A nationwide study of Vipera berus bites during one year-epidemiology and morbidity of 231 cases

OBJECTIVES

To describe clinical course, influence of treatment, and epidemiology of Vipera berus envenomation in a defined population, and to compare the results with those of a similar, nationwide study in 1975. Design. Retrospective case review study.

SETTING AND SUBJECTS

Case records regarding all patients treated in Swedish hospitals during 1995 for bites by the common European adder, V. berus, were studied. A severity grading was applied. Possible dropout was fewer than 10 patients.

RESULTS

A total of 231 inpatients were treated for V. berus bites in Sweden in 1995. Children less than 10 years old were overrepresented and there was a slight predominance for males. Maximum severity of envenomation was none in 11%, minor in 47%, moderate in 29%, and severe in 13% of the cases. A few patients with initially minor or moderate symptoms eventually met the criteria of severe envenomation. Less commonly reported features were pulmonary edema, generalized plasma leakage, seizures, deep venous thrombosis, compartment syndrome, numbness and paraesthesia, and myocardial infarction. Treatment included antivenom in 42 patients [ovine Fab in 30 and equine F(ab')2 in 12 cases]. Systemic symptoms resolved during or shortly after the antivenom infusion. Extensive edema involving the trunk occurred in 5% of the cases in 1995, whereas 14% of the patients had extensive swelling in 1975.

CONCLUSIONS

Incidence and other epidemiological data were similar to those 20 years ago, whereas the clinical course was more benign. It seems reasonable to believe that this is due to the introduction of effective antivenoms.