Hemorrhagic syndrome induced by caterpillars. Clinical and experimental studies. Review

Patients affected with the hemorrhagic syndrome caused by contact with caterpillars of the Lonomia genus show digestive, pulmonary and intraperitoneal bleeding in combination with hematomas and echymosis. Hematuria is also frequently seen. Blood coagulation tests show prolongation of PT, aPTT and ThT. There is a decrease of Fg, FV, FXIII, Pg and alpha 2AP. Factor VIII and FvW are increased while the platelet count is unaffected. FDP's are increased and D-dimers are present in most cases. Treatment with whole blood or fresh frozen plasma worsens the clinical picture causing a severe drop in the platelet count often leading to renal failure and death. However, if antifibrinolytics, either alone or in combination with cryoprecipitate or purified fibrinogen, are administered, no change in the platelet count can be detected and the patients recover rapidly. It is concluded that this syndrome is caused by a mild disseminated intravascular coagulation (DIC) in combination with a hyperfibrinolytic state; the former being partially obscured by the latter, that manifests on administration of whole blood or fresh frozen plasma. Activators of FII, FV and Pg, and compounds showing FXa, plasmin and kallikrein-like activities have been identified in the Lonomia achelous venom. Proteases capable of degrading FXIII and extracellular matrix protein and an inhibitor of FV have also been isolated from these species. In Lonomia oblique, activators of FII and FX and an enzyme with phospholipase-like activity have been identified. In rabbits, subcutaneous injection of crude extract and one of the chromatographically purified fractions of Lonomia achelous venom causes a decrease of Fg, Pg and FXIII. Intravenous administration of the same fraction causes lysis of preformed thrombus with decrease of Fg, Pg and FXIII in combination with inhibition of thrombus growth. It should be noted that, under the same conditions, injection of Lonomia obliqua prothrombin activator causes a DIC.