Acanthocephalus anguillae in Intra- and Extraintestinal Positions in Experimentally Infected Juveniles of Goldfish and Carp and in Sticklebacks

Abstract

In the laboratory fingerlings of goldfish and carp as well as adult sticklebacks (Gasterosteus aculeatus) were infected with the palaeacanthocephalan Acanthocephalus anguillae. The fish were killed from 5 to 90 days later. In goldfish, worms began perforating the intestinal muscularis within the first 5 days postinfection (DPI). From about 50 days they were also found in toto inside the peritoneal cavity where they had become covered by a precipitin-like coat. Disintegrating dead worms always were enclosed by a granuloma consisting mainly of macrophages in different maturation stages. In carp intraperitoneal worms were recorded as early as 10 DPI. They provoked a heavy eosinophilic reaction and degenerated within a few days. In stickleback the recovery rates were very low; only 1 worm of 10 DPI was found just penetrating into the peritoneal cavity. The worms did not reproduce in any of the 3 hosts. However, female worms with copulatory caps were found, indicating that they had been inseminated. It is suggested from these results and from the literature that A. anguillae has a low ability to use paratenic hosts in its life cycle.