Site preference of myxozoans in the kidneys of Hungarian fishes

Abstract

Myxozoans are common parasites of fish kidneys, with most having specific sites of development. Five specific sites of development include (1) the lumen of renal tubules, (2) the renal corpuscles followed by location in renal tubules, (3) intracellular location within the tubular epithelium followed by a stage in the lumen of the ducts, (4) haematopoietic tissue with dispersed trophozoites, and (5) haematopoietic tissue with large, localized plasmodia. A coelozoic development preceded by presporogonic multiplication characterises most Sphaerospora spp. Early plasmodial stages of Myxidium and Chloromyxum spp. are frequently found in the renal glomerules, while spores develop in the urinary channels in plasmodia released from the renal corpuscles. In Hoferellus and Myxobilatus spp., spores are formed in small plasmodia inside the lumen of the urinary ducts after several internal cleavages in the epithelium of renal tubules. The presence of dispersed trophozoites among haematopoietic tissue cells of the renal interstitium characterises the development of Sphaerospora tincae and Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease (PKD). Spores of S. tincae are formed at the place of plasmodial development, while spore formation of PKD is in the renal tubules. A large mass of spores, often surrounded by a connective tissue capsule, can appear in the renal interstitium during infections by several Myxobolus spp.; furthermore, a large number of these spores formed in plasmodia in distant tissues can also accumulate in melano-macrophage centres.KEY WORDS: Myxozoa · Plasmodia · Site preference · Fish · Kidney Resale or republication not permitted without written consent of the publisherDis Aquat Org 78: [45][46][47][48][49][50][51][52][53] 2007 tench. This isolated intercellular location among the haemopoetic cells was confirmed with electron microscopy by Lom et al. (1985a). A specific combination of intercellular and coelozoic developments characterise Tetracapsuloides bryosalmonae (Canning, Curry, Feist, Longshaw & Okamura, 1999), the causative agent of proliferative kidney disease. Extrasporogonic stages of this myxozoan develop intercellularly among the cells of the renal interstitium; the spores, however, are formed in the renal tubules (Kent et al. 2000, Feist et al. 2001. Little is known about how myxozoans form large plasmodia in the kidney. Although it has been known for some time (Dyková et al. 1987) that plasmodia of Myxidium rhodei Léger, 1905 can form large plasmodia inside the renal corpuscles of cyprinids, little is known about the validity of the great number of Myxobolus spp. listed from the kidney by Shulman (1966). Dispersed spores and large groups of Myxobolus spores are commonly found in the renal parenchyma, but without observation of the developing stages it is difficult to determine whether the spores developed at the site or were carried and accumulated there by the host macrophages. Molnár & Kovács-Gayer (1985) observed that, following a heavy infect...

Light and electron microscopic studies on turbot Psetta maxima infected with Enteromyxum scophthalmi: histopathology of turbot enteromyxosis

“…Scale bar = 2 µm sponse vary greatly depending on the host species (Padrós et al 2001, Álvarez-Pellitero et al 2008, Fleurance et al 2008. Similarly, the current results on turbot enteromyxosis demonstrated that the inflammatory response in the digestive tract was not always correlated with the number of parasites populating the epithelium, as has been previously reported (Bermúdez et al 2006b, 2007). An interesting finding was the initial increase in the amount of both rodlet and goblet cells, followed by a decrease in their number in fish suffering severe infections (Vigliano et al 2004).…”

“…Although the vast majority of Myxosporea develops in any part of the fish body (Lom & Dyková 1995, Molnár 2007, few of them are described from enteric locations (Lom & Dyková 1995, Padrós et al 2001, Álvarez-Pellitero et al 2008. Ceratomyxa shasta, causing an important disease in salmonids, invades the intestinal epithelium, though the infection may become disseminated to several organs (Bartholomew et al 1989).…”

Specificity of Infection Sites in Vertebrate Hosts

“…In most cases, the occurrence and development of these parasites can be attributed to a specific part or tissue of this organ. Five major sites of infection were distinguished (Molnár 2007). Most coelozoic myxozoans developing spores in the kidney have a presporogonic stage in the blood or in the renal glomeruli before sporogony in the kidney tubules or in the ureter.…”

Prevalence and Mean Intensity of Myxobolus spp. Parasitizing Oreochromis niloticus in Cameroon

“…plays an essential role in antigen trapping (Press, 1998) while the kidney, receiving the vast majority of postbranchial blood is expected to receive all pathogens present in the blood. Accounts on fish host and organ specificity of myxosporidia species are often confusing (Molnár, 2002(Molnár, , 2007, including those concerning species of the genus Myxobolus. Whereas sporogenesis of some coelozoic species was originally described in the kidney, other authors observed that spores of some histozoic species, secondarily occur in haematopoietic organs (Molnár, 2007).…”

“…Accounts on fish host and organ specificity of myxosporidia species are often confusing (Molnár, 2002(Molnár, , 2007, including those concerning species of the genus Myxobolus. Whereas sporogenesis of some coelozoic species was originally described in the kidney, other authors observed that spores of some histozoic species, secondarily occur in haematopoietic organs (Molnár, 2007). According to Dyková (1984), myxospores are generally transported by macrophages homing on macrophage centers of haematopoietic organs, where they are destroyed.…”