Complete clinical course of envenomation by Protobothrops mangshanensis: delayed coagulopathy and response to Trimeresurus albolabris antivenom

Introduction: Protobothrops mangshanensis, the Mangshan pit viper, is a rare pit viper native to the area surrounding Mount Mang in China’s Hunan province. Toxicity from envenomation is not well characterized. Case details: A 33-year-old male presented to an emergency department (ED) after being bitten on the forearm by his P. mangshanensis. He complained of mild swelling and pain at the bite site. He was admitted for observation and toxicology consultation. Following initially normal coagulation studies including platelets, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and D-dimer, fibrinogen decreased to 121?mg/dL and D-dimer concurrently rose to 377?ng/mL over 24?h. On hospital day 2 fibrinogen stabilized at 109?mg/dL and he was discharged with outpatient laboratory monitoring. Three days later, he returned with bruising to the contralateral arm. Fibrinogen was undetectable (<40?mg/dL) and PT was 14.6?s. He declined admission but returned 2 d later with bruising to the nose. Bloodwork revealed immeasurably prolonged PT, aPTT, and thrombin time, but he eloped. Late that evening he returned and was treated with three vials of Green pit viper (Trimeresurus albolabris) antivenom. Within 24 h coagulopathy improved markedly; at five days, coagulation abnormalities resolved. Discussion: Mangshan pit viper envenomations may cause isolated hemotoxicity, despite molecular studies suggesting additional neurotoxicity and myotoxicity. T. albolabris antivenom appears effective in treating the resultant coagulopathy. Conclusion: We report the natural history of envenomation by the Mangshan pit viper. A delayed coagulopathy, apparently fibrinolytic in nature, is unaccompanied by local tissue destruction and responsive to Green pit viper antivenom.