Abstract
BackgroundEnvenoming by south Asian hump-nosed pit vipers (Genus: Hypnale) is a significant health issue in Sri Lanka and in peninsular India. Bites by these snakes frequently lead to local envenoming, coagulopathy and acute renal failure even resulting in death. Recently the genus was revised and the existence of three species viz H. hypnale, H. nepa and H. zara were recognized. There is, however, a paucity of information on the toxicity of the venoms of these species. Hence, we compared the toxic effects of the three Hypnale venoms using BALB/c mice.FindingsIntraperitoneal median lethal doses (LD50) for H. hypnale, H. zara and H. nepa venoms were 1.6, 6.0 and 9.5 μg protein/g respectively. Minimum haemorrhagic doses for venoms of H. hypnale, H. zara and H. nepa were 3.4, 11.0 and 16.6 μg protein/mouse respectively. The minimum necrotic doses for the same venoms were 15.0, 55.1 and 68.2 μg protein/mouse respectively. Severe congestion and petecheal haemorrhages were observed in lungs, kidneys, liver and the alimentary tract. Histopathogical examination of kidneys revealed proximal tubular cell injury and acute tubular necrosis with intact basement membrane indicating possible direct nephrotoxicity. Hypnale venoms caused pulmonary oedema, hepatocellular degeneration and necrosis, focal neuronal degeneration in brain and extramedullary haemopoiesis in spleen. H. hypnale venom caused all above histopathological alterations at lower doses compared to the other two.ConclusionHypnale venoms cause similar pathological changes with marked differences in the severity of the toxic effects in vivo. Therefore, differences in the severity of the clinical manifestations could possibly be seen among bite victims of the three Hypnale species.
Highlights
Envenoming by south Asian hump-nosed pit vipers (Genus: Hypnale) is a significant health issue in Sri Lanka and in peninsular India
Materials and methods Venom collection, preparation and storage The specimens of Hypnale species identified using keys described in Maduwage et al [4] were used for venom collection.Venom was collected from the following: H. hypnale, 6 specimens from Galle (06°03’N, 80°12’ E, elevation: 15 m) and 2 specimens from Peradeniya(07°15’N, 80°36’ E, elevation: 465 m), H. nepa (4 specimens) from Agrapathana (06°50’N, 80°40’ E, elevation: 1665 m) and H. zara (4 specimens) from Kottawa (06°06’N, 80°20’ E, elevation: 25 m)
Liver, lung, brain, spleen and intestine were similar with all three Hypnale venoms.The minimum dose of each Hypnale venom that led to each histopathological change differed drastically (Table 2)
Summary
Envenoming by south Asian hump-nosed pit vipers (Genus: Hypnale) is a significant health issue in Sri Lanka and in peninsular India. Bites by these snakes frequently lead to local envenoming, coagulopathy and acute renal failure even resulting in death. The genus was revised and the existence of three species viz H. hypnale, H. nepa and H. zara were recognized. There is, a paucity of information on the toxicity of the venoms of these species. We compared the toxic effects of the three Hypnale venoms using BALB/c mice
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