A study on clinical and laboratory features of pit viper envenomation from Central Kerala, India

Background: Snakebite envenomation is an important public health problem faced by the tropical countries with India, the worst affected in terms of mortality and morbidity. In spite of increasing reports of other snake species causing envenomation, the existing research and management strategies including antivenom are still focused on the “Big Four” species- Russel’s viper, saw scaled viper, common krait and spectacled cobra. Pit vipers as a group are being increasingly reported to cause human bites from different parts of the country. Hence, we decided to study the clinico-epidemiology of pit viper bites.Methods: 30 cases of proven pit viper bites who attended our Department during the study period of 18 months were analysed for the epidemiological factors, clinical features and abnormalities in laboratory parameters.Results: Hump nosed pit viper (Hypnale hypnale) was responsible for all the thirty cases. 57% of cases were females. Mean age of victims was 41.8 years. 17 patients had exclusively local envenomation. Ten cases had coagulopathy along with local envenomation. Three patients developed acute kidney injury of whom three underwent dialysis. No mortality was observed in the study. Low fibrinogen levels were observed in all cases with coagulopathy and some had low levels of factor V (70%) and factor VIII (40%).Conclusions: Hump nosed viper bites were observed to be common in this part of the country. Significant envenomation can occur. Further epidemiologic studies involving more centres will be helpful in quantifying the true incidence of bites. Since no specific antivenom is available, further researches in this direction are warranted.

Hump-nosed viper bite: an important but under-recognized cause of systemic envenoming

Hump-nosed viper bites are common in the Indian subcontinent. In the past, hump-nosed vipers (Hypnale species) were considered moderately venomous snakes whose bites result mainly in local envenoming. However, a variety of severe local effects, hemostatic dysfunction, microangiopathic hemolysis, kidney injury and death have been reported following envenoming byHypnale species. We systematically reviewed the medical literature on the epidemiology, toxin profile, diagnosis, and clinical, laboratory and postmortem features of hump-nosed viper envenoming, and highlight the need for development of an effective antivenom.

Hump-nosed viper bite: an important but under-recognized cause of systemic envenoming

Hump-nosed viper bites are common in the Indian subcontinent. In the past, hump-nosed vipers (Hypnale species) were considered moderately venomous snakes whose bites result mainly in local envenoming. However, a variety of severe local effects, hemostatic dysfunction, microangiopathic hemolysis, kidney injury and death have been reported following envenoming byHypnale species. We systematically reviewed the medical literature on the epidemiology, toxin profile, diagnosis, and clinical, laboratory and postmortem features of hump-nosed viper envenoming, and highlight the need for development of an effective antivenom.

Enzymatic and toxinological activities of Hypnale hypnale (hump-nosed pit viper) venom and its fractionation by ion exchange high performance liquid chromatography

Hypnale hypnale (hump-nosed pit viper) has been recently identified as one of the medically important venomous snakes in Sri Lanka and on the southwestern coast of India. The characterization of its venom is essential for understanding the pathophysiology of envenomation and for optimizing its management. In the present study, the biological properties of Hypnale hypnale venom and venom fractions obtained using Resource Q ion exchange chromatography were determined. The venom exhibited toxic activities typical of pit viper venom, comparable to that of its sister taxon, the Malayan pit viper (Calloselasma rhodostoma). Particularly noteworthy were its high activities of thrombin-like enzyme, proteases, phospholipase A2, L-amino acid oxidase and hyaluronidase. The thrombin-like enzyme was mainly acidic and distributed over several chromatography fractions, indicating its existence in multiple isoforms. The hemorrhagic and necrotic activities of the venom were likely associated with the proteolytic enzyme found mainly in the basic fraction. Phospholipase A2 and phosphomonoesterase exist in both acidic and basic isoforms, while L-amino acid oxidase and hyaluronidase are highly acidic. The venom clotting activity on fibrinogens showed distinct species specificity in the following increasing order for clotting time: bovine < rabbit < goat < human < horse < < dog, and was comparable to that of C. rhodostoma venom. Its clot formation on human fibrinogen is gradual and prolonged, a phenomenon suggestive of consumptive coagulopathy as a complication observed clinically. At an intramuscular sublethal dose, the venom did not cause acute kidney injury in a rodent model, contrary to the positive control group treated with Daboia russelii venom. Nephrotoxicity may result from higher venom doses in the context of coagulopathy, as a complication provoked by venom hematoxicity.(AU)