Envenomation by the hump-nosed viper (Hypnale hypnale)

We carried out a prospective clinical study from June to December 1993 at the Base Hospital in Avissawella, Sri Lanka to determine the clinical features of envenomation by the hump-nosed viper (Hypnale hypnale). Sixty-two consecutive adult patients (63% males and 37% females, with a median age of 30 years [age range 13-68 years]) admitted to the medical unit following hump-nosed viper bites were surveyed. Most (85.48%) of the patients were bitten on the feet, while 14.52% of the patients were bitten either on the hands or forearms. Most (61.29%) of the patients were bitten during the evening hours (6:00-10:00 PM). The mean time for admission to the hospital following the bite was 1.5 hr (range 0.25-13 hr). All patients had signs of local envenomation manifested by pain, swelling, and induration at the site of the bite, which was occasionally associated with local hemorrhagic blister formation (11.29%) and regional lymphadenopathy (24.19%). None of the patients had signs of systemic envenomation.