Proliferative kidney disease in Switzerland: current state of knowledge

This study presents an overview of the distribution of proliferative kidney disease (PKD) in wild and farmed fish in Switzerland based on two sources: (1) the results of routine diagnostic work at the National Fish Disease Laboratory, and (2) the results of a country‐wide survey for PKD. The first case of PKD in Switzerland was diagnosed in 1979 and since 1981, a few cases have been found every year. Affected species were rainbow trout, brown trout and grayling from rivers and fish farms. Most of the diseased fish were found in the lower altitude regions of the country (Swiss midlands). A seasonal distribution of the cases was evident: PKD‐positive fish occurred only from June to November withprominent peaks in August and September. Among infected fish all length classes were present, but the highest numbers of affected fish were found in the length classes <10 cm and 16–20 cm. The evaluation of the samples from a survey of the occurrence of PKD in 2000/2001 revealed a much broader geographical distribution of the infection than expected from routine diagnostic observations. Fish from 56 of 139 rivers analysed by histological examination were positive for parasites. Fish from 131 of these sites were examined macroscopically. Of these, trout from 45 sites showed gross alterations indicative for PKD. Most of the positive fish were found in the Swiss midlands north of the Alps. Fish from six of 65 fish farms investigated were found to be PKD‐positive by histopathological analysis, and in four of these cases fish could be identified as infected on the basis of gross examination.     

Proliferative kidney disease of salmonid fish: a review

Abstract A detailed review of proliferative kidney disease (PKD) in salmonids is presented. The introduction places the disease in a historical context. The various aspects of the disease are described from the existing literature, together with latest findings from current research. Particular emphasis is given to epidemiology, aetiology and pathology.     

Proliferative kidney disease in rainbow trout Salmo gairdneri Richardson

Abstract. Two entirely separate outbreaks of PKD are described in an attempt to properly define the condition and enable it to be differentiated from other diseases of a similar nature. Losses of up to 75% of fingerling rainbow trout were recorded in one outbreak, illustrating the potentially serious nature of the disease. Although the kidneys showed the most obvious pathological changes, other organs were also affected. The host response was granulomatous in type, the foci of each cellular reaction being 5-20 μm eosinophilic cells considered to be parasitic. The cytoplasm of these cells contained numerous electron dense bodies some with a tail, but each with an electron lucent bar always orientated at right angles to the plasmalemma whenever they were near it. The most obvious cytoplasmic inclusion of these 'parasites' were other cells numbering up to five or six, each with its own nucleus and nucleolus, but devoid of any of the small electron dense bodies. The significance of either of these inclusions is unknown.
A limited differential diagnosis is given, and the argument presented that the condition PKD is the result of infection by a parasite, possibly an amoeba, in combination with poor quality water.     

Proliferative kidney disease (PKD) of salmonids

Proliferative Kidney Disease (PKD) of salmonids, pathology, occurrence and the causative agent are described according to recent literature. For diagnosis histology and/or impression smears of infected kidneys are recommended. Original coloured photos are added to serve this purpose.     

Proliferative kidney disease and renal myxosporidiosis in juvenile salmonids from rivers in England and Wales

The results from a survey for proliferative kidney disease (PKD) and renal myxosporidiosis in wild salmonids from rivers in England and Wales are presented. One hundred and eighty-five salmon, Salmo salar , 235 brown trout, Salmo trutta , 16 charr, Salvelinus alpinus, and five grayling, Thymallus thymallus, were obtained from 23 locations on 16 rivers between July and October 1997. They were examined for the presence of clinical PKD and for histological evidence of infections with Tetracapsula bryosalmonae and other renal myxozoans. Prevalence of infection with T. bryosalmonae detected histologically in brown trout varied from 11 to 43% in enzootic rivers and was only found in salmon in two rivers at low prevalence. Nephromegaly was positively associated with PKD in brown trout but in salmon mild nephromegaly was only associated with infection with an unidentified Chloromyxum sp.     

北美大嘴鲈鱼病毒病的研究现状

大嘴鲈鱼(MicropterusSalmoides)广泛分布于北美各主要水域,大嘴鲈鱼病毒(LargeMouth BassVirus,以下简称LMBV)是一种已知的、唯一能引起大嘴鲈鱼致死性疾病的一种病毒。此病毒隶属于虹彩病毒科,由于受该病毒感染的鱼体没有明显的、易于观察的临床症状,所以很难做出早期诊断。有关LMBV和由该病毒引起病毒病的报导很多,本文仅收集与综合了国外一些主要的相关文章,以促进对该病的进一步研究和探讨。     

Proliferative kidney disease (PKD) in rainbow trout Salmo gairdneri: Further observations on the effects of water temperature

The seasonality of proliferative kidney disease (PKD) and the effects of water temperature on the development of the disease in naturally-infected fingerling rainbow trout, Salmo gairdneri, were investigated. Fingerling rainbow trout became infected from May to October, but those infected in October did not develop clinical disease. In naturally-infected fish subsequently held under laboratory conditions, clinical PKD occurred at 12–18°C, but not at 9°C. The disease progressed more rapidly and was more severe as temperatures increased. On re-exposure to infection, rainbow trout previously held at 9°C developed clinical PKD, whereas in those previously held at 12°C it did not develop. Possible implications of these findings for the control of PKD are discussed.     

Proliferative kidney disease: cellular aspects of the rainbow trout, Oncorhynchus mykiss (Walbaum), response to parasitic infection

Proliferative kidney disease (PKD) is an immunopathological condition of salmonid fish, caused by the hyperplastic response of their principal lymphoid tissues to infection with the spores of Tetracapsula bryosalmonae , a myxozoan parasite formerly designated proliferative kidney organism – unknown (PKX). In order to investigate the nature of cells involved in this host response and possible alterations of their functions during parasitic infection the course of PKD was studied by flow cytometry (FCM) techniques, using blood, pronephros and spleen leucocyte populations from rainbow trout infected by intraperitoneal (i.p.) injection with parasitic cells from infected donor fish. The parameters of the cellullar response studied were: cytogram of cell population, lymphoproliferation, phagocytosis, oxidative burst, and non-specific cytotoxicity. The modifications of cell population distribution and function in the PKD-infected fish mainly affected the pronephros cell populations and were coincident with the clinical phase of disease. During this phase, the lymphocytes constituted the major leucocyte cell population and underwent proliferation and were thus responsible for the renal tissue hyperplasia. Meanwhile, phagocytosis and oxidative burst were depressed. These data are in agreement with the patho-epidemiological background of PKD where the enhancement of the fish sensitivity to bacterial infections reflects the impairment of certain cellular defence mechanisms of innate immunity.     

北美鲟鱼种类及其生物学

鲟鱼是目前地球上最古老和最原始的软骨鱼类 ,它们大多个体较大 ,大约在 2亿 5千万年前演变而成。鲟鱼目前尚保留了不少原始鱼的特征 ,如尾鳍歪形 ,体内除头骨外都是软骨 ,体外表皮无鳞但有五行骨板 ,多数个体大且寿命较长。在分类上 ,鲟鱼属于辐鳍亚纲 ,硬鳞总目 ,鲟形目。全球现存的鲟鱼有两个科 ,即鲟科和匙吻鲟科 (或称白鲟科 ) ,共 2 8种。在北美现存有鲟鱼共 8种 ,包括鲟科鱼 7种和匙吻鲟科鱼 1种 ,具体见表 1。北美鲟鱼与世界各地的其它鲟鱼一样 ,有表 1　北美现存的鲟鱼种类中文名英文名学　　名匙吻鲟Ａｍｅｒｉｃａｎｐａｄｄｌｅ…     

中华绒螯蟹在北美洲

介绍并分析了中华绒螯蟹侵移北美洲的过程以及目前的分布情况。     

Proliferative kidney disease in brown trout, Salmo trutta L., and Atlantic salmon, Salmo salar L., parr: histopathological and epidemiological observations

Abstract Proliferative kidney disease (PKD) has been described in cultivated rainbow trout but major outbreaks have not been recognized in other fish species. This paper describes light and electron microscope studies and presents epidemiological data of a disease condition in first summer Salmo salar parr and S. trutta , which is associated with an organism apparently identical to the aetiological agent of PKD. The pathology was found to be similar to that described for PKD in rainbow trout. The epidemiology in the brown trout suggests that exposure after May does not result in infection. The data from the outbreaks in two salmon hatcheries appear complex and suggest different susceptibilities to PKD among salmon originating from different sources.     

Influence of water quality on the outbreak of proliferative kidney disease – field studies and exposure experiments

This paper presents data from field studies and exposure experiments and the possible association of limno- and physicochemical parameters with outbreaks of proliferative kidney disease (PKD) in rainbow and brown trout. The investigations were carried out at Singold Brook in southern Germany. Exposure experiments and sampling of wild fish were performed in Singold at least twice a year in 1992, 1994, 1996 and 2000. Both wild fish collected from the specific sites and experimentally exposed rainbow trout were investigated histologically for the occurrence of PKD. At the time of sampling, various water parameters at the respective river sites were measured. The results indicate strongly the existence of a correlation between organic pollution of water, the presence of Bryozoa and the outbreak of PKD.     

Bacterial kidney disease in salmonids

Bacterial kidney disease (BKD) is the most important bacterial infection in salmonid fish. Clinics, pathomorphology, distribution and possibility of therapy of BKD are discussed regarding results of literature as well as own experiences.     

Life history trait diversity of native freshwater fishes in North America

Mims MC, Olden JD, Shattuck ZR, Poff NL. Life history trait diversity of native freshwater fishes in North America.
Ecology of Freshwater Fish 2010: 19: 390–400. © 2010 John Wiley & Sons A/S Abstract – Freshwater fish diversity is shaped by phylogenetic constraints acting on related taxa and biogeographic constraints operating on regional species pools. In the present study, we use a trait‐based approach to examine taxonomic and biogeographic patterns of life history diversity of freshwater fishes in North America (exclusive of Mexico). Multivariate analysis revealed strong support for a tri‐lateral continuum model with three end‐point strategies defining the equilibrium (low fecundity, high juvenile survivorship), opportunistic (early maturation, low juvenile survivorship), and periodic (late maturation, high fecundity, low juvenile survivorship) life histories. Trait composition and diversity varied greatly between and within major families. Finally, we used occurrence data for large watersheds (n = 350) throughout the United States and Canada to examine geographic patterns of life history variation. Distinct patterns of life history strategies were discernible and deemed congruent with biogeographic processes and selection pressures acting on life history strategies of freshwater fishes throughout North America.