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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.

BackgroundRussell’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 FindingsIn 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 39y (16–82y) and 111 were male. The median peak INR was 6.8 (interquartile range[IQR]:3.7 to >13), associated with low fibrinogen [median,<0.01g/L;IQR:<0.01–0.9g/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 48h post-antivenom. The median INR remained >3 at 6h post-antivenom but had reduced to <2, by 24h. The aPTT had also returned to close to normal (<50sec) at 24h. 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).ConclusionsRussell’s viper coagulopathy results in prolonged aPTT, INR, low fibrinogen, factors V, VIII and X which recover over 48h. Severity of clotting abnormalities was associated with venom concentrations.

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Abstract: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 A 2 , 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 A 2 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.

BackgroundVenom 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 FindingsThe 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).ConclusionRecurrence 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.

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.