Helminthiasis, the hypereosinophilic syndrome and endomyocardial fibrosis: some observations and an hypothesis.

It has been shown that chronic African endomyocardial fibrosis (E.m.f.) is most likely the burnt-out phase of parasite-induced hypereosinophilia. It has also been shown that African E.m.f. and Loffler's heart disease are pathologically identical. The mechanism by which these parasites and/or eosinophilia are associated with endomyocardial damage remains, however, unknown. The parasites which have been associated with induction of eosinophilia in E.m.f. include filariasis; trichinosis; ascariasis and hookworm and schistosomiasis. These parasites are known to produce neurologic, cardiac, pneumonic, hepatic and dermal damage during the migration of their larvae; at which time eosinophilia is usually most severe. The tissue damage induced by larval migration of these parasites appears comparable to findings seen in the hypereosinophilic syndrome. The evidence from our observations and this review suggests that the cardiac damage induced by larval migration, like the neurologic, pneumonic and dermal damage, is allergic in nature. Endomyocardial fibrosis has previously been shown to be an allergic heart disease. It appears reasonable to regard African endomyocardial fibrosis as representing the most intense, non-specific cardiac allergic reaction to helminthic larvae.