Search results for "Fish diseases"
showing 10 items of 232 documents
Minor environmental concentrations of antibiotics can modify bacterial virulence in co-infection with a non-targeted parasite.
2018
Leakage of medical residues into the environment can significantly impact natural communities. For example, antibiotic contamination from agriculture and aquaculture can directly influence targeted pathogens, but also other non-targeted taxa of commensals and parasites that regularly co-occur and co-infect the same host. Consequently, antibiotics could significantly alter interspecific interactions and epidemiology of the co-infecting parasite community. We studied how minor environmental concentrations of antibiotic affects the co-infection of two parasites, the bacterium Flavobacterium columnare and the fluke Diplostomum pseudospathaceum , in their fish host. We found that antibiotic in …
The influence of food competition and host specificity on the transmission of Triaenophorus crassus (Cestoda) and Cystidicola farionis (Nematoda) to …
2000
Abstract As a superior competitor for planktonic food, vendace ( Coregonus albula ), when abundant, is expected to displace whitefish ( Coregonus lavaretus ) from feeding on plankton and to force it to rely more on benthic food. The predicted result would be a reduced abundance of the copepod-transmitted cestode Triaenophorus crassus in whitefish, but an increase in the abundance of the nematode Cystidicola farionis transmitted via benthic amphipods. We studied the occurrence of both parasites in whitefish during 1991–1996 in three interconnected areas at Lake Saimaa, Finland, where the densities of the vendace stocks varied due to natural fluctuation in year-class strengths. In accordance …
Behavioural adaptations of argulid parasites (Crustacea: Branchiura) to major challenges in their life cycle.
2015
Fish lice (Argulus spp.) are obligate ectoparasites, which contrary to most aquatic parasites, retain the ability to swim freely throughout the whole of their life. In fish farms, they can quickly increase in numbers and without effective control cause argulosis, which results in the reduced growth and survival of their fish hosts. The morphology of Argulus spp, including their sensory organs, is suitable for both parasitism and free-swimming. By spending a considerable amount of time away from their host, these parasites risk being excessively dispersed, which could endanger mating success. Here we present a review of recent studies on the behaviour of Argulus spp, especially the aggregati…
Anisakid larvae in the musculature of the Argentinean hake, Merluccius hubbsi
2000
We report the infection levels of third-stage anisakid larva in the muscle of the Argentinean hake, Merluccius hubbsi, in relation to fish size and location in the musculature. The musculature of 42 hake was separated into hypaxial (ventral) and epiaxial (dorsal) parts and surveyed for nematode larvae. Two anisakid species were detected: Anisakis sp. (prevalence, 52.4%; mean +/- SD abundance, 1.2 +/- 1.7) and Pseudoterranova sp. (prevalence, 9.5%; mean +/- SD abundance, 0.2 +/- 0.7). Since the fish were gutted after capture, the occurrence of anisakids in the flesh indicates that the worms had migrated into the muscle before capture. The number of Anisakis sp. in muscle was not correlated w…
The widespread presence of a family of fish virulence plasmids in Vibrio vulnificus stresses its relevance as a zoonotic pathogen linked to fish farms
2021
Vibrio vulnificus is a pathogen of public health concern that causes either primary septicemia after ingestion of raw shellfish or secondary septicemia after wound exposure to seawater. In consequence, shellfish and seawater are considered its main reservoirs. However, there is one aspect of its biology that is systematically overlooked: its association with fish in its natural environment. This association led in 1975 to the emergence of a zoonotic clade within phylogenetic lineage 2 following successive outbreaks of vibriosis in farmed eels. Although this clade is now worldwide distributed, no new zoonotic clades were subsequently reported. In this work, we have performed phylogenetic, ge…
Presence of a capsule in Vibrio vulnificus biotype 2 and its relationship to virulence for eels
1993
Strains of Vibrio vulnificus biotype 2, isolated from internal organs of diseased European eels as pure cultures of opaque cells, together with some reference strains from Japanese eels, were used in this study. Spontaneous translucent-phase variants were obtained from the corresponding parent strains and compared for a variety of phenotypic traits related to virulence for eels. The rate of colony dissociation from opaque to translucent cells was higher (around 10(-2)) than that observed for translucent to opaque cells (10(-3) to 10(-4)). Electron microscopy with ruthenium red revealed the presence of a capsule of variable thickness on opaque cells, whereas translucent-type colonies had no …
A link between ectoparasite infection and susceptibility to bacterial disease in rainbow trout
2006
Rainbow trout, Oncorhynchus mykiss, were infected concomitantly with Argulus coregoni and Flavobacterium columnare and their survival was compared with that of fish infected with either the parasite or the bacterium alone. The mortality of fish challenged with A. coregoni was negligible while infection with F. columnare alone led to significantly lower survival. However, compared with single infections, the mortality was significantly higher and the onset of disease condition was earlier among fish, which were concomitantly infected by A. coregoni and F. columnare. This data presents, for the first time, experimental support for the hypothesis that an ectoparasite infection increases suscep…
Biochemical and molecular characterization of three serologically different Vibrio harveyi strains isolated from farmed Dicentrarchus labrax from the…
2022
AbstractVibrio harveyi is recognized as one of the major causes of vibriosis, a disease that threatens the long-term sustainability of aquaculture. Current research shows that the Mediterranean strains of V. harveyi are serologically heterogeneous, though research comparing the traits of different strains is scarce. This study aims to describe the biochemical, physiological and genetic characteristics of three serologically different strains of V. harveyi isolated from farmed European Sea bass (Dicentrarchus labrax) from the Adriatic Sea. A total of 32 morphological and biochemical markers were examined and, the susceptibility to 13 antimicrobials tested, and then compared the results of hi…
HELMINTH ASSEMBLAGES OF WHITEFISH (COREGONUS LAVARETUS) IN INTERCONNECTED LAKES: SIMILARITY AS A FUNCTION OF SPECIES SPECIFIC PARASITES AND GEOGRAPHI…
2004
This article examined the composition of parasite assemblages of whitefish (Coregonus lavaretus) in 8 interconnected lakes in northeastern Finland and evaluated the role of coregonid specific parasites and the geographical distance between populations in determining the similarity of the assemblages. Parasite assemblages were compared using the Jaccard qualitative similarity index and a quantitative similarity index and by incorporating the allogenic-autogenic species concept and the effects of 2 corresponding measures of geographical distance between the lakes. The majority of the parasite species found (10 of 14) were specific to salmonids. Similarity of assemblages of autogenic parasites…
Susceptibility of eye fluke-infected fish to predation by bird hosts.
2005
Host manipulation by trophically transmitted parasites may predispose infected hosts to predation and in this way enhance parasite transmission. In most study systems, however, the evidence comes from laboratory studies, and therefore knowledge of the effect of manipulation on parasite transmission efficiency in the wild is still limited. Here we examined the effect ofDiplostomum spathaceum(Trematoda) eye flukes on the susceptibility of fish intermediate hosts to predation by bird definitive hosts. Our earlier studies have shown that the parasite alters fish phenotype and increases their susceptibility to artificial predation under laboratory conditions. In the present field study, we allow…