Tissue distribution of Anisakis simplex larvae (Nematoda; Anisakidae) in wild Atlantic salmon, Salmo salar, from the Drammenselva river, south-east Norway (original) (raw)
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Journal of Fish Diseases, 2014
One hundred farmed Atlantic salmon, Salmo salar L., were examined for the presence of nematodes by digestion of tissue in HCl-pepsin solution. All fish were sampled from one cage in a fish farm on the Norwegian south-west coast. Fifty harvest quality salmon, that is, salmon for human consumption (mean 5.4 kg, variation 3.0 -7.6 kg), were sampled at the processing line while 50 salmon runts (mean 1.1 kg, variation 0.4-1.8 kg), discarded due to poor performance, were sampled from the discard bin after the grading station. Runts are individual fish with clear signs of poor performance over time and abnormal appearance and are thus not processed for human consumption. No nematodes were found in the musculature or viscera of the 50 harvest quality salmon. In total, 75 nematodes were found in 10 (20%) of the runts; 53 nematodes in the viscera and 22 in the musculature. Nematodes in the musculature were identified as Anisakis simplex (Rudolphi, 1809 det. Krabbe, 1878), while nematodes in the viscera were identified as A. simplex and Hysterothylacium aduncum (Rudolphi, 1802).
Diseases of Aquatic Organisms, 2008
Wild Atlantic salmon Salmo salar with swollen and/or bleeding vents (red vent syndrome) have been observed in rivers across England and Wales. Low numbers of salmon with this condition have previously been recorded, but reports have increased in 2006 and 2007. Affected and non-affected salmon were sampled from fish traps and their vent pathology was examined. Third stage larvae of the nematode Anisakis simplex sensu lato were observed in the tissue surrounding the vent in all affected fish. Histology of the vent showed gross lesions with an inflammatory response associated with non-encapsulated nematode worms in the connective tissue and skeletal muscle. The presence of the parasite in the unusual location of the vent areas, with associated haemorrhaging, is possibly a new emerging pathological association with the nematode A. simplex infection in Atlantic salmon. The reason for this unusual tissue tropism by larval A. simplex and the significance on already depleted salmon stocks are currently unknown.
Comparative infectivity of three larval nematode species in three different salmonids
Parasitology Research, 2013
Host specificity of parasites may depend both on ecological and physiological factors. Basic descriptions of the susceptibility/resistance of fish to specific nematodes are needed in order to reveal mechanisms in the host-parasite relation. Rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), and Atlantic salmon (Salmo salar) were orally infected with larval stages of three different anisakid nematodes-Hysterothylacium aduncum, Contracaecum osculatum, and Anisakis simplex-and parasite survival and location was subsequently recorded for up to 14 days post infection (dpi). H. aduncum was most prevalent and numerous in brown trout 2 dpi, but a large proportion of the worms were recovered dead. No tissue penetration was observed. Rainbow trout exhibited the highest susceptibility to C. osculatum larvae at 2, 7, and 14 dpi. Mean intensities and mean abundances were lower in brown trout and salmon at all time points. The pyloric cecum was penetrated in rainbow trout on two occasions. A. simplex larvae established more successfully in salmon compared to rainbow trout; brown trout exhibited the highest natural resistance. Mean intensity and mean abundance was highest in rainbow trout at 2 and 7 dpi, but not after 14 days. A range of tissues, including muscle and liver, were found penetrated by larvae, but the pyloric ceca were the preferred microhabitat for Anisakis in both rainbow trout and salmon. It can be concluded that closely related salmonids differ in susceptibility towards different anisakid larvae and these parasites select different microhabitats in the hosts. The physiological basis for this specificity is discussed.
Parasitology research, 2010
The prevalence of infection and the identification of anisakid larvae in chum salmon (Oncorhynchus keta) from the Namdae River, the east coast of Korea, were investigated. In total, 8,358 larvae were collected from 120 fish samples (male = 58 fish, female = 62 fish) in 2008. Fish samples were collected during October and November 2008. All the chum salmon samples (120/120, 100%) caught were infected with anisakid larvae with a high intensity (69.65±48.58 larvae/host). They were mostly found in muscles (98.00%). Based on the morphological and the molecular analysis of PCR-RFLP and sequencing of mitochondrial DNA cox2 gene markers, these nematodes were identified as Anisakis simplex (sensu stricto) third-stage larvae. This is the first report on the molecular identification of anisakid worms from salmonid fishes in Korea. The high occurrence of anisakid worms in chum salmon may pose considerable food safety problems if they were consumed as raw or undercooked, although their commercial value is relatively lower than other salmonid species.
Parasitology International, 2011
Anisakis pegreffii Experimental infection Oncorhynchus mykiss Rainbow trout Paralichthys olivaceus Olive flounder Site of infection The third-stage larvae of Anisakis simplex sensu lato (s.l.) are found in many marine fishes. To ensure food safety, it is important to determine whether these larvae are present in the body muscle of commercial fish species. However, there is little information regarding the tissue specificity of Anisakis and two of its sibling species, A. simplex sensu stricto (s.s.) and Anisakis pegreffii, that are common in marine fish in Japanese waters. We orally challenged rainbow trout (Oncorhynchus mykiss (Walbaum)), and olive flounder (Paralichthys olivaceus (Temminck and Schlegel)) with L3 larvae of these two sibling species and monitored infection for 5 weeks. In rainbow trout, A. simplex s.s., but not A. pegreffii larvae, migrated into the body muscle. A small number of freely moving A. pegreffii larvae were recovered within the body cavity. In olive flounder, A. simplex s.s. larvae were found in both the body cavity and body muscle. A. pegreffii larvae were found only in the body cavity and primarily encapsulated in lumps. Our results indicate that there are differences in the sites of infection and host specificity between the two sibling species of A. simplex s.l.
Parasitology Research, 2011
The aim of the present study was to conduct, in southern Australian waters, a preliminary epidemiological survey of five commercially significant species of fish (yellow-eye mullet, tiger flathead, sand flathead, pilchard and king fish) for infections with anisakid nematodes larvae using a combined morphological-molecular approach. With the exception of king fish, which was farmed and fed commercial pellets, all other species were infected with at least one species of anisakid nematode, with each individual tiger flathead examined being infected. Five morphotypes, including Anisakis, Contracaecum type I and II and Hysterothylacium type IV and VIII, were defined genetically using mutation scanning and targeted sequencing of the second internal transcribed spacer of nuclear ribosomal DNA. The findings of the present study provide a basis for future investigations of the genetic composition of anisakid populations in a wide range of fish hosts in Australia and for assessing their public health significance.