Frequent and potentially fatal envenoming by hump-nosed pit vipers (Hypnale hypnale and H. nepa) in Sri Lanka: lack of effective antivenom

In a prospective study of snake bites involving 10 hospitals in Sri Lanka, 302 (35%) of 860 patients with bites by identified snakes proved to have been bitten by hump-nosed pit vipers (301 by Hypnole hypnole and 1 by H. nepa). Most victims were mates aged between 11 years and 50 years who had been bitten on their feet or ankles white walking at night close to their homes. There was local. swelling in 276 (91%) and Local necrosis in 48 (16%). Eleven (4%) required amputation of fingers or toes and 12 (4%) received skin grafts. In 117 patients (39%) blood incoagulability was first detected between 15 min and 48h after the bite, and in 116 of them this was present on admission to hospital. Spontaneous systemic bleeding was observed in 55 patients (18%). Acute renal failure developed in 10%, five of whom died to give an overall case fatality rate of 1.7%. Thus, bites by hump-nosed pit vipers can cause debilitating Local and fatal systemic envenoming. In Sri Lanka and southwestern India where bites by these snakes are common, the only available antivenoms (raised against cobra, krait, Russell's viper and saw-scaled viper venoms) are ineffective and carry a high risk of reactions. Crown Copyright (C) 2008 Published by Elsevier Ltd on behalf of Royal Society of Tropical. Medicine and Hygiene. All rights reserved.