Intestinal histopathology and in situ postures of Gymnophalloides seoi in experimentally infected mice

Abstract

The intestinal histopathology and in situ postures of Gymnophalloides seoi (Digenea: Gymnophallidae) were studied using C3H/HeN and C57BL/6 mice as experimental hosts; the effects of immunosuppression were also observed. The metacercariae isolated from naturally infected oysters, 300 or 1,000 in number, were infected orally to each mouse, and the mice were killed at days 3-21 post-infection (PI). In immunocompetent (IC) mice, only a small number of flukes were found in the mucosa of the duodenum and jejunum during days 3-7 PI, with their large oral suckers pinching and sucking the root of villi. The intestinal mucosa showed mild villous atrophy, crypt hyperplasia, and inflammations in the villous stroma and crypt, with remarkable goblet cell hyperplasia. These mucosal changes were almost restored after days 14-21 PI. In immunosuppressed (IS) mice, displacement as well as complete loss of villi adjacent to the flukes was frequently encountered, otherwise the histopathology was generally mild, with minimal goblet cell hyperplasia. In these mice, numerous flukes were found, and it seemed that they were actively moving and rotating in situ. Several flukes were found to have invaded into the submucosa, almost facing the serosa. These results indicate that in IC mice the intestinal histopathology caused by G. seoi is generally mild, and the flukes do not penetrate beyond the mucosa, however, in IS mice, the flukes can cause severe destruction of neighboring villi, and some of them invade into the submucosa.

Foodborne Intestinal Flukes in Southeast Asia

“…In experimental rodents this was evidenced [164,322]. However, acute pancreatitis was diagnosed in 1 patient [148], and diabetes mellitus was accompanied in 2 patients [324].…”

“…The histopathological changes were generally not so severe, and the mucosal integrity was restored around day 14-21 post-infection [322]. In immunocompetent mice, the worms did not invade the submucosal layer; however, in immunosuppressed mice, worms invaded the submucosa [322]. In a colon cancer patient who received anti-cancer chemotherapy, a G. seoi worm was found to have penetrated into the colonic lymphoid tissue [323].…”

“…The infected intestinal mucosa showed villous atrophy and crypt hyperplasia, with inflammatory reactions in the villous stroma and the crypt [4,322]. The histopathological changes were generally not so severe, and the mucosal integrity was restored around day 14-21 post-infection [322]. In immunocompetent mice, the worms did not invade the submucosal layer; however, in immunosuppressed mice, worms invaded the submucosa [322].…”

“…It was observed in mice, though they are not a good host, that G. seoi parasitizes the small intestine, chiefly the duodenum and jejunum, pinching and sucking the intestinal villi with their oral suckers [322]. The infected intestinal mucosa showed villous atrophy and crypt hyperplasia, with inflammatory reactions in the villous stroma and the crypt [4,322].…”

“…In a colon cancer patient who received anti-cancer chemotherapy, a G. seoi worm was found to have penetrated into the colonic lymphoid tissue [323]. Mechanical irritation and antigenic stimulation by the flukes are considered to be important in the pathogenicity [4,322].…”