A Study of 225 Malayan Pit Viper Bites in Thailand

This study evaluated factors affecting the severity of bite site necrosis and systemic symptoms resulting from envenomation among patients bitten by Malayan pit vipers (Calloselasma rhodostoma) in Thailand. We studied 145 victims prospectively. An additional 80 medical records were obtained for a retrospective study. Collected data included gender of the victims, anatomic locations of bites, where attacks took place, and predisposing factors and how they might have affected the clinical course. Most patients presented with minimal to moderate symptoms. Only eight patients required surgical wound debridement. None required amputation. However, 27 subjects developed permanently swollen limbs, presumably because of lymphatic or vascular injury. Significant coagulopathies were common (52.48%), and the only two deaths were attributable to intracranial hemorrhage. The improved clinical outcomes in the prospective and retrospective groups, compared with older series, might have been attributable to better public education, improved road infrastructure, and more health care facilities. Less reliance on nonprofessional healers and fewer applications of tourniquets also might have influenced clinical outcomes. Malayan pit viper antivenin, manufactured in Thailand, appears to be effective in reversing dangerous coagulopathies.