DERMOCYSTIDIUM BRANCHIALE LEGER, 1914 (HAPLOSPOREA) FOUND ON THE GILLS OF A COMMON TROUT (SALMO TRUTTA) FROM THE RIVER SVRATKA (CATCHMENT-AREA OF THE DANUBE)

L u c k Y Z., L. G roc h: Dermocystidiumbranchia1e Uger, 1914 (Hap1osporea) Found on the Gills of a Common Trout (Sa1mo trutta) from the River Svratka (Catchment-Area of the Danube). Acta vet. Brno, 57, 1988: 53-60. ' The finding of hap10sporidia of Dermocystidium branchia1e on the gills of a' cOlllDOn trout (Salmo trutta) from the river Svratka near Doubravnilt (catchment-area of the Danube) is reported; It is a second finding of this parasite in Czechoslovakia. Spherical cysts produced by the hap10sporidia on the gill filaments were 0.15 to 0.44 DID in diameter and contained spherical spores of 6 to 10 I'm in diameter. Histological examination revealed moderate regressive changes in the respiratory epithelium of the gills. Dermocystidium branchia1e, Hap10sporea, Salmo trutta, gills, spores. The incidence of parasites in cOlllDOn trout, (~ ~) in Bohemian and Moravian rivers has received rather considerable 'attention in the past few decades as evidenced by their list in the compendium by Erg ens and L 0 m (1970). According to these writers the species Dermocystidium branchia1e has been found so far in Swiss and Irish rivers and its incidence in Czechoslovakia is regarded by them as .very probable. Their presumption was confirmed by us within an investigation into the health status of, COlllDOD trout (~ ~) in the river Svratka by the finding of cysts containing mature spores of hap10sporidia of Dermocystidium branchia1e on the gills of one cOlllDOn trout. The incidence of D. branchia1e in, European rivers seems to be rather rare. According to L ~ g e r (1914) as cited by J i r 0 v e c (1939) this species was found on the gills of Trutta fario in the Dauphinean Alps and was described as asp. n. Dun ker 1 y (1914) as cited by J i r 0 v e c (1939) found it in trout (~ trutta) in Westport (Ireland) and identified it as the species Dermocystidium pusu1a that Per e z (1907) had found in the skin of the newt (Triturus narnoratus) in France and called Dermocystis ~. ' The inforination on Dermocystidium branchia1e (description and the place of its finding) in parasitological and ichtyopatho10gica1 compendia' (D y k

The finding of hap10sporidia of Dermocystidium branchia1e on the gills of a' cOlllDOn trout (Salmo trutta) from the river Svratka near Doubravnilt (catchment-area of the Danube) is reported; It is a second finding of this parasite in Czechoslovakia.
Spherical cysts produced by the hap10sporidia on the gill filaments were 0.15 to 0.44 DID in diameter and contained spherical spores of 6 to 10 I'm in diameter.Histological examination revealed moderate regressive changes in the respiratory epithelium of the gills.Dermocystidium branchia1e, Hap10sporea, Salmo trutta, gills, spores.
The incidence of parasites in cOlllDOn trout, (~ ~) in Bohemian and Moravian rivers has received rather considerable 'attention in the past few decades as evidenced by their list in the compendium by Erg ens and L 0 m (1970).According to these writers the species Dermocystidium branchia1e has been found so far in Swiss and Irish rivers and its incidence in Czechoslovakia is regarded by them as .veryprobable.Their presumption was confirmed by us within an investigation into the health status of, COlllDOD trout (~ ~) in the river Svratka by the finding of cysts containing mature spores of hap10sporidia of Dermocystidium branchia1e on the gills of one cOlllDOn trout.
The incidence of D. branchia1e in, European rivers seems to be rather rare.According to L ~ g e r (1914) as cited by J i r 0 v e c (1939) this species was found on the gills of Trutta fario in the Dauphinean Alps and was described as asp.n.
Dun k e r 1 y (1914) as cited by J i r 0 v e c (1939) found it in trout (~ trutta) in Westport (Ireland) and identified it as the species Dermocystidium pusu1a that P e r e z (1907)  A l l e n et al. ( 1968) described a similar disease not only in adult salmon of the aforementioned species but also in fingerlings and concludeod that an .outbreak of the disease is favoured by temperature lower than 15 C.
In Europe, Woo t ten and Mc Vic a r (1970) described a massive infection in Atlantic salmon in Scotland where particularly young salmon were affected.They found numerous siDallcysts, 1 DIll in diameter, on the gills of adult salmon and described the causative agent as a Dermocystidium sp., without further identification.The wall of the cyst described in their study consisted of fine fibrous tissue and the adjacent.gill epithelium was hyperplastic.In some Atlantic salmon they found para~ites also in other organs (adipose network of the body cavity, liver, heart, .spleen,pancreasand pyloric appendices) and only rearely in the gills and regarded them as members of another species.According to Pro s t (1980) the hosts of D. branchiale are tlle sea trout ( §A!mQ ~) and the cODlllOn trout and the pathological role of the parasite is small.

Mat e r i a 1 s and Me tho d s
Four cOllllllOn trout, 195 to 226 DIll in length and 85 to 141 g in body mass, from the river SVratka (near Iioubravnik) were subjected to parasitological examination on the 3rd of June 1987.Six cODlDOn trout, 198 to 251 DIll in length' and 96 to 138 g in body mass, from the same river were obtained for examination on the 11th of August 1987.Another 6 cODlllOn trout, 175 to 210 DIll in length and 68 to 135 g in body mass, from a stream called Nedvedicka (near Vezrui) were examined on tbe 3rd of August 1987.The NedvediCka is tributary to the Svratka and the two localities from which the trout were obtained are.about 10 km apart.Cysts on the gills (40 specimens) were diagnosed only in one cODlllOn trout from the first locality on the 3rdof June 1987.
The fresh material was fixed with 4 % formol.For species identification, native slide preparations and preparations stained with Giemsa stain and with haematoxylin and eosin were prepared.Histological processing .wascarried out with routine Jllethods' using paraffin blocks stained with 'haematoxylin and eosin and with van Giesonstain.Mature spores were almost spherical in shape and generally 8 ll.lll (6 to 10 flm) in diameter.Examination of the native and 4 % formol-stained preparations showed that the spores contained large, spherical, highly refractive homogenous bodies that were generally located excentrically and some of them could be seen even at the rim of the spore.Their size (4 to 6 fl m in diameter) was proportional to that of the spore.Some spores showed the presence of a spherical or elongated, frequently slightly bent formation of var.ying size.

Description of the
In Giemsa-stained preparations, heavily-staining irregular formations suggestive of the nucleus could occasionally be seen in addition to the refractive body.
In histological sections stained with haematoxylin according to Mayer the staining of the nuclei was very intense.The elongated nuclei were 0.002 to 0.003 times 0.002 flm in size.
The spores were located in small cysts.The cysts exhibiting a marked wall and spherical in shape were found   on the gills both at the base of gill filaments and in the medium and peripheral parts.They were often located between respiratory plate-like projections in the stratified gill epithelium or in the respiratory epithelium.The cysts showed considerable variation in size (15 cysts measured in our study ranged fl'om 0.150 to 0.440 mm in diameter).
Histological examination of the gill samples revealed spherical cystic formations of varying size,generally located between gill filaments.•They were enclosed with a delicate capsule of filamentous collagen and• showed a slightly basophilic granulated content that proved to be a dense accumulation of spherical spores when examined under higher magnification.Inside the spore a large light vacuole was located slightly excentrically.Its content did not stain with alcian blue and therefore contained no acid mucopolysaccharides.Positive reaction for mucopolysaccharides was shown only by the cell membrane.Located at the periphery of the spore was the basophilic ovoid or slightly curved nucleus.
The respiratory epithelium adjacent to the cysts showed regressive changes of various degree: it was atrophic at the sites of direct contact with the cysts and showed dystrophic injury manifested by vacuolization of the cytoplasm, impaired outline of the cell and occasionally also by necrobiotic changes of the nuclei in more distant areas.A frequent accompanying finding was passive hyperaemia of the gill tissue.No reactive inflammatory processes at the gill epithelium adjacent to the cysts were observed.This finding suggests that the cysts in the gill tissue increase slowly and do not produce a morphologically distinct defensive response of the host.Dermocystidium branchiale Leger, 1914 Fig. 1.Spores of Dermocystidium branchiale showing a large refractive vacuole and the elongated nucleus.
had found in the skin of the newt (Triturus narnoratus) in France and called Dermocystis ~.Ii s k 0 v Ii(1985)who found it on the gills of cODlllOn trout in the brook Borovnice in South• Bohemia .' in 1980.Besides the description of the specimens, her report is concerned with the taxonomy of the genus