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Snakebite-associated acute kidney injury (AKI) poses a significant health burden in the South Asia region, resulting in considerable morbidity and mortality. Multiple factors contribute to the pathogenesis of AKI following snakebites, including hypotension, intravascular haemolysis, disseminated intravascular coagulation, rhabdomyolysis, thrombotic microangiopathy (TMA) and direct nephrotoxicity. Clinical features manifest as anuria, oliguria, haematuria, abdominal pain and hypertension. Diagnosis is supported by elevated serum creatinine levels and urine output monitoring. Renal histology studies revealed a spectrum of lesions, including acute tubular necrosis, renal cortical necrosis, glomerulonephritis and TMA. Management strategies centre around timely administration of antivenom, fluid and electrolyte balance and dialysis to improve renal outcomes. While dialysis has demonstrated efficacy in reducing AKI-related mortality rates, the use of fresh frozen plasma and therapeutic plasma exchange may be the subject of some controversy. Understanding the pathophysiological link between coagulopathy, TMA and AKI is important for tailoring effective treatment approaches. Species-specific randomized controlled trials are imperative to evaluate targeted interventions. In tackling the complexities of snakebite-associated AKI and chronic kidney disease, a multidisciplinary approach integrating clinical management with rigorous research efforts is essential. This collaborative endeavour aims to confront the challenges posed by these conditions and improve patient outcomes in the affected regions., (© The Author(s) 2024. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.)

Haemotoxicity is the most common complication of systemic envenoming following snakebite, leading to diverse clinical syndromes ranging from haemorrhagic to prothrombotic manifestations. Key haematological abnormalities include platelet dysfunction, venom-induced consumption coagulopathy, anticoagulant coagulopathy and organ-threatening thrombotic microangiopathy. Diagnostic methods include the bedside whole blood clotting test, laboratory coagulation screening and other advanced methods such as thromboelastogram and clot strength analysis. The primary management strategies are venom neutralisation with antivenom and correction of coagulopathy with blood component transfusions, while options such as plasma exchange are utilised in certain cases. Recent advancements in understanding the pathogenesis of haemotoxicity have facilitated the development of new diagnostic and treatment modalities. This review summarises current knowledge on the pathogenesis, diagnosis, clinical and laboratory manifestations and treatment of the haematological effects of snake envenoming. Furthermore, it highlights important challenges concerning diagnosis and management. Addressing these challenges is crucial for achieving the WHO's goal of reducing deaths and disabilities caused by snakebites by 2030., (© The Author(s) 2024. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.)

Inadequate effectiveness of Indian antivenoms in treating envenomation caused by the Spectacled Cobra/Indian Cobra ( Naja naja ) in Sri Lanka has been attributed to geographical variations in the venom composition. This study investigated the de novo venom-gland transcriptomics and venom proteomics of the Sri Lankan N. naja (NN-SL) to elucidate its toxin gene diversity and venom variability. The neutralization efficacy of a commonly used Indian antivenom product in Sri Lanka was examined against the lethality induced by NN-SL venom in mice. The transcriptomic study revealed high expression of 22 toxin genes families in NN-SL, constituting 46.55% of total transcript abundance. Three-finger toxins (3FTX) were the most diversely and abundantly expressed (87.54% of toxin gene expression), consistent with the dominance of 3FTX in the venom proteome (72.19% of total venom proteins). The 3FTX were predominantly S-type cytotoxins/cardiotoxins (CTX) and α-neurotoxins of long-chain or short-chain subtypes (α-NTX). CTX and α-NTX are implicated in local tissue necrosis and fatal neuromuscular paralysis, respectively, in envenomation caused by NN-SL. Intra-species variations in the toxin gene sequences and expression levels were apparent between NN-SL and other geographical specimens of N. naja , suggesting potential antigenic diversity that impacts antivenom effectiveness. This was demonstrated by limited potency (0.74 mg venom/ml antivenom) of the Indian polyvalent antivenom (VPAV) in neutralizing the NN-SL venom. A pan-regional antivenom with improved efficacy to treat N. naja envenomation is needed.

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 A 2 s, 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., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. MH and AGH are members of the African Snakebite Research Group (ASRG) project and the Scientific Research Partnership for Neglected Tropical Snakebite (SRPNTS) that are supported by NIHR(UK) and DfID (UK) respectively., (© 2021 The Authors.)

Background: The western Russell's viper ( Daboia russelii ) is widely distributed in South Asia, and geographical venom variation is anticipated among distant populations. Antivenoms used for Russell's viper envenomation are, however, raised typically against snakes from Southern India. The present study investigated and compared the venom proteomes of D. russelii from Sri Lanka (DrSL) and India (DrI), the immunorecognition of Indian VINS Polyvalent Antivenom (VPAV) and its efficacy in neutralizing the venom toxicity., Methods: The venoms of DrSL and DrI were decomplexed with C 18 high-performance liquid chromatography and SDS-polyacrylamide gel electrophoresis under reducing conditions. The proteins fractionated were identified through nano-ESI-liquid chromatography-tandem mass spectrometry (LCMS/MS). The immunological studies were conducted with enzyme-linked immunosorbent assay. The neutralization of the venom procoagulant effect was evaluated in citrated human plasma. The neutralization of the venom lethality was assessed in vivo in mice adopting the WHO protocol., Results: DrSL and DrI venom proteomes showed comparable major protein families, with phospholipases A 2 (PLA 2 ) being the most abundant (> 60% of total venom proteins) and diverse (six protein forms identified). Both venoms were highly procoagulant and lethal (intravenous median lethal dose in mice, LD 50 = 0.24 and 0.32 µg/g, for DrSL and DrI, respectively), while lacking hemorrhagic and anticoagulant activities. VPAV was immunoreactive toward DrSL and DrI venoms, indicating conserved protein antigenicity in the venoms. The high molecular weight venom proteins were, however, more effectively immunorecognized than small ones. VPAV was able to neutralize the coagulopathic and lethal effects of the venoms moderately., Conclusion: Considering that a large amount of venom can be injected by Russell's viper during envenomation, the potency of antivenom can be further improved for optimal neutralization and effective treatment. Region-specific venoms and key toxins may be incorporated into the immunization procedure during antivenom production., Competing Interests: Competing interests: The authors declare that they have no competing interests.

Background: Fixed drug combination of isoniazid and rifampicin is a rare cause of poisoning even in endemic countries for tuberculosis infection. Severe poisoning can cause severe morbidity and mortality if not treated promptly. Though intravenous pyridoxine is the preferred antidote for severe standard isoniazid poisoning it is not freely available even in best of care centers. We describe a case of severe poisoning with fixed drug combination of isoniazid and rifampicin successfully managed with oral pyridoxine at national hospital of Sri Lanka., Case Presentation: A 22 year old, Sri Lankan female presented to a local hospital 1 h after self-ingestion of 28 tablets of fixed drug combination of isoniazid and rifampicin which contained 4.2 g of standard isoniazid and 7.2 g of rifampicin. One and half hours after ingestion she developed generalized tonic-clonic seizure with loss of consciousness. She was given intravenous diazepam 5 mg immediately and transferred to national hospital of Sri Lanka, for further care. Upon arrival to tertiary care hospital in 3.5 h of poisoning she had persistent vomiting, dizziness and headache. On examination, she was drowsy but arousable, orange-red discoloration of the body was noted even with the dark skin complexion. She also had orange-red colour urine and vomitus. Pulse rate was 104 beats/min, blood pressure 130/80 mmHg, respiratory rate was 20 breaths/min. The arterial blood gas analysis revealed compensated metabolic acidosis and mildly elevated lactic acid level. Considering the clinical presentation with neurological toxicity and the large amount of isoniazid dose ingested, crushed oral tablets of pyridoxine 4.2 g (equal to standard isoniazid dose ingested) administered immediately via a nasogastric tube since intravenous preparation was not available in the hospital. Simultaneously forced diuresis using intravenous 0.9% saline was commenced in order to enhance excretion of toxic metabolites via kidneys. She had no recurrence of seizures but had acute liver injury subsequently which gradually improved with supportive care. Her liver functions found to be completely normal 1 week after the discharge., Conclusions: Poisoning with fixed drug combination of isoniazid and rifampicin tablets is rare but can cause severe morbidity and mortality if not treated promptly. Oral pyridoxine can substitute for intravenous pyridoxine with almost similar efficacy at a low cost in managing patients with acute severe standard isoniazid poisoning in resource poor setting.

Unlabelled: The venom proteome (venomics) of the Sri Lankan Daboia russelii was elucidated using 1D SDS PAGE nano-ESI-LCMS/MS shotgun proteomics. A total of 41 different venom proteins belonging to 11 different protein families were identified. The four main protein families are phospholipase A2 (PLA2, 35.0%), snaclec (SCL, 22.4%, mainly platelet aggregation inhibitors), snake venom serine proteinase (SVSP, 16.0%, mainly Factor V activating enzyme) and snake venom metalloproteinase (SVMP, 6.9%, mainly heavy chain of Factor X activating enzyme). Other protein families that account for more than 1% of the venom protein include l-amino acid oxidase (LAAO, 5.2%), Kunitz-type serine proteinase inhibitor (KSPI, 4.6%), venom nerve growth factor (VNGF. 3.5%), 5'-nucleotidase (5'NUC, 3.0%), cysteine-rich secretory protein (CRISP, 2.0%) and phosphodiesterase (PDE, 1.3%). The venom proteome is consistent with the enzymatic and toxic activities of the venom, and it correlates with the clinical manifestations of Sri Lankan D. russelii envenomation which include hemorrhage, coagulopathy, renal failure, neuro-myotoxicity and intravascular hemolysis. The venom exhibited remarkable presypnatic neurotoxicity presumably due to the action of basic PLA2 in high abundance (35.0%). Besides, SCLs, Factor X activating enzymes (SVMPs), SVSPs, and LAAOs are potential hemotoxins (50.5%), contributing to coagulopathy and hemorrhagic syndrome in Sri Lankan D. russelii envenomation., Significance: The study demonstrated the proteomic profile of the Sri Lankan Russell's viper venom, unraveling its complex composition of toxins and correlations with major toxic activities. The types, numbers, and relative abundances of toxins were reported. The venom content was dominated by the neurotoxic basic phospholipases A2 (>30% of total protein abundance) and several hemotoxic or coagulopathic protein families (approximately 50% in total). The proteome correlates with the functional and toxinological characterizations of the venom, and reflects the pathophysiological effects of envenomation by the Sri Lankan Russell's viper. The venom proteomics may serve to propel the understanding on pathogenesis and treatment strategy for envenomation by this viper in Sri Lanka. The enriched database contributed by the proteomic findings will be useful for comparing venom variations among Russell's vipers from different geographical areas., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Russell's viper envenoming is a major problem in South Asia and causes venom induced consumption coagulopathy. This study aimed to investigate the kinetics and dynamics of venom and clotting function in Russell's viper envenoming., Methodology/principal Findings: In a prospective cohort of 146 patients with Russell's viper envenoming, we measured venom concentrations, international normalised ratio [INR], prothrombin time (PT), activated partial thromboplastin time (aPTT), coagulation factors I, II, V, VII, VIII, IX and X, and von Willebrand factor antigen. The median age was 39 y (16-82 y) and 111 were male. The median peak INR was 6.8 (interquartile range [IQR]: 3.7 to >13), associated with low fibrinogen [median,<0.01 g/L; IQR: <0.01-0.9 g/L), low factor V levels [median,<5%; IQR: <5-4%], low factor VIII levels [median,40%; IQR: 12-79%] and low factor X levels [median, 48%; IQR: 29-67%]. There were smaller reductions in factors II, IX and VII over time. All factors recovered over 48 h post-antivenom. The median INR remained >3 at 6 h post-antivenom but had reduced to <2, by 24 h. The aPTT had also returned to close to normal (<50 sec) at 24 h. Factor VII, VIII and IX levels were unusually high pre-antivenom, median peak concentrations of 393%, 307% and 468% respectively. Pre-antivenom venom concentrations and the INR (r = 0.20, p = 0.02) and aPTT (r = 0.19, p = 0.03) were correlated (non-parametric Spearman analysis)., Conclusions: Russell's viper coagulopathy results in prolonged aPTT, INR, low fibrinogen, factors V, VIII and X which recover over 48 h. Severity of clotting abnormalities was associated with venom concentrations.

Russell's viper (RV) envenomation causes local effects, coagulopathy, thrombosis, rhabdomyolysis, acute kidney injury, and neurological manifestations. Although coagulopathy and endothelial destruction causing local and mucosal surface bleeding is known, isolated severe pulmonary hemorrhage is not commonly reported. We report a previously healthy 18-year-old male who had bilateral severe pulmonary hemorrhages, which resulted in a fatal outcome following RV bite. This diagnosis was supported by persistent alveolar shadows, with minimum improvement despite hemodialysis without heparin, mixed acidosis and endotracheal tube bleeding. Other bleeding manifestations were absent. Polyvalent antivenom was administered in lieu of prolonged whole blood clotting time. Thrombocytopenia and mildly deranged clotting parameters were noted. Pulmonary hemorrhages were significant enough to require transfusion. This case highlights the importance of suspecting pulmonary hemorrhages in patients with alveolar shadows and desaturation following RV bite despite the absence of other bleeding manifestations in light of failure of optimum therapy including hemodialysis.

The hump-nosed pit viper, Hypanle hypnale, contributes to snakebite mortality and morbidity in Sri Lanka. Studies showed that the venom is hemotoxic and nephrotoxic, with some biochemical and antigenic properties similar to the venom of Calloselasma rhodostoma (Malayan pit viper). To further characterize the complexity composition of the venom, we investigated the proteome of a pooled venom sample from >10 Sri Lankan H. hypnale with reverse-phase high performance liquid chromatography (rp-HPLC), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and peptide sequencing (tandem mass-spectrometry and/or N-terminal sequencing). The findings ascertained that two phospholipase A2 subtypes (E6-PLA2, W6-PLA2) dominate the toxin composition by 40.1%, followed by snake venom metalloproteases (36.9%), l-amino acid oxidase (11.9%), C-type lectins (5.5%), serine proteases (3.3%) and others (2.3%). The presence of the major toxins correlates with the venom's major pathogenic effects, indicating these to be the principal target toxins for antivenom neutralization. This study supports the previous finding of PLA2 dominance in the venom but diverges from the view that H. hypnale venom has low expression of large enzymatic toxins. The knowledge of the composition and abundance of toxins is essential to elucidate the pathophysiology of H. hypnale envenomation and to optimize antivenom formulation in the future., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: Venom recurrence or persistence in the circulation after antivenom treatment has been documented many times in viper envenoming. However, it has not been associated with clinical recurrence for many snakes, including Russell's viper (Daboia spp.). We compare the recovery of coagulopathy to the recurrence or persistence of venom in patients with Russell's viper envenoming., Methodology/principal Findings: The study included patients with Russell's viper (D. russelii) envenoming presenting over a 30 month period who had Russell's viper venom detected by enzyme immunoassay. Demographics, information on the snake bite, and clinical effects were collected for all patients. All patients had serum collected for venom specific enzyme immunoassay and citrate plasma to measure fibrinogen levels and prothrombin time (international normalised ratio; INR). Patients with venom recurrence/persistence were compared to those with no detectable recurrence of venom. There were 55 patients with confirmed Russell's viper envenoming and coagulopathy with low fibrinogen concentrations: 31 with venom recurrence/persistence, and 24 with no venom detected post-antivenom. Fibrinogen concentrations increased and INR decreased after antivenom in both the recurrence and non-recurrence patients. Clinical features, laboratory parameters, antivenom dose and length of hospital were similar for both groups. Pre-antivenom venom concentrations were higher in patients with venom recurrence/persistence with a median venom concentration of 385 ng/mL (16-1521 ng/mL) compared to 128 ng/mL (14-1492 ng/mL; p = 0.008)., Conclusion: Recurrence of Russell's viper venom was not associated with a recurrence of coagulopathy and length of hospital stay. Further work is required to determine if the detection of venom recurrence is due to the venom specific enzyme immunoassay detecting both venom-antivenom complexes as well as free venom.

The knowledge of venom pharmacokinetics is essential to improve the understanding of envenomation pathophysiology. Using a double-sandwich ELISA, this study investigated the pharmacokinetics of the venom of hump-nosed pit viper (Hypnale hypnale) following intravenous and intramuscular injections into rabbits. The pharmacokinetics of the venom injected intravenously fitted a three-compartment model. There is a rapid (t1/2π = 0.4 h) and a slow (t1/2α = 0.8 h) distribution phase, followed by a long elimination phase (t1/2β = 19.3 h) with a systemic clearance of 6.8 mL h(-1) kg(-1), consistent with the prolonged abnormal hemostasis reported in H. hypnale envenomation. On intramuscular route, multiple peak concentrations observed in the beginning implied a more complex venom absorption and/or distribution pattern. The terminal half-life, volume of distribution by area and systemic clearance of the venom injected intramuscularly were nevertheless not significantly different (p > 0.05) from that of the venom injected intravenously. The intramuscular bioavailability was exceptionally low (Fi.m. = 4%), accountable for the highly varied median lethal doses between intravenous and intramuscular envenomations in animals. The findings indicate that the intramuscular route of administration does not significantly alter the pharmacokinetics of H. hypnale venom although it significantly reduces the systemic bioavailability of the venom., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Context: Limited information exists on the coagulopathy caused by hump-nosed pit viper (Hypnale hypnale) envenoming., Objectives: This study aimed to characterise the coagulopathy in hump-nosed pit viper bites by measuring laboratory clotting times and factor studies., Materials and Methods: Cases of hump-nosed pit viper envenoming were included from a prospective cohort study of Sri Lankan snake-bite patients. Patient age, sex, snake identification, time of bite and clinical effects were recorded. Patients did not receive anti-venom because no specific anti-venom to hump-nosed vipers exists. All patients received supportive care and serial 20-min whole blood clotting tests (WBCT20). The prothrombin time (PT), international normalised ratio (INR), activated partial thromboplastin time (aPTT), coagulation factors I, II, V, VII, VIII, IX and X, von Willebrand factor (vWF) antigen and D-Dimer concentrations were measured. The median of highest or lowest test result for each patient was reported with interquartile range (IQR). Results. There were 80 hump-nosed pit viper bites, median age was 37 years (IQR: 26-51 years) and 48 were male. The WBCT20 was positive in one patient. The median highest INR was 1.9 (1.5-2.2; Range: 1.3 to > 12) and median highest aPTT was 54 s (46-72 s; Range: 35-170 s). There was low fibrinogen [median: 1.3 g/L;1, -1.8 g/L; Range: < 0.2-2.9], low factor VIII levels [median: 23%; 16-37%] and low factor V levels [median: 43%; 23-74%]. D-Dimer concentrations [median: 3.4 mg/L; 2-7.4 mg/L] were slightly elevated. Factors II, VII and X and vWF antigen concentrations were normal., Discussion and Conclusions: Hump-nosed pit viper bites result in a mild coagulopathy which is usually not detected by a WBCT20. It is characterised by mild elevation of INR, low fibrinogen and Factors V and VIII which may be consistent with the venom containing a thrombin-like enzyme.

Background: Echis carinatus (Saw scaled viper {SSV}) is a venomous snake found in the parts of Middle East and Central Asia. SSV envenoming is characterized by local swelling and coagulopathy. Various bleeding manifestations are commonly seen with SSV envenoming. In contrast to other part of Asia, saw scale viper envenoming has not been reported to cause life threatening haemorrhagic manifestations in Sri Lanka., Case Presentation: We report a 19 years old healthy boy who developed massive left temporo-parietal intra cerebral haemorrhage following Echis carinatus (Saw scaled viper) bite in Sri Lanka., Conclusion: Although subspecies of SSV in Sri Lanka is regarded as a 'non lethal venomous snake', the occurrence of rare potentially fatal complications such as intracerebral haemorrhage should be considered in their management. This case report is intended to bring the awareness of this fatal complication of SSV envenoming in Sri Lanka.

Russell's viper envenoming is associated with a high incidence of morbidity and mortality. Hypopituitarism following envenoming by Russell's vipers is a well recognized sequel in Burma and parts of India but has been reported only once in Sri Lanka. Hypokalaemia following envenoming by Russell's viper has not been described. Here we describe the association of acute pituitary insufficiency and hypokalaemia following Russell's viper envenoming in Sri Lanka and review the literature in order to understand its pathophysiological basis. A previously healthy 21-year-old man was envenomed by a Russell's viper and treated with antivenom. Ten hours after the bite, he developed persistent hypotension, which responded promptly to intravenous dexamethasone. His hormone profiles were consistent with hypocortisolism secondary to acute pituitary insufficiency. He also developed hypokalaemia. Analysis of urine and serum electrolytes suggested redistribution of potassium in to the cells rather than renal loss. Hypotension and hypoglycaemic coma are life-threatening manifestations of acute pituitary insufficiency. Therefore prompt steroid administration in these setting is life saving. Awareness of these complications among physicians would help to make prompt diagnosis and initiate immediate life saving treatment., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Mice experimentally envenomed with Hypnale hypnale venom (1× and 1.5×LD₅₀) developed acute kidney injury (AKI) principally characterized by raised blood urea and creatinine. Prolonged blood clotting time and hemorrhage in lungs implied bleeding tendency. Pallor noted in most renal cortices was suggestive of renal ischemia secondary to consumptive coagulopathy. Intravenous infusion of Hemato polyvalent antivenom following experimental envenoming effectively prevented death and AKI in all mice, supporting its potential therapeutic use in envenoming cases., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Hump-nosed pit viper (Genus Hypnale) is a medically important venomous snake in Sri Lanka and Southwestern India which causes significant morbidity and mortality. Envenoming of this snake results in hemostastic dysfunction, thrombotic microangiopathy, acute kidney injury and death. This case describes an authenticated first case of ischemic stroke in a 65 year old male following envenoming by H.hypnale in Sri Lanka.

Oxalic acid poisoning is being recognized as an emerging epidemic in the rural communities of Sri Lanka as it is a component of locally produced household laundry detergents. Herein we describe a case of a 32 year old female, presenting after direct ingestion of oxalic acid. She then went on to develop significant metabolic acidosis and acute renal failure, requiring dialysis. Renal biopsy revealed acute tubulointerstitial nephritis associated with diffuse moderate acute tubular damage with refractile crystals in some of the tubules. The patient symptomatically improved with haemodialysis and renal functions subsequently returned to normal.

Envenomation by hump-nosed pit viper (Hypnale hypnale, Hh) in Sri Lanka has caused significant morbidity and mortality, attributed to 35% of total venomous snakebites. In Southwestern India (Kerala), H. hypnale was increasingly identified as a dangerous and common source of envenomation, second to the Russell's viper but ahead of the cobra bites. Unfortunately, there is still no specific antivenom to date. This study aims to investigate the immunological properties of the venom and to assess the feasibility of specific Hh antivenom production as well as the development of a diagnostic assay. Hh venom elicited satisfactory titers of anti-Hh IgG in rabbits after 3rd immunization. The anti-Hh IgG, isolated with caprylic acid precipitation method, was effective in neutralizing the venom lethality (potency=48 LD(50) per ml IgG) as well as its procoagulant, hemorrhagic and necrotic effects, indicating the possibility to produce the specific antivenom using the common immunization regime. Cross-reactivity studies using indirect ELISA showed that anti-Hh IgG cross-reacted extensively with several Asiatic crotalid venoms, particularly that of Calloselasma rhodostoma (73.6%), presumably due to the presence of venom antigens common to both snakes. Levels of immunological cross-reactivity were vastly reduced with double-sandwich ELISA. Further work demonstrated that the assay was able to distinguish and quantify venoms of H. hypnale, Daboia russelii and Echis carinatus sinhaleyus (three common local viperid) used to spike human sera at various concentrations. The assay hence may be a useful investigating tool for diagnosing biting species and studying the time course profile of venom concentrations in blood., (Copyright © 2012 Elsevier B.V. All rights reserved.)