Pathology of experimental amoebic gill disease in Atlantic salmon, <i>Salmo salar</i> L., and the effect of pre‐maintenance of fish in sea water on the infection

Zilberg, Dina; Munday, B. L.

doi:10.1046/j.1365-2761.2000.00252.x

Cited by 56 publications

(73 citation statements)

References 8 publications

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“…The parasome has been identified as a symbiotic organism, Perkinsiella amoebae (Dyková et al 2000), and is found in a variety of amoeba species. Additionally Neoparamoeba has been shown to be Alcian blue positive (Zilberg & Munday 2000). Immunofluoresce staining procedures have been developed for identification of this parasite in gill smears and sections (Howard & Carson 1993).…”

Section: Taxamentioning

confidence: 99%

Guide to the identification of fish protozoan and metazoan parasites in stained tissue sections

Bruno¹,

Nowak²,

Elliott³

2006

Dis. Aquat. Org.

103

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The identification of protozoan and metazoan parasites is traditionally carried out using a series of classical keys based upon the morphology of the whole organism. However, in stained tissue sections prepared for light microscopy, taxonomic features will be missing, thus making parasite identification difficult. This work highlights the characteristic features of representative parasites in tissue sections to aid identification. The parasite examples discussed are derived from species affecting finfish, and predominantly include parasites associated with disease or those commonly observed as incidental findings in disease diagnostic cases. Emphasis is on protozoan and small metazoan parasites (such as Myxosporidia) because these are the organisms most likely to be missed or mis-diagnosed during gross examination. Figures are presented in colour to assist biologists and veterinarians who are required to assess host/parasite interactions by light microscopy.

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Section: Taxamentioning

confidence: 99%

Guide to the identification of fish protozoan and metazoan parasites in stained tissue sections

Bruno¹,

Nowak²,

Elliott³

2006

Dis. Aquat. Org.

103

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“…In addition to N. pemaquidensis, the closely related N. aestuarina should be taken into consideration as well as a supposed third Neoparamoeba species (Fiala and Dyková 2003). The data accumulated on pathogenicity of the AGD agent in Atlantic salmon and on host-parasite relationships (Findlay et al 1998, Clark and Nowak 1999, Zilberg et al 1999, Douglas-Helders et al 2000, 2001b, 2002, Zilberg and Munday 2000, Adams and Nowak 2001, Elliot et al 2001) strongly influence the search for potential pathogens among other amoebae.…”

Section: Gill-infecting Speciesmentioning

confidence: 99%

Advances in the knowledge of amphizoic amoebae infecting fish

Dyková¹,

Lom²

2004

FOLIA PARASIT

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Abstract. Free-living amoebae infecting freshwater and marine fish include those described thus far as agents of fish diseases, associated with other disease conditions and isolated from organs of asymptomatic fish. This survey is based on information from the literature as well as on our own data on strains isolated from freshwater and marine fish. Evidence is provided for diverse fish-infecting amphizoic amoebae. Recent progress in the understanding of the biology of Neoparamoeba spp., agents responsible for significant direct losses in Atlantic salmon and turbot industry, is presented. Specific requirements of diagnostic procedures detecting amoebic infections in fish and taxonomic criteria available for generic and species determination of amphizoic amoebae are analysed. The limits of morphological and non-morphological approaches in species determination are exemplified by Neoparamoeba, Vannella and Platyamoeba spp., which are the most common amoebae isolated from fish gills, Acanthamoeba and Naegleria spp. isolated from various organs of freshwater fish, and by other unique fish isolates of the genera Nuclearia, Thecamoeba and Filamoeba. Advances in molecular characterisation of SSU rRNA genes and phylogenetic analyses based on their sequences are summarised. Attention is particularly given to specific diagnostic tools for fish-infecting amphizoic amoebae and ways for their further development.

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“…Gill pathology of AGD-affected fish involves epithelial hyperplasia, as well as mucous cell hyperplasia and an extensive mucus secretion (Munday et al 1990, Nowak & Munday 1994, Zilberg & Munday 2000, Roberts & Powell 2003a. It has been previously suggested that excessive branchial mucus impairs CO 2 excretion, leading to respiratory acidosis and subsequent death in AGD affected fish (Powell et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Oral l-cysteine ethyl ester (LCEE) reduces amoebic gill disease (AGD) in Atlantic salmon Salmo salar

Roberts

Powell²

2005

Dis. Aquat. Org.

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There is a need for the development of alternative therapeutic treatments for amoebic gill disease (AGD) in Atlantic salmon Salmo salar L. to maintain the sustainability of the Tasmanian Atlantic salmon aquaculture industry. This study aimed to assess the effects of the mucolytic drug L-cysteine ethyl ester (LCEE) on marine Atlantic salmon mucus and whether or not it may have a therapeutic advantage for the alleviation of AGD when administered orally. We also aimed to document any physiological consequences of LCEE. Results showed that LCEE significantly decreased the viscosity of marine Atlantic salmon mucus both in vitro, where LCEE concentration showed a negative relationship to mucus viscosity (R 2 = 0.95 at 11.5 s -1 ), and in vivo. Oral administration of LCEE at 52.7 mg LCEE kg -1 fish d -1 over 2 wk significantly delayed the progression of AGDassociated pathology during an aggressive, cohabitation induced, laboratory infection. Medicated fish had approximately 50% less gill filaments affected by AGD than control fed fish at 3 d postinfection when assessed using histology. Palatability of medicated feed was shown to be approximately 65% of control feed. No osmoregulatory disturbance was seen in medicated fish, although blood and whole body flux data indicated a slight acidosis coinciding with an increased plasma total ammonia concentration. However, both variables were within a tolerable physiological range and returned to control levels 3 d post-cessation of medicated feed. LCEE holds potential as an in-feed additive when administered over 2 wk prior to infection to delay the progression of AGD associated pathology. From the parameters measured, LCEE seems to have minimal physiological consequences after 2 wk of administration. KEY WORDS: Fish gill disease · Salmonid · In-feed treatment · Oral therapeutant · Mucolytic drug · Mucus viscosity · Physiological effects Resale or republication not permitted without written consent of the publisherDis Aquat Org 66: [21][22][23][24][25][26][27][28] 2005 Roberts & Powell 2003a). It has been previously suggested that excessive branchial mucus impairs CO 2 excretion, leading to respiratory acidosis and subsequent death in AGD affected fish (Powell et al. 2000). The break-up and removal of mucus from the gills seems to be an important function of freshwater bathing as a treatment . Indeed, freshwater bathing has been shown to significantly decrease mucus viscosity of marine Atlantic salmon (Roberts 2004). Thinner and more removable mucus is thought to aid the significant lesion fragmentation and shedding of AGD lesion-associated hyperplastic gill tissue, as well as sloughing of gill-associated amoebae in soft, freshwater-bathed fish (Roberts & Powell 2003b).Therapeutic mucolytic drugs have been extensively used for the alleviation of respiratory diseases associated with excessive production and accumulation of mucus in humans and domestic animals. N-acetylcysteine (NAC) is a widely used mucolytic agent that by virtue of its free sulfhydryl group reacts w...

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Pathology of experimental amoebic gill disease in Atlantic salmon, Salmo salar L., and the effect of pre‐maintenance of fish in sea water on the infection

Cited by 56 publications

References 8 publications

Guide to the identification of fish protozoan and metazoan parasites in stained tissue sections

Guide to the identification of fish protozoan and metazoan parasites in stained tissue sections

Advances in the knowledge of amphizoic amoebae infecting fish

Oral l-cysteine ethyl ester (LCEE) reduces amoebic gill disease (AGD) in Atlantic salmon Salmo salar

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