Infections In Marine Fish Research Articles

Description of three new species of Kudoa Meglitsch, 1947 (Myxozoa: Multivalvulida) in commercial marine fishes from southern China, and new host records.

Multivalvulidan myxosporeans (Multivalvulida) of the genera Unicapsula Davis, 1924 and Kudoa Meglitsch, 1947 are mostly causative agents of latent and imperceptible infection in marine fishes. However, they are sometimes incriminated in causing post-mortem myoliquefaction or unsightly cyst formation in commercial fish. Despite the great commercial impacts of multivalvulidan infection, the biodiversity, host range and epidemiology of multivalvulidan species remain to be explored further, including infection of alternative annelid hosts. Therefore, this study aimed to identify multivalvulidan species and their host and/or distribution records in commercial fishes in China. Multivalvulidan infection was detected in ten commercial fish species of seven families from the South and East China Seas (Northwest Pacific Ocean) and the Eastern Central Atlantic Ocean (an imported Dagetichthys lusitanicus [de Brito Capello]). Based on morphological and molecular-genetic analyses of their small and large subunit of ribosomal RNA genes, five new host and/or geographical distribution records for five fish species are presented, and three new species in five fish species are described, namely Kudoa neoscomberomori sp. n. in Scomberomorus commerson (Lacépède); Kudoa pilosa sp. n. in Helicolenus hilgendorfi (Döderlein) (type host) and Sebastiscus tertius (Barsukov et Chen); and Kudoa tumidisporica sp. n. in Photopectoralis bindus (Valenciennes) (type host) and Nuchequula nuchalis (Temminck et Schlegel). This study provides new data on multivalvulidan diversity in the ocean ecosystem.

Mass mortality associated with carpione rhabdovirus in golden pompano (Trachinotus ovatus) in China: First report

From August to November 2023, a severe epizootic outbreak occurred in an offshore cultured golden pompano (Trachinotus ovatus) population in Zhanjiang City, Guangdong Province, China, resulting in a cumulative mortality rate of 65–82 %. The diseased fish showed clinical signs of lethargy, anorexia, whirling movements, and hemorrhage at the base of the fins and in the upper and lower jaws before mass mortality. A rhabdovirus strain, designated as CARPV2023, was successfully isolated using fathead minnow (FHM) cells. The cytopathic effects of the tissue filtrate from the diseased golden pompano on FHM and epithelioma papulosum cyprini (EPC) cell monolayers were characterized by rounded cells, grape-like cluster formation, detachment, and lysis. Histopathology revealed congestion, hemorrhage, and necrosis in the spleen, liver, trunk kidney, and intestinal tissues of naturally and experimentally infected golden pompanos. Electron microscopy showed that bullet-shaped viral particles, measuring 183.5–217.6 nm in length and 57.3–82.7 nm in width, budded from the cell membrane or aggregated around the infected FHM cells. The virus remained stable for 7 d at 4–33 °C and replicated optimally at 28 °C. Whole-genome sequencing and subsequent phylogenetic analysis further indicated that the carpione rhabdovirus (CARPV)2023 strain is a new carpione rhabdovirus, and is related to novirhabdoviruses, however, is thus far unclassified. A specific nested reverse transcription-polymerase chain reaction assay confirmed the presence of CARPV in the affected golden pompano. Significantly higher mortality was observed in challenged golden pompanos than that in the controls through intraperitoneal injection and immersion infection. Fluorescence in situ hybridization showed showed positive reactions for RNA in multiple tissues (liver, spleen, trunk kidney, brain, heart, gill, and muscle) from infected fish. The highest expression level was confirmed in the spleen through qPCR. This is the first study to report natural CARPV infections in marine fish.

Prevalence of Anisakise infections in marine fishes in Eastern Fujian Fishing Ground of Fujian Province

To investigate the prevalence of Anisakis infection in marine fishes in Eastern Fujian Fishing Ground of Fujian Province, so as to provide insights into the development of the anisakiasis control strategy. Marine fish samples were randomly collected from Jiaocheng District, Fuding City and Xiapu County around Eastern Fujian Fishing Ground in Fujian Province from September to December, 2021. All fishes were dissected, and the abdominal contents were collected. Parasites were sampled under a stereomicroscope and the Anisakis species were identified through morphology. The prevalence and intensity of Anisakis infections were calculated. A total of 177 marine fishes belonging to 24 species were dissected, and Anisakis was detected in 73 marine fishes (41.2%) belonging to 16 species (66.7%), with a mean infection intensity of 14.3 parasites per fish. High prevalence of Anisakis infection was found in Ilisha elongata (5/5), Miichthys miiuy (3/3), Plectorhynchus cinctus (2/2), Scomberomorus niphonius (12/13), Trichiurus lepturus (19/23), Pennahia argentata (6/11) and Ditrema temmincki (14/27), with mean infection intensities of 9.2, 2.7, 4.5, 10.9, 39.2, 4.5 parasites per fish and 2.1 parasites per fish. The Anisakis larvae were characterized as Anisakis and Hysterothylacium. High prevalence of Anisakis infection is detected in marine fishes in Eastern Fujian Fishing Ground of Fujian Province. The health education pertaining to food health is required to be reinforced to prevent the development of human anisakiasis.

Effect of Environmental Factors on the Intensity of Nematode Infection in Marine Fishes of Visakhapatnam, A.P, India

Effect of Environmental Factors on the Intensity of Nematode Infection in Marine Fishes of Visakhapatnam, A.P, India

Investigation of Anisakis infections in market-available marine fish in Dongtai City

To understand the situation of Anisakis infection of in market-available marine fish in Dongtai City, so as to provide the evidence for the assessment of the risk of human Anisakis infections. Raw and fresh marine fish caught in the sea of Dongtai City for sale were collected in 2018. The fish were weighted and dissected for the identification of Anisakis, and the prevalence and intensity of Anisakis infections were calculated. In addition, the correlation between the weight of Anisakis-infected marine fish and the infection intensity of Anisakis was examined. There were four species of marine fish infected with Anisakis, including Trichiurus haumela, Scomberomorus niphonius, Pneumatophorus japonicus and Larimichthys polyactis. Among the 149 fish samples, there were 78 with Anisakis infections, with a prevalence rate of 52.35%. The prevalence of Anisakis infection was 100.00% (28/28), 30.00% (9/30), 0 (0/30), 53.33% (16/30) and 80.65% (25/31) in T. haumela, S. niphonius, cuttle fish, P. japonicus and L. polyactis, respectively. A total of 1 049 Anisakis worms were collected, and the overall intensity of infection was 13.45 worms per fish. Spearman correlation analysis showed a positive correlation between the weight of T. haumela and the intensity of Anisakis infection (rs = 0.38, P = 0.047), and no correlation was found in other fish species. There is a high rate of Anisakis infection in marine fish along the offshore areas of Dongtai City. Intensification of health education is required and healthy and safe dietary habits are encouranged.

Characterization of Vibrio parahaemolyticus Infection in Gilthead Seabream (Sparus auratus) Cultured in Egypt

This study aimed to diagnose V. parahaemolyticus infection among cultured Gilthead Seabream from the Suez Canal area of Egypt. A total of 200 Gilthead Seabream fish samples were clinically examined for the presence of any abnormal external or internal clinical findings. Samples from internal organs of moribund fish were subjected to histopathological and microbiological examinations. Retrieved isolates were biochemically identified using API 20 E system then further confirmed by regular PCR. Antibiogram profiling of the retrieved isolates was also done. A sum of 64 V. parahaemolyticus isolates was retrieved from the examined moribund Gilthead seabream samples. A total of 18 (32.8%) of the retrieved isolates were positive for the Kanagawa phenomenon (KP+ve). An expected product with a length of 368 bp size bands was found from tested strains of toxR targeted gene. Further, the PCR amplification of pR72H target gene generated an expected product with a length of 387-bp. Most of the isolates showed resistance to Ampicillin (AMP 10μg) and Gentamycin (CN 10μg) with high sensitivity to Sulphamethoxazole/Trimethoprim (SXT 25μg). Pathologically, severe inflammatory reactions together with melanomacrophage center alterations were recorded within the examined splenic, hepatic, renal and branchial tissues. Ultimately, the current study emphasizes the critical fish health threats posed by V. parahaemolyticus with consequent impacts on human consumers. Thus, competent biosecurity strategies should be adopted to control Vibrio infection in marine fishes and to minimize the antimicrobial resistance hazards in mariculture.

Characterization of Vibrio Alginolyticus Infection in Gilthead Seabream (Sparus Auratus, L) Cultured in Egypt

The present study investigated Vibriosis in cultured Gilthead Seabream at the Suez Canal area, Egypt. Two hundred moribund fish samples subjected to clinical, microbiological and histopathological examinations. Retrieved isolates were biochemically identified using API 20 E system then confirmed by conventional PCR. Antibiogram profiling of the retrieved isolates was also done.Naturally infected fish showed severe ascites, hemorrhages and erosions in the skin and fins.A sum of 29 V. alginolyticus isolates were retrieved from the examined samples. Targeting 16SrRNA and groEl genes produce an expected product with a length of 336, 301bp size bands; respectively, were found from all tested strains of V. alginolyticus. The antibiogram profiling of V. alginolyticus isolates showed resistance to Ampicillin, Gentamycin followed by Ciprofloxacin with high sensitivity to Sulphamethoxazole/Trimethoprim and oxytetracycline. Histopathological alterations in the affected tissues showed, inflammatory reactions together with degenerative and /or necrotic changes in branchial, liver and kidney. Ultimately, the current study emphasizes the critical fish health threats posed by V. alginolyticus with subsequent influences on human. Thus, competent biosecurity strategies should be adopted to control Vibrio infection in marine fishes and to minimize the antimicrobial resistance hazards in mariculture.

Epidemical study of third stage larvae of Anisakis spp. infection in marine fishes in China from 2016 to 2017

BackgroundAnisakis, a genus of parasitic nematodes, can infect fish and potentially cause diseases in human. Yet it has not drawn public attention in China. It is urgent to conduct the first epidemical study on third stage larvae of Anisakis spp. infection in marine fishes across most coastal regions of China from 2016 to 2017. MethodsIn this study, 2422 samples of marine fishes were collected from eight coastal regions in China from 2016 to 2017. The third-stage larvae of Anisakis spp. were examined under a light microscope. The chi-square test, the Fisher's exact test and the logistic regression were applied in this study. ResultsThe infection rate was 28.70% (695/2422). Compared with live fish, the infection rate of fresh fish was higher at 31.88% (577/1810). Statistical analyses showed that there existed a significant difference in infection rate of different sampling months, which could be explained by fishing ban. ConclusionsThe result showed that sampling region, fish status, fish species and sampling month were the main factors influencing infection rate. Regulations or guidelines are urgent in China for the control of Anisakis spp. infection in marine fish.

Optimization of protectant, salinity and freezing condition for freeze-drying preservation of Edwardsiella tarda

Novel preservation condition without ultra-low temperature is needed for the study of pathogen in marine fishes. Freeze-drying is such a method usually used for preservation of terrigenous bacteria. However, studies using freeze-drying method to preserving marine microorganisms remain very limited. In this study, we optimized the composition of protectants during the freeze-drying of Edwardsiella tarda, a fish pathogen that causes systemic infection in marine fishes. We found that the optimal composition of protectant mixture contained trehalose (8.0%), skim milk (12.0%), sodium citrate (2.0%), serum (12.0%) and PVP (2.0%). Orthogonal and interaction analyses demonstrated the interaction between serum and skim milk or sodium citrate. The highest survival rate of E. tarda was observed when the concentration of NaCl was 10.0, 30.0 and between 5.0 and 10.0 g L−1 for preparing TSB medium, E. tarda suspension and protectant mixture, respectively. When E. tarda was frozen at −80°C or −40°C for 6 h, its survival rate was higher than that under other tested conditions. Under the optimized conditions, when the protectant mixture was used during freeze-drying process, the survival rate (79.63%–82.30%) of E. tarda was significantly higher than that obtained using single protectant. Scanning electron microscopy (SEM) image indicated that E. tarda was embedded in thick matrix with detectable aggregation. In sum, the protectant mixture may be used as a novel cryoprotective additive for E. tarda.

Larval Anisakid Infections in Marine Fish from Three Sea Areas of the Republic of Korea

The present study was performed to determine the infection status of anisakid larvae in marine fish collected from 3 sea areas of the Republic of Korea. Total 86 marine fish (8 species) collected from the East Sea (Goseong-gun, Gangwon-do), 171 fish (10 species) from the South Sea (Sacheon-si, Gyeongsangnam-do), and 92 fish (7 species) from the Yellow Sea (Incheon Metropolitan City) were examined by both naked eyes and artificial digestion method. Among the total of 349 fish examined, 213 (61.0%) were infected with 8 species of anisakid larvae, i.e., Anisakis simplex, 6 types of Contracaecum spp., and Raphidascaris sp., and the mean larval density was 13.8 per infected fish. Anisakid larvae were detected in 45 fish (52.3%) from the East Sea, 131 fish (76.6%) from the South Sea, and 37 fish (40.2%) from the Yellow Sea. The average numbers of larvae detected were 4.0, 16.6, and 15.9, respectively. Anisakis simplex larvae were detected in 149 fish (42.7%), and the mean larval density was 9.0 per infected fish. They were found in 26 fish (30.2%) collected from the East Sea, 96 fish (56.1%) from the South Sea, and 27 fish (29.3%) from the Yellow Sea. The average numbers of larvae detected were 2.9, 10.3, and 10.5, respectively. Conclusively, the present study suggests that the infection rate and density of anisakid larvae are more or less higher in the fish from the South Sea than those from the East Sea or the Yellow Sea.

Inflammation and Innate Immune Response Against Viral Infections in Marine Fish

Viral infections in fish are common in both natural and cultured fish populations and the spread of infectious disease is a serious threat to both natural ecosystems and commercial exploitations. A significant body of studies have addressed the host response to viral infection including the efficacy of DNA vaccines however we still have a fragmented vision of both pathologies associated with viral infection and the immune response to those across fish species. Many studies have concentrated upon freshwater fish including the zebrafish (Danio rerio) and the Rainbow trout (Oncorhynchus mykiss) whereas the majority of marine fish studies address the Atlantic salmon (Salmo salar). Here we provide a comprehensive review concentrating upon the salient pathological features of the most common viral infections including examples of the Betanodaviruses, Birnaviruses, Rhabdoviruses and the Isavirus in cultured fish with emphasis where possible upon non-salmonid cold water adapted marine species. In parallel we review the current state of the art mainly in reference to gene expression studies describing the host innate immune response concentrating upon the inflammatory response and its relationship toward anti-viral immunity in fish. Due to the complexity of the observed responses and the limitations of candidate gene expression studies to describe global biological processes, recent efforts in the use of microarray analysis for the study of the anti-viral response have been highlighted including members of the Pleuronectiform and the Perciform families. Finally we review the potential of the zebrafish to become a significant biological model in the elucidation of the molecular mechanisms underlying the piscine immune response to viral infection.

Kudoa iwatai and two novel Kudoa spp., K. trachuri n. sp. and K. thunni n. sp. (Myxosporea: Multivalvulida), from daily consumed marine fish in western Japan

Infection of marine fish by certain myxosporean species of the genus Kudoa results in unsightly cyst formation in the trunk muscle or post-mortem myoliquefaction, causing a great economic loss to aquaculture industries, capture fisheries, and fish dealers. In addition, consumers encountering unsightly Kudoa cysts in fish fillets believe them to be unknown foreign materials acquired during processing. To identify prevalent Kudoa spp. encountered in daily life by the Japanese population, fresh fish slices (sashimi) or fish fillets with whitish spots were collected during a 7-month period (May to December 2008) at local markets in the city of Yamaguchi, western Japan. Kudoa cysts were found in three Japanese seaperches (Lateolabrax japonicus), two black sea bream (Acanthopagrus schlegelii), two Japanese jack mackerel (Trachurus japonicus), and one albacore (Thunnus alalunga). Kudoa iwatai was identified in all the examined Japanese seaperch and black sea bream from Japan's Inland Sea, as assessed by morphology and genetic analysis of the 18S and 28S ribosomal RNA gene (rDNA). Kudoa trachuri n. sp. from two Japanese jack mackerel fished in the Japanese Sea off Nagasaki and Kudoa thunni n. sp. from one albacore fished in the Pacific Ocean had a spore, which was semiquadrate in shape in apical views and ovoid in lateral views, with four equal shell valves and drop-like polar capsules. Scanning electron microscopy revealed that these three Kudoa species had different types of small projections at the apex of each valve. The 18S and 28S rDNA sequences of K. trachuri n. sp. and K. thunni n. sp. were found to be closely related to those of Kudoa crumena; however, these sequences were distinct in each of the species, which additionally exhibited different morphological features.

A Review of Ichthyobodo Infection in Marine Fishes.

The ectoparasitic flagellate Ichthyobodo has been recorded from 25 species of marine fishes and 3 species of anadromous salmon in the Pacific Ocean, Atlantic Ocean, and adjacent seas ranging from the subarctic to tropical zones. With an increasing number of reports on the occurrence of Ichthyobodo in the marine environment, its origin and taxonomic status have been confused. The parasite from marine fishes is morphologically comparable to the freshwater parasite I. necator, which can survive and reproduce on anadromous salmon in seawater. It was assumed that the parasite on marine fish was transmitted from freshwater hosts. However, the marine parasite from Japanese flounder (Paralichthys olivaceus) andI. necatorfrom freshwater chum salmon (Oncorhynchus keta) were differentiated by their host specificity. The parasite has been found on pure marine fishes in offshore waters. Thus, Ichthyobodo on marine fishes may be regarded as a separate species from freshwater I. necator. The parasite infects the skin and gills of host fishes, causing severe epidermal hyperplasia and necrosis. Ichthyobodo infections caused moderate deaths in yearling Japanese flounders and tiger puffer (Takifugu rubripes), while the infections induced high mortalities among larvae of marine fishes such as Japanese flounders, gilthead sea bream (Sparus aurata), and rockfish (Sebastes schlegli). The most effective treatment for Ichthyobodo infections is a formalin bath, but alternative safe control methods should be established by future studies.

Metacercarial infection of marine fish by Labratrema minimus (Digenea, Bucephalidae): histo-cytological analysis of host-parasite relationship

Metacercarial infection of marine fish by Labratrema minimus (Digenea, Bucephalidae): histo-cytological analysis of host-parasite relationship

Studies on the morphology of Uronema marinum Dujardin (Ciliatea: Uronematidae) with a description of the histopathology of the infection in marine fishes

Abstract. A normally free‐living hymenostomatid ciliate was found to be the cause of heavy infections of gills, viscera and body muscle in Atlantic and Pacific marine fishes kept in the New York Aquarium. Of special interest is the fact that the parasites, usually with food vacuoles filled with blood cells and cellular debris, caused extensive damage to the body muscle; the other infected organs showed no characteristic tissue reactions. The immediate cause of death is attributed to the exceptional load of the parasite on the gills, thus interfering with normal respiratory function.The ciliate, isolated from a recent outbreak, is described in detail, and shows many characteristics of Uronema marinum Dujardin, a species that has been reported as free‐living in salt water; the form reported here differs from the type and other members included in this species, by the presence of less than three rows of bipolar meridians. This facultative parasite is described in detail and compared with other genera.

Infectivity of Trypanosoma murmanensis to leeches (Johanssonia sp.).

Experiments were designed to test the infectivity of trypomastigotes of Trypanosoma murmanensis to leeches at intervals after metatrypomastigotes had initiated infections in marine fish. Infectivity was determined by the presence of developmental stages in recently emerged leeches (Johanssonia sp.) that had fed on experimentally infected fish. A total of 1235 leeches were used in this study. The results indicate that the three morphotypes can initiate infections in leeches. Moreover, some trypanosomes are infective at least 24 h after transmission (16 (67%) leeches became infected). Few leeches acquired infections after feeding on infected winter flounder (Pseudopleuronectes americanus) between 2 and 12 days and on a cod (Gadus morhua) 4–5 days, but all those which fed 7 through 93 day s on five species of marine teleosts became infected. Some of the leeches transmitted infections to uninfected cod. It is believed that the leeches which harboured no developmental stages might not have ingested trypanosomes.