Clinical and epidemiological aspects of the 'urutu' lance-headed viper (Bothrops alternatus) bite in a Brazilian hospital.

Data on 32 cases of Bothrops alternatus (the 'urutu' lance-headed viper) bite admitted to a Brazilian teaching hospital from 1985 to 1992 were retrospectively surveyed. The majority of the bites occurred within the household area, i.e. in the house or its environs (56.3%), in the 15-49 years age group (74.2%), and in the lower limbs (84.3%). The male to female ratio was 1 to 1. 59.4% of the patients were given the antivenom within two hours of the bite. Bites in the household area were commonest in old ladies, whereas all the cases associated with leisure activities, and the majority of the bites associated with labour in the field occurred in men. All patients had local pain and oedema; prolonged clothing time was present in 96.9% of the cases, haemorrhage in 40.6%, blisters in 21.9% and necrosis in 9.4%. A tourniquet was used by 43.8% of the patients. A median of 4 ampoules of antivenom were administered. There was no death in this series. There was no significant trend between increasing age and necrosis, nor between time interval between bite and antivenom administration and occurrence of blisters or necrosis. Presence of blister(s) was associated with necrosis (p = 0.007), but use of a tourniquet, altered clotting time or presence of haemorrhage were not. These findings, compared with those of case series of bites of other species of Bothrops, and contrary to the popular belief, indicate that B. alternatus bite is not always severe, and has even a lower rate of complications.(ABSTRACT TRUNCATED AT 250 WORDS)