RELATIONSHIP BETWEEN VENOM ANTIGENAEMIA AND SEVERITY OF Bothrops jararaca ENVENOMING IN BRAZIL

FRANÇA, F.O.S.(1,4), BARBARO, K.C.(2), FAN, H.W.(1), CARDOSO, J.L.C.(1), SANO-MARTINS, I.S.(3), TOMY S.C.(3), LOPES, M.H.(4), WARRELL, D.A.(5), THEAKSTON, R.D.G.(6), BUTANTAN INSTITUTE ANTIVENOM STUDY GROUP(1)

(1,7)Hospital Vital Brazil, (2)Lab. Immunopathology, (3,7)Lab. Pathophysiology, Instituto Butantan, São Paulo, Brazil, (4)Department of Infectious and Parasitic Diseases, Faculty of Medicine, University of São Paulo, Brazil, (5)Centre for Tropical Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK, (6)Liverpool School of Tropical Medicine, Liverpool, UK.

A association between the clinical severity of Bothrops jararaca envenoming on admission and serum venom and plasma fibrinogen levels in 137 human snake bite victims admitted to Hospital Vital Brazil, Instituto Butantan, São Paulo less than 48 hours after the bite is reported. Other variables such as age, sex, site of the bite, use of tourniquet and the time between the accident and antivenom therapy, bleeding, the whole blood clotting test (WBTC20) on admission showed no association with either severity or serum venom. Venom antigenaemia was measured using enzyme immunoassay (EIA) before antivenom administration. The mean serum venom level in patients with mild envenoming was significantly lower than in the group with moderate envenoming (p = 0.0007). Patients with levels of plasma fibrinogen > 1.5 g/L had a lower mean admission serum venom level than patients with plasma fibrinogen levels < 1.5 g (p = 0.025). Also, patients admitted with a tourniquet in place had significantly higher fibrinogen levels than those who had had no tourniquet applied (p = 0.002).  The multiple logistic regression model showed that the independent risk factors for severity of Bothrops accidents were bites which occurred at different sites other than leg and forearm, serum venom levels above or equal to 400 ng/ml and the use of a tourniquet. In conclusion, a rapid test to quantify serum venom levels prior to antivenom therapy may contribute to an improvement in the initial evaluation of severity in Bothrops accidents.

CORRESPONDENCE TO:

FRANÇA, F.O.S., Hospital Vital Brazil, Instituto Butantan, Avenida Vital Brasil, 1500, São Paulo, 05503-900, SP, Brasil, Email: fosfranca@uol.com.br