Case Report: Symptoms and Prognosis of Trimeresurus gracilis Envenomation

Trimeresurus gracilis is a pit viper inhabiting the high mountains of Taiwan. No specific antivenom against T. gracilis is available, and we did not find any prior published case reports on its clinical envenomation. We present two patients with T. gracilis envenomation who were both bitten on the index finger and were administered bivalent hemotoxic antivenom against Trimeresurus stejnegeri and Protobothrops mucrosquamatus. In case 1, the patient was administered seven vials of antivenom within 2 days of envenomation. She received surgical intervention on day 26 and recovered from the wound 3 months after envenomation, but her left index finger was slightly and irreversibly bent. In case 2, the patient was administered 12 vials of antivenom within 10 hours after envenomation, received surgical intervention on day 1, and underwent debridement and reconstruction surgery on day 7 after envenomation. The wounds healed 1.5 months after envenomation, and no deformity occurred. Laboratory data showed elevated D-dimer levels and prothrombin times. The cross-neutralizing ability of bivalent hemotoxic antivenom against T. stejnegeri and P. mucrosquamatus appeared insufficient to treat the local effects of T. gracilis envenomation. The deformity of the finger of the patient in case 1 might have been caused by the lower dose, later administration of antivenins, and a delay in the necessary surgery.