficacy of therapeutic plasma exchange procedures in the setting of ASV refractory E. c. sochureki envenomation.

MATERIALS AND METHODS

Four patients admitted to our institute in 2021 September with an alleged history of snake bites and who underwent at least one cycle of therapeutic plasma exchange were assessed for clinical outcome, laboratory parameters, and blood product consumption.

RESULTS

Three adult patients and one pediatric patient are included in this case series, all of them males. Indication for TPE in one case was suspected diffuse alveolar hemorrhage (DAH), while in all the other cases was thrombotic microangiopathy (TMA). All received a variable number of sessions from 2 to 5 and 1.3-1.5 plasma volume was removed on an average per cycle. The endpoint of TPE was the resolution of DAH in one while a reduction in lactate dehydrogenase and an increase in platelet count was in TMA cases. Consumption of blood products was drastically reduced in all four patients after starting the procedure. All the adult patients fared well on follow-up while the child had developed acute cortical necrosis and was dialysis-dependent. It has been noted in the previous studies too that a subset of snakebite-induced TMA cases was getting converted to chronic kidney disease and becoming dialysis dependent in the long run.

CONCLUSIONS

In regions where ASV treatment failure is very common, therapeutic plasma exchange is a safe and effective complementary treatment modality along with supportive care.

Proteomic Analysis, Immuno-Specificity and Neutralization Efficacy of Pakistani Viper Antivenom (PVAV), a Bivalent Anti-Viperid Antivenom Produced in Pakistan

Snakebite envenoming is a neglected tropical disease prevalent in South Asia. In Pakistan, antivenoms are commonly imported from India despite the controversy over their effectiveness. To solve the problem, the locals have developed the Pakistani Viper Antivenom (PVAV), raised against Sochurek’s Saw-scaled Viper (Echis carinatus sochureki) and Russell’s Viper (Daboia russelii) of Pakistani origin. This study is set to evaluate the composition purity, immuno-specificity and neutralization efficacy of PVAV. Chromatographic and electrophoretic profiling coupled with proteomic mass spectrometry analysis showed PVAV containing high-purity immunoglobulin G with minimum impurities, notably the absence of serum albumin. PVAV is highly immuno-specific toward the venoms of the two vipers and Echis carinatus multisquamatus, which are indigenous to Pakistan. Its immunoreactivity, however, reduces toward the venoms of other Echis carinatus subspecies and D. russelii from South India as well as Sri Lanka. Meanwhile, its non-specific binding activities for the venoms of Hump-nosed Pit Vipers, Indian Cobras and kraits were extremely low. In the neutralization study, PVAV effectively mitigated the hemotoxic and lethal effects of the Pakistani viper venoms, tested in vitro and in vivo. Together, the findings suggest the potential utility of PVAV as a new domestic antivenom for the treatment of viperid envenoming in Pakistan.

Venom-induced consumptive coagulopathy leading to thrombotic microangiopathy following Echis carinatus sochureki bite: is snake antivenom effective?

The incidence of thrombotic microangiopathy (TMA) following snake bite is reported to be ranging from 3.6 to 15%. We report a 10-year-old boy who developed TMA and due to venom-induced consumptive coagulopathy (VICC) despite receiving adequate and timely doses of snake antivenom following a bite of saw-scaled viper (Echis carinatus sochureki). VICC was managed by plasmapheresis. Though snake bite envenomation-associated renal complications are not uncommon, possibility of TMA should be considered early during management. Our patient developed TMA with subsequent acute cortical necrosis after saw-scaled viper bite despite an adequate and timely dose of snake antivenom which emphasizes the ineffectiveness of antivenom against the venom of given snake species leading to long-term complications.

Case Report: Delayed Diffuse Alveolar Hemorrhage in Echis sochureki Envenoming, Jodhpur, India

Snakebite envenoming is a common occupational hazard in the tropics. Venom-induced consumption coagulopathy and acute kidney injury are the most frequently encountered complications of viper bites. Diffuse alveolar hemorrhage (DAH) is an unusual presentation reported rarely in the literature. Our case report highlights the uncommon presentation of delayed pulmonary hemorrhage after snakebite envenoming. A 40-year-old healthy man presented to our emergency department after 6 hours of Echis sochureki (a saw-scaled viper subspecies) bite. He had abnormal coagulation parameters and thrombocytopenia with no signs of acute kidney injury. Transfusion protocols were initiated because of active bleeding and a rapid decrease in hemoglobin levels over next few days. Around day 10, his coagulation profile and hemoglobin were corrected, but he developed hemoptysis with rapidly progressive respiratory distress. Computed tomography of the chest was suggestive of DAH and the patient was started on plasma exchange with pulse methylprednisolone. After the initial worsening, he had rapid symptomatic improvement and radiological resolution. The patient had persistent hypofibrinogenemia, which resolved, and was discharged and remained healthy at the 60-day follow-up. This case highlights a presentation with an initial phase of venom-induced consumption coagulopathy followed by delayed DAH in saw-scaled viper envenoming that was treated successfully with immunosuppressants and plasma exchange.

A simple mortality risk prediction score for viper envenoming in India (VENOMS): A model development and validation study

BACKGROUND

Snakebite is a neglected problem with a high mortality in India. There are no simple clinical prognostic tools which can predict mortality in viper envenomings. We aimed to develop and validate a mortality-risk prediction score for patients of viper envenoming from Southern India.

METHODS

We used clinical predictors from a prospective cohort of 248 patients with syndromic diagnosis of viper envenoming and had a positive 20-minute whole blood clotting test (WBCT 20) from a tertiary-care hospital in Puducherry, India. We applied multivariable logistic regression with backward elimination approach. External validation of this score was done among 140 patients from the same centre and its performance was assessed with concordance statistic and calibration plots.

FINDINGS

The final model termed VENOMS from the term "Viper ENvenOming Mortality Score included 7 admission clinical parameters (recorded in the first 48 hours after bite): presence of overt bleeding manifestations, presence of capillary leak syndrome, haemoglobin <10 g/dL, bite to antivenom administration time > 6.5 h, systolic blood pressure < 100 mm Hg, urine output <20 mL/h in 24 h and female gender. The lowest possible VENOMS score of 0 predicted an in-hospital mortality risk of 0.06% while highest score of 12 predicted a mortality of 99.1%. The model had a concordance statistic of 0·86 (95% CI 0·79-0·94) in the validation cohort. Calibration plots indicated good agreement of predicted and observed outcomes.

CONCLUSIONS

The VENOMS score is a good predictor of the mortality in viper envenoming in southern India where Russell's viper envenoming burden is high. The score may have potential applications in triaging patients and guiding management after further validation.