Hemorrhagic Syndrome Induced by Contact with Caterpillars of the Genus Lonomia (Saturniidae, Hemileucinae)

Abstract

A bleeding syndrome induced by contact with Lonomia achelous caterpillars was first described in Venezuela in 1967. It was reported in the early eighties in North Brazil among rubber latex collectors. From 1989 a very high incidence has been observed in South Brazil due to contact with L. obliqua. Symptoms are similar in all accidents, starting with a burning pain after contact followed by erythema, edema and heat; blisters, headache, nausea, and vomit may also appear. The onset of a hemorrhagic syndrome one to twelve hours later manifests as hematoma throughout the body, epistaxis, bleeding from mucosa and from healing scars, with low plasma fibrinogen concentrations. An intense fibrinolytic activity has been detected in the blood of the patients.Contact of Swiss rats with Lonomia obliqua caterpillars or intradermal injections of Lonomia hair extracts into rats induced blood incoagulability within one to two hours. Studies with these extracts demonstrated a dose-dependent procoagulant activity, higher on rat than on human plasma and potentiated by calcium. On purified fibrinogen, the extracts are weakly active only when calcium is present. The procoagulant activity of the extract was slightly inhibited by heparin and better inhibited by hirudin.The mechanism of the overwhelming fibrinolytic state observed in patients has still to be elucidated since it is not explained by in vitro tests with Lonomia obliqua hair extracts on a chromogenic substrate specific for plasmin and there is hardly any plasminogen activator-like activity in these extracts.