Host-parasite interface of fish acanthocephalans. I. Acanthocephalus anguillae (Palaeacanthocephala) in naturally infected fishes: LM and TEM investigations

Abstract

Nine species of freshwater fish from Ruhrlake (FRG) were investigated for infection with Acanthocephalus anguillae over 2 yr. Prevalence rates of infected fish did not depend on season and were as follows: Leuciscus cephalus 84%, Tinca tinca 44%, Abramis brama 34%, Anguilla anguilla 30%, Rutilus rutilus 16%, Alburnus alburnus 15%. Mean intensities ranged from 1 to 7 worms per fish. Chub was the major host in terms of both prevalence and intensity of infection. In chub, tench, eel, dace and bleak the worms penetrated the intestinal wall by their presoma up to the muscularis or even perforated it completely. The hosts' inflammatory tissue consisted of 3 zones. The first layer, of necrotic cells and degranulated granulocytes, was found adjacent to the surface of the parasite. This necrotic zone gradually passed over to a second layer of mostly intact eosinophilic and heterophilic granulocytes and fibroblasts. The third and outermost layer consisted of collagenous fibers and a few fibroblasts and granulocytes.