Water-born transmission of Dermocystidtum salmonis in the laboratory

Abstract

Dermocystidjum salmonis is a gill pathogen of salmonid fishes in the U.S. Pacific Northwest where it has been associated with mortality of adult and juvenile chinook salmon Oncorhynchus tshawytscha. The previously unknown mode of D. salmonis transmission was determined and demonstrated in the laboratory. Uniflagellated zoospores developed within spores obtained from gill cysts and produced infections in pink salmon 0. gorbuscha fry. These infections were lethal, and histological examination of infected gill tissue revealed large numbers of D. salmonis cysts in gill epithelia. Electron microscopic examination of immature spores from experimental infections showed that they were identical to immature spores in naturally infected juvenile chinook salmon.

Parasitism by Dermocystidium ranae in a population of Rana esculenta complex in Central Italy and description of Amphibiocystidium n. gen.

“…Dermocystidium infections have been previously reported in other European anurans: in Alytes obstetricans (Pérez 1913) (Pérez 1913, Poisson 1937). Yet other dermocystidians have been described from fish species, some of which are pathogenic (Cervinka et al 1974, Olson et al 1991, Landsberg & Paperna 1992, Wildgoose 1995.The parasite reported in the present paper is identical grossly, histopathologically and developmentally to Dermocystidium ranae, reported from Rana temporaria by Guyénot & Naville (1922). Bro= & Přívora (1951) also found D. ranae in R. temporaria, but reported spores with single-inclusion bodies, rather than the multiple granules reported from spores in the current paper.…”

“…Dermocystidium infections have been previously reported in other European anurans: in Alytes obstetricans (Pérez 1913) (Pérez 1913, Poisson 1937). Yet other dermocystidians have been described from fish species, some of which are pathogenic (Cervinka et al 1974, Olson et al 1991, Landsberg & Paperna 1992, Wildgoose 1995.…”

Infection of juvenile salmon Salmo salar with a Dermocystidium-like organism in Sweden

“…Electron microscopy also revealed spores with a less prominent vacuole that seemed to be motile. It has been suggested that the signet ring cell represent a vegetative stage that may sporulate to produce infective zoospores (Wotten & McVicar 1980), and it was experimentally demonstrated that uniflagellated zoospores developed from spores within gill cysts from Dermocystidium salmonis (Olson et al 1991). Despite some similarities in spore size and morphology, the striking difference in the choice of microhabitat between the present parasite of salmon and those described earlier from salmonids suggests that this is a previously unknown species.…”

“…The parasite observed in salmon in our study also had similarities to D. salmonis in the choice of host species and predilection site. However, unlike D, salmonis it was never found enclosed within cysts (Davis 1947), and the ultrastructural characteristics were also different (Olson et al 1991). In addition to signet ring cells or hypnospores, multinucleated dividing cells that probably reflected different developmental stages were observed.…”

Systemic granuloma in goldfish caused by a Dermocystidium-like aetiological agent

“…; Perkins 1974). Ultrastructural affinities of the integumental D. salmonis as reported recently by Olson et al (1991) are convincingly different from the causative agent, also named Dermocystidium, of the salmonid systemic granulomatosis as described by Van de Moer et al (1986) and Hedrick et al (1989).…”