Envenomation by Trimeresurus stejnegeri stejnegeri: clinical manifestations, treatment and associated factors for wound necrosis

Trimeresurus stejnegeri stejnegeri bite induces tissue swelling, pain, thrombocytopenia, rhabdomyolysis, and acute renal failure. However, the incidence of coagulopathy, factors associated with wound necrosis, and the appropriate management of this condition have not been well characterized yet. Materials: This study included patients bitten by T. s. stejnegeri that were admitted to the study hospitals from 2001 to 2016. Patient characteristics, laboratory data, and management approaches were compared in victims with and without wound necrosis. Results: A total of 185 patients were evaluated: three patients (1.6%) were asymptomatic; whereas tissue swelling and pain, local ecchymosis, wound necrosis, coagulopathy, thrombocytopenia, rhabdomyolysis, and renal impairment were present in 182, 53, 13, 15, 10, 1, and 3 patients, respectively. One patient died from coagulopathy and hemorrhagic shock. Antivenom was administered to all envenomed patients at a median time of 1.8 h after the bite. The median total dose of antivenom was five vials. Chi-square analysis showed that bitten fingers, using cold packs during first aid, presence of bullae or blisters, lymphangitis or lymphadenitis, local numbness and suspected infection to be significantly associated with wound necrosis. After adjustment using a multivariate logistic regression model, only cold packs as first aid, bulla or blister formation, and wound infection remained significant. Conclusions: The main effects of T. s. stejnegeri envenomation are tissue swelling, pain, and local ecchymosis. We do not recommend the use of cold packs during first aid to reduce wound pain, as this may be a risk factor for wound necrosis. In addition, patients with bulla or blister formation should be carefully examined for subsequent wound necrosis. Antiplatelet use may worsen systemic bleeding. No severe rhabdomyolysis or renal failure was observed in this large case series, we therefore considered that they were not prominent effects of T. s. stejnegeri bite.(AU)

Chicken antibodies against venom proteins of Trimeresurus stejnegeri in Taiwan

The venom of bamboo vipers (Trimeresurus stejnegeri - TS), commonly found in Taiwan, contains deadly hemotoxins that cause severe envenomation. Equine-derived antivenom is a specific treatment against snakebites, but its production costs are high and there are some inevitable side effects. The aim of the present work is to help in the development of an affordable and more endurable therapeutic strategy for snakebites. Methods: T. stejnegeri venom proteins were inactivated by glutaraldehyde in order to immunize hens for polyclonal immunoglobulin (IgY) antibodies production. After IgY binding assays, two antibody libraries were constructed expressing single-chain variable fragment (scFv) antibodies joined by the short or long linker for use in phage display antibody technology. Four rounds of biopanning were carried out. The selected scFv antibodies were then further tested for their binding activities and neutralization assays to TS proteins. Results: Purified IgY from egg yolk showed the specific binding ability to TS proteins. The dimensions of these two libraries contain 2.4 × 107 and 6.8 × 107 antibody clones, respectively. An increase in the titers of eluted phage indicated anti-TS clones remarkably enriched after 2nd panning. The analysis based on the nucleotide sequences of selected scFv clones indicated that seven groups of short linkers and four groups of long linkers were identified. The recombinant scFvs showed significant reactivity to TS venom proteins and a cross-reaction to Trimeresurus mucrosquamatus venom proteins. In in vivo studies, the data demonstrated that anti-TS IgY provided 100% protective effects while combined scFvs augmented partial survival time of mice injected with a lethal amount of TS proteins. Conclusion: Chickens were excellent hosts for the production of neutralization antibodies at low cost. Phage display technology is available for generation of monoclonal antibodies against snake venom proteins. These antibodies could be applied in the development of diagnostic kits or as an alternative for snakebite envenomation treatment in the near future.(AU)

Clinical and laboratory features distinguishing between Deinagkistrodon acutus and Daboia siamensis envenomation

There are 6 species of venomous snakes in Taiwan. Two of them, Deinagkistrodon acutus (D. acutus) and Daboia siamensis (D. siamensis), can cause significant coagulopathy. However, a significant proportion of patients with snakebites cannot identify the correct snake species after envenomation, which hampers the application of antivenom. Hence, the differential diagnosis between the two snakebites by clinical presentations is important. This study aims to compare their clinical and laboratory features for the purpose of differential diagnosis between the two snakebites. Methods: We retrospectively reviewed the medical records of patients who arrived at the emergency department due to D. acutus or D. siamensis envenomation, between 2003 and 2016, in one medical center in eastern Taiwan. Since these snakebites are rare, we also included 3 cases reported from another hospital in central Taiwan. Results: In total, 15 patients bitten by D. acutus and 12 patients by D. siamensis were analyzed. Hemorrhagic bulla formation and the need for surgical intervention only presented for D. acutus envenomation cases (Both 53.3% vs. 0.0%, P= 0.003). As to laboratory features, lower platelet counts (20.0 × 103/µL [interquartile range, 14-66 × 103/µL] vs. 149.0 × 103/µL [102.3-274.3 × 103/µL], P = 0.001), lower D-dimer level (1423.4 µg/L [713.4-4212.3 µg/L] vs. 12,500.0 µg/L [2351.4-200,000 µg/L], P = 0.008), higher proportion of patients with moderate-to-severe thrombocytopenia (platelet count < 100 × 103/µL) (80% vs. 16.7%, odds ratio (OR) = 20.0, 95% CI, 2.77-144.31; P = 0.002), and lower proportion of patients with extremely high D-dimer (> 5000 ng/mL) (16.7% vs. 66.7%, adjusted OR = 0.1 (95% CI, 0.01-0.69; P = 0.036) were found among cases of D. acutus envenomation compared to D. siamensis envenomation. The combination of hemorrhagic bulla, thrombocytopenia, and a lack of extremely high D-dimer had good discriminatory power (area under the curve (AUC) = 0.965; 95% CI, 0.904-1.00) for distinguishing D. acutus from D. siamensis envenomation. Conclusions: The presentation of moderate to severe thrombocytopenia (platelet count < 100 × 103/µL) and hemorrhagic bulla formation may indicate D. acutus envenomation. However, the envenomed patient with extremely high D-dimer levels may indicate a D. siamensis envenomation. These findings may help diagnose and select the right antivenom in patients with unknown snakebites who present significant coagulopathy.(AU)

Deinagkistrodon acutus envenomation: a report of three cases

Background Deinagkistrodon acutus envenomation is associated with severe hematological and wound complications but is rarely described. Case presentation Herein, we report three cases of victims bitten by D. acutus and indicate that rapid-onset severe coagulopathy and thrombocytopenia are distinct features of D. acutus snakebite, which are not observed in other crotaline snakebites (i.e., Trimeresurus stejnegeri and Protobothrops mucrosquamatus) in Taiwan. The toxic effects could occur as early as 2 to 3 h following D. acutus envenomation and persist if the administration of specific antivenom is delayed or even not commenced. Based on our findings, 2 to 4 vials of specific antivenom as the first dose should be administered to victims and repeated at 6 to 8 h intervals if coagulopathy or thrombocytopenia persists. Fresh frozen plasma or platelet replacement is probably safe as an adjunct therapy for D. acutus bite in the presence of venom-induced consumptive coagulopathy. Conclusion Severe coagulopathy and thrombocytopenia could occur as early as 2 to 3 h after D. acutus envenomation. The current recommendation for antivenom is 2 to 4 vials as the first dose and repeated every 6- to 8 h if coagulopathy or thrombocytopenia persists. These cases studied may be helpful to first-line medical personnel in the early diagnosis and management of D. acutus envenomation among other crotaline snakebites in Taiwan.(AU)

Deinagkistrodon acutus envenomation: a report of three cases

Abstract Background Deinagkistrodon acutus envenomation is associated with severe hematological and wound complications but is rarely described. Case presentation Herein, we report three cases of victims bitten by D. acutus and indicate that rapid-onset severe coagulopathy and thrombocytopenia are distinct features of D. acutus snakebite, which are not observed in other crotaline snakebites (i.e., Trimeresurus stejnegeri and Protobothrops mucrosquamatus) in Taiwan. The toxic effects could occur as early as 2 to 3 h following D. acutus envenomation and persist if the administration of specific antivenom is delayed or even not commenced. Based on our findings, 2 to 4 vials of specific antivenom as the first dose should be administered to victims and repeated at 6 to 8 h intervals if coagulopathy or thrombocytopenia persists. Fresh frozen plasma or platelet replacement is probably safe as an adjunct therapy for D. acutus bite in the presence of venom-induced consumptive coagulopathy. Conclusion Severe coagulopathy and thrombocytopenia could occur as early as 2 to 3 h after D. acutus envenomation. The current recommendation for antivenom is 2 to 4 vials as the first dose and repeated every 6 to 8 h if coagulopathy or thrombocytopenia persists. These cases studied may be helpful to first-line medical personnel in the early diagnosis and management of D. acutus envenomation among other crotaline snakebites in Taiwan.