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Brocca G, Truant A, Peckova H, Lisnerová M, Perolo A, Fioravanti M, Fiala I, Gabai G, Quaglio F, Gustinelli A. Identification of new amoebae strains in rainbow trout (Oncorhynchus mykiss, Walbaum) farms affected by nodular gill disease (NGD) in Northeastern Italy. JOURNAL OF FISH DISEASES 2024; 47:e13933. [PMID: 38400598 DOI: 10.1111/jfd.13933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/26/2024] [Accepted: 01/30/2024] [Indexed: 02/25/2024]
Abstract
Nodular gill disease (NGD) is an emerging condition associated with amoeba trophozoites in freshwater salmonid farms. However, unambiguous identification of the pathogens still must be achieved. This study aimed to identify the amoeba species involved in periodic NGD outbreaks in two rainbow trout (Oncorhynchus mykiss) farms in Northeastern Italy. During four episodes (February-April 2023), 88 fish were euthanized, and their gills were evaluated by macroscopic, microscopic and histopathological examination. The macroscopic and microscopic severity of the lesions and the degree of amoebae infestation were scored and statistically evaluated. One gill arch from each animal was put on non-nutrient agar (NNA) Petri dishes for amoeba isolation, cultivation and subsequent identification with SSU rDNA sequencing. Histopathology confirmed moderate to severe lesions consistent with NGD and mild to moderate amoeba infestation. The presence of amoebae was significantly correlated with lesion severity. Light microscopy of cultured amoebae strains and SSU rDNA analysis revealed the presence of a previously characterized amoeba Naegleria sp. strain GERK and several new strains: two strains from Hartmannelidae, three vannelid amoebae from the genus Ripella and cercozoan amoeba Rosculus. Despite the uncertainty in NGD etiopathogenesis and amoebae pathogenic role, identifying known and new amoebae leans towards a possible multi-aetiological origin.
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Affiliation(s)
- Ginevra Brocca
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, Padua, Italy
- Aquatic Diagnostic Services, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
| | - Alessandro Truant
- Department of Animal Medicine, Production and Health, University of Padova, Legnaro, Padua, Italy
| | - Hana Peckova
- Institute of Parasitology, Biology Centre CAS, Ceske Budejovice, Czech Republic
| | - Martina Lisnerová
- Institute of Parasitology, Biology Centre CAS, Ceske Budejovice, Czech Republic
| | - Alberto Perolo
- Servizio Tecnico Commerciale Aquafeed, Gruppo Veronesi, Verona, Veneto Region, Italy
| | - Marialetizia Fioravanti
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, Ozzano dell'Emilia, Bologna, Italy
| | - Ivan Fiala
- Institute of Parasitology, Biology Centre CAS, Ceske Budejovice, Czech Republic
| | - Gianfranco Gabai
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, Padua, Italy
| | - Francesco Quaglio
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, Padua, Italy
| | - Andrea Gustinelli
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, Ozzano dell'Emilia, Bologna, Italy
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Rahmati-Holasoo H, Niyyati M, Fatemi M, Mahdavi Abhari F, Shokrpoor S, Nassiri A, Marandi A. Molecular identification, phylogenetic analysis and histopathological study of pathogenic free-living amoebae isolated from discus fish (Symphysodon aequifasciatus) in Iran: 2020-2022. BMC Vet Res 2024; 20:54. [PMID: 38347572 PMCID: PMC10860241 DOI: 10.1186/s12917-024-03902-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 01/28/2024] [Indexed: 02/15/2024] Open
Abstract
Free-living amoebae (FLA) are capable of inhabiting diverse reservoirs independently, without relying on a host organism, hence their designation as "free-living". The majority of amoebae that infect freshwater or marine fish are amphizoic, or free-living forms that may colonize fish under particular circumstances. Symphysodon aequifasciatus, commonly referred to as the discus, is widely recognized as a popular ornamental fish species. The primary objective of the present study was to determine the presence of pathogenic free-living amoebae (FLA) in samples of discus fish. Fish exhibiting clinical signs, sourced from various fish farms, were transferred to the ornamental fish clinic. The skin, gills, and intestinal mucosa of the fish were collected and subjected to culturing on plates containing a 1% non-nutrient agar medium. The detection of FLA was conducted through morphological, histopathological and molecular methods. The construction of the phylogenetic tree for Acanthamoeba genotypes was achieved using the maximum likelihood approach. The molecular sequence analysis revealed that all cultures that tested positive for FLA were T4 genotype of Acanthamoeba and Acanthamoeba sp. The examination of gill samples using histopathological methods demonstrated the presence of lamellar epithelial hyperplasia, significant fusion of secondary lamellae, and infiltration of inflammatory cells. A multitude of cysts, varying in shape from circular to elliptical, were observed within the gills. The occurrence of interlamellar vesicles and amoeboid organisms could be observed within the epithelial tissue of the gills. In the current study, presence of the Acanthamoeba T4 genotype on the skin and gills of discus fish exhibiting signs of illness in freshwater ornamental fish farms was identified. This observation suggests the potential of a transmission of amoebic infection from ornamental fish to humans, thereby highlighting the need for further investigation into this infection among ornamental fish maintained as pets, as well as individuals who interact with them and their environment.
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Affiliation(s)
- Hooman Rahmati-Holasoo
- Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
| | - Maryam Niyyati
- Department of Medical Parasitology and Mycology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Marziye Fatemi
- Department of Medical Parasitology and Mycology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fatemeh Mahdavi Abhari
- Student Research Committee, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Sara Shokrpoor
- Department of Pathology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
| | - Alireza Nassiri
- Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
| | - Amin Marandi
- Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
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Patchett AL, Rigby ML, Wynne JW. Improved 18S rDNA profiling of parasite communities in salmonid tissues using a host blocking primer. Parasitol Res 2024; 123:124. [PMID: 38319497 PMCID: PMC10847071 DOI: 10.1007/s00436-024-08136-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 01/18/2024] [Indexed: 02/07/2024]
Abstract
Sensitive screening of eukaryotic communities in aquaculture for research and management is limited by the availability of technologies that can detect invading pathogens in an unbiased manner. Amplicon sequencing of 18S ribosomal DNA (rDNA) provides a potential pan-diagnostic test to overcome these biases; however, this technique is limited by a swamping effect of host DNA on low abundance parasite DNA. In this study, we have adapted a host 18S rDNA blocking assay to amplify eukaryotic DNA from salmonid tissue for amplicon sequencing. We demonstrate that effective salmonid 18S rDNA blocking enables sensitive detection of parasite genera in salmonid gill swabs. Furthermore, 18S rDNA amplicon sequencing with host blocking identified enriched pathogen communities in gill swabs from Atlantic salmon suffering from severe clinical gill infections compared to those exhibiting no clinical signs of gill infection. Application of host 18S rDNA blocking in salmonid samples led to improved detection of the amoebic parasite Neoparamoeba perurans, a parasite of significant threat to the Atlantic salmon aquaculture industry. These results reveal host 18S rDNA blocking as an effective strategy to improve the profiling and detection of parasitic communities in aquaculture species. This assay can be readily adapted to any animal species for improved eukaryotic profiling across agricultural and veterinary industries.
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Affiliation(s)
| | - Megan L Rigby
- CSIRO Agriculture and Food, Hobart, Tasmania, 7001, Australia
| | - James W Wynne
- CSIRO Agriculture and Food, Hobart, Tasmania, 7001, Australia
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Cocco A, Toson M, Perolo A, Casarotto C, Franzago E, Brocca G, Verin R, Quaglio F, Dalla Pozza M, Bille L. Nodular gill disease in Northeastern Italy: An investigation on the prevalence of the disease and the risks of introduction in rainbow trout farms. JOURNAL OF FISH DISEASES 2023; 46:1021-1028. [PMID: 37309570 DOI: 10.1111/jfd.13821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 05/25/2023] [Accepted: 05/29/2023] [Indexed: 06/14/2023]
Abstract
Nodular Gill Disease (NGD) is an emerging pathogenic condition that causes gill damage and mainly affects farmed freshwater fish, rainbow trout (Oncorhynchus mykiss) in particular, and this inevitably generates noticeable economic losses for the industry. The present study aimed to assess the prevalence of NGD in the Autonomous Province of Trento, a highly productive area located in Northeastern Italy, traditionally suited to rainbow trout production, and to identify possible risk factors for the introduction of this disease in trout farms. The necessary data were obtained through a questionnaire and the collection of fish samples. According to the data analysis, 42% of the investigated farms tested positive for NGD. The two possible risk factors identified for its introduction in farms are the presence of other diseases in the same farm (OR = 17.5; 95% CI = 2.7; 111.5) and having farms located 5 km upstream (OR = 24.8; 95% CI = 2.9; 211.1). These results highlight (i) a possible impairment of the immune system caused by other diseases as a predisposing factor to the manifestation of the pathology and (ii) the role of water in spreading pathogens.
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Affiliation(s)
- Alessia Cocco
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro (PD), Italy
| | - Marica Toson
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro (PD), Italy
| | | | - Claudia Casarotto
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro (PD), Italy
| | - Eleonora Franzago
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro (PD), Italy
| | - Ginevra Brocca
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro (PD), Italy
- Aquatic Diagnostic Services, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
| | - Ranieri Verin
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro (PD), Italy
| | - Francesco Quaglio
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro (PD), Italy
| | - Manuela Dalla Pozza
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro (PD), Italy
| | - Laura Bille
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro (PD), Italy
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Vannetti SM, Wynne JW, English C, Huynh C, Knüsel R, de Sales-Ribeiro C, Widmer M, Delalay G, Schmidt-Posthaus H. Amoeba species colonizing the gills of rainbow trout (Oncorhynchus mykiss) in Swiss aquaculture. JOURNAL OF FISH DISEASES 2023; 46:987-999. [PMID: 37294659 DOI: 10.1111/jfd.13819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 05/14/2023] [Accepted: 05/17/2023] [Indexed: 06/11/2023]
Abstract
Nodular gill disease (NGD) is an infectious condition characterized by proliferative gill lesions leading to respiratory problems, oxygen deficiency and mortality in fish. Globally, NGD primarily impacts freshwater salmonids in intensive aquaculture systems. In recent years, numerous outbreaks of severe gill disease have affected more than half of the larger rainbow trout (Oncorhynchus mykiss) farms in Switzerland, mainly during spring and early summer. Mortality has reached up to 50% in cases where no treatment was administered. Freshwater amoeba are the presumed aetiologic agent of NGD. The gross gill score (GS) categorising severity of gill pathology is a valuable first-line diagnostic tool aiding fish farmers in identifying and quantifying amoebic gill disease (AGD) in farmed marine salmonids. In this study, the GS was adapted to the NGD outbreak in farmed trout in Switzerland. In addition to scoring disease severity, gill swabs from NGD-affected rainbow trout were sampled and amoeba were cultured from these swabs. Morphologic and molecular methods identified six amoeba strains: Cochliopodium sp., Naegleria sp., Vannella sp., Ripella sp., Saccamoeba sp. and Mycamoeba sp. However, the importance of the different amoeba species for the onset and progression of NGD still has to be evaluated. This paper presents the first description of NGD with associated amoeba infection in farmed rainbow trout in Switzerland.
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Affiliation(s)
- Stefania M Vannetti
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Institute for Fish and Wildlife Health, University of Bern, Bern, Switzerland
- Fishdoc GmbH, Rain, Switzerland
| | - James W Wynne
- CSIRO Agriculture and Food, Tasmania, Hobart, Australia
| | - Chloe English
- School of Biological Sciences, The University of Queensland, Queensland, Brisbane, Australia
| | | | | | - Carolina de Sales-Ribeiro
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Institute for Fish and Wildlife Health, University of Bern, Bern, Switzerland
| | - Maro Widmer
- Interfaculty Bioinformatics Unit and SIB Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland
| | - Gary Delalay
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Institute for Fish and Wildlife Health, University of Bern, Bern, Switzerland
| | - Heike Schmidt-Posthaus
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Institute for Fish and Wildlife Health, University of Bern, Bern, Switzerland
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Kudryavtsev A, Parshukov A, Kondakova E, Volkova E. Vannella mustalahtiana sp. nov. (Amoebozoa, Vannellida) and rainbow trout nodular gill disease (NGD) in Russia. DISEASES OF AQUATIC ORGANISMS 2022; 148:29-41. [PMID: 35142296 DOI: 10.3354/dao03641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
An outbreak of nodular gill disease (NGD) in farmed rainbow trout Oncorhynchus mykiss (Walbaum, 1792) was recorded in Ladoga Lake (Karelia, north-western Russia) in Spring 2020. The disease was characterised by typical clinical signs including asphyxiation, distended opercula, loss of activity and swimming upside down under the water surface. Maximum monthly mortality was 15.2%. The histological examination of the gills showed deformation and clubbing of lamellae, epithelial hypertrophy and hyperplasia, lamellar fusion and fusion of filaments. Granulomas were located within the epithelial layer and/or rose above its surface. Light microscopic in vivo observations of the mucus smears from the affected gills revealed numerous amoeboid protists demonstrating a flattened body when adhering to the substratum, and blunt, radiating pseudopodia when afloat. Based on these morphological characters, these amoebae could be assigned to the Discosea (Amoebozoa), and analyses of their small subunit rRNA gene sequences showed that they belonged to the genus Vannella Bovee, 1965. The results reported herein support the designation of a new species, V. mustalahtiana sp. nov. Despite having been isolated from the gills of a freshwater fish, the species belongs to a clade of Vannella comprising mostly species isolated from marine and brackish water habitats. These findings may be essential for the aetiology and treatment of the disease.
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Affiliation(s)
- Alexander Kudryavtsev
- Laboratory of Cellular and Molecular Protistology, Zoological Institute, Russian Academy of Sciences, 199034 Saint Petersburg, Russia
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Padrós F, Constenla M. Diseases Caused by Amoebae in Fish: An Overview. Animals (Basel) 2021; 11:991. [PMID: 33916144 PMCID: PMC8065943 DOI: 10.3390/ani11040991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/28/2021] [Accepted: 03/29/2021] [Indexed: 11/17/2022] Open
Abstract
Parasitic and amphizoic amoebae are ubiquitous and can affect a huge variety of hosts, from invertebrates to humans, and fish are not an exception. Most of the relationships between amoebae and fish are based on four different types: ectocommensals, ectoparasites, endocommensals and endoparasites, although the lines between them are not always clear. As ectocommensals, they are located specially on the gills and particularly the amphizoic Neoparamoeba perurans is the most relevant species, being a real pathogenic parasite in farmed salmon. It causes amoebic gill disease, which causes a progressive hyperplasia of epithelial cells in the gill filaments and lamellae. Nodular gill disease is its analogue in freshwater fish but the causative agent is still not clear, although several amoebae have been identified associated to the lesions. Other species have been described in different fish species, affecting not only gills but also other organs, even internal ones. In some cases, species of the genera Naegleria or Acanthamoeba, which also contain pathogenic species affecting humans, are usually described affecting freshwater fish species. As endocommensals, Entamoebae species have been described in the digestive tract of freshwater and marine fish species, but Endolimax nana can reach other organs and cause systemic infections in farmed Solea senegalensis. Other systemic infections caused by amoebae are usually described in wild fish, although in most cases these are isolated cases without clinical signs or significance.
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English CJ, Lima PC. Defining the aetiology of amoebic diseases of aquatic animals: trends, hurdles and best practices. DISEASES OF AQUATIC ORGANISMS 2020; 142:125-143. [PMID: 33269724 DOI: 10.3354/dao03537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Disease caused by parasitic amoebae impacts a range of aquatic organisms including finfish, crustaceans, echinoderms and molluscs. Despite the significant economic impact caused in both aquaculture and fisheries, the aetiology of most aquatic amoebic diseases is uncertain, which then affects diagnosis, treatment and prevention. The main factors hampering research effort in this area are the confusion around amoeba taxonomy and the difficulty proving that a particular species causes specific lesions. These issues stem from morphological and genetic similarities between cryptic species and technical challenges such as establishing and maintaining pure amoeba cultures, scarcity of Amoebozoa sequence data, and the inability to trigger pathogenesis under experimental conditions. This review provides a critical analysis of how amoebae are commonly identified and defined as aetiological agents of disease in aquatic animals and highlights gaps in the available knowledge regarding determining pathogenic Amoebozoa.
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Affiliation(s)
- Chloe J English
- CSIRO Agriculture and Food, Livestock and Aquaculture, Queensland Bioscience Precinct, St. Lucia, QLD 4067, Australia
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Jensen HM, Karami AM, Mathiessen H, Al-Jubury A, Kania PW, Buchmann K. Gill amoebae from freshwater rainbow trout (Oncorhynchus mykiss): In vitro evaluation of antiparasitic compounds against Vannella sp. JOURNAL OF FISH DISEASES 2020; 43:665-672. [PMID: 32291787 DOI: 10.1111/jfd.13162] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 06/11/2023]
Abstract
Gill parasitic infections challenge farming of rainbow trout (Oncorhynchus mykiss, Walbaum) in freshwater facilities. Apart from flagellates (Ichthyobodo, (Pinto) and ciliates (Ichthyophthirius (Fouquet), Ambiphrya (Raabe), Apiosoma (Blanchard), Trichodinella (Sramek-Husek) and Trichodina (Ehrenberg)), we have shown that amoebae are prevalent in Danish trout farms. Gills were isolated from farmed rainbow trout in six fish farms (conventional and organic earth pond and recirculated systems) and placed on non-nutrient agar (NNA) moistened with modified Neff's amoeba saline (AS) (15°C). Gill amoebae from all examined fish colonized the agar and were identified based on morphological criteria showing species within the genera Trinema (Dujardin) (family Trinematidae), Vannella (Bovee) (family Vannellidae). In addition, hartmannellid amoebae were recorded. We established a monoculture of Vannella sp., confirmed the genus identity by PCR and sequencing and performed an in vitro determination of antiparasitic effects (dose-response studies) of various compounds including sodium chloride (NaCl), hydrogen peroxide, peracetic acid, formalin, aqueous garlic and oregano extracts and a Pseudomonas H6 surfactant. All amoebae were killed in concentrations of 16.90 mg/ml (garlic), 17.90 mg/ml (oregano), NaCl (7.5 mg/ml), hydrogen peroxide (100 µg/ml), peracetic acid (0.03 µg/ml), formaldehyde (25 µg/ml) and the Pseudomonas H6 surfactant (250 µg/ml).
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Affiliation(s)
- Hannah Malene Jensen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Asma Mohammad Karami
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Heidi Mathiessen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Azmi Al-Jubury
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Per Walter Kania
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Kurt Buchmann
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
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