The histopathology of acute and chronic infections of rainbow trout Salmo gairdneri Richardson with eye flukes, Diplostomum spp.

Abstract

A histopathological study was carried out on rainbow trout suffering from acute and chronic diplostomiasis. Clinical signs were few in acutely infected fish but in chronic cases fish were blind, exophthalmic and emaciated. Acute infections resulted in subcapsular cataract formation with varying capsular change. Chronically infected fish frequently showed lens dislocation, capsular rupture or duplication and the formation of Elschnig's pearls and Wedl cells. Phacogenic uveitis was seen in many fish with capsular rupture and retinal detachment frequently occurred as a sequal to vitreous detachment.

Diplostomum spathaceum:effects of temperature and light on cercarial shedding and infection of rainbow trout

“…The digenean trematode Dlplostomum spathaceum is a well-known parasite in fishes where it occurs as metacercaria in the eye lenses of the host and often causes parasitic cataract (Shariff et al 1980). The helminth has been recorded from rainbow trout Oncorhynchus mykiss in a large number of countries (Buchmann et al 1995a), and is still known to occur prevalently in some modern trout farms (Buchmann et al 1995b).…”

Indications of non-specific protective mechanisms in rainbow trout Oncorhynchus mykiss with diplostomosis

“…It is caused by metacercariae of the digenean Diplostomum spathaceum, which establish themselves in the eye lens of fish, which is an immunologically privileged site (Shariff et al 1980). In this respect, D. spathaceum differs from many of the endoparasitic helminths, which evoke an antibody response in infected fish (Molnar & Berzi 1965, Harris 1970, 1972, Harris & Cottrell 1976, Cottrell 1977, McArthur 1978, Wood & Matthews 1987, Szalai et al 1988.…”

Occurrence of Diplostomum pseudospathaceum Niewiadomska, 1984 and D. mergi Dubois, 1932 (Digenea: Diplostomidae) in Danish freshwater snails: ecological and molecular data

“…Eye flukes of the genera Diplostomum von Nordmann, 1832 and Tylodelphys Diesing, 1850 parasitise mainly freshwater fish (Betterton 1974, Sweeting 1974, Shariff et al 1980, Kennedy 1981, Höglund and Thulin 1992, Owen et al 1993, Buchmann and Uldal 1994, Field and Irwin 1995, Larsen et al 2005. The life cycle involves pulmonate snails as first intermediate hosts (infected by sporocysts releasing cercariae), fish as second intermediate hosts (metacercariae in the eyes) and fish-eating birds as final hosts (carrying the adult fluke in the intestine).…”