Relationship Between Red Vent Syndrome and Anisakid Larvae Burden in Wild Atlantic Salmon (Salmo Salar)

Larrat, Sylvain; Bouchard, Francis; Séguin, Guylaine; Lair, Stéphane

doi:10.7589/2011-10-299

Cited by 6 publications

(11 citation statements)

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“…Moreover, total larval loads relative to tissue weights in the vent region were shown to be independent of the pattern of visceral infestation in all fish. This coincides with reports by Larrat et al (2013) who noted that the odds of having RVS significantly increased with the number of 1 0 0 0 3 3 1 0 83 54 144 2 0 2 1 0 1 0 1 11 22 38 3 0 0 0 0 0 0 0 35 33 68 4 2 2 2 1 0 2 0 22 12 43 5 1 0 0 1 0 0 0 51 21 74 6 5 0 0 0 1 0 1 27 30 64 7 0 0 0 0 0 0 1 31 14 46 8 0 2 1 5 5 1 0 22 37 73 9 0 0 1 0 0 0 0 13 18 32 larvae per gram of tissue in this area. Larrat et al (2013) in a larger study on Atlantic salmon from Canadian rivers also reported a lack of correlation of RVS severity and fish length.…”

Section: Discussionsupporting

confidence: 94%

Quantification and distribution ofAnisakis simplexsensu stricto in wild, one sea winter Atlantic salmon,Salmo salar, returning to Scottish rivers

et al. 2014

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Quantification and distribution of Anisakis simplex sensu stricto in wild, one sea winter Atlantic salmon, Salmo salar, returning to Scottish rivers patricia noguera, campbell pert, catherine collins, nichola still and david bruno Red vent syndrome (RVS) has previously been reported in returning wild Atlantic salmon, Salmo salar from Canada, Iceland, Ireland, Norway and the UK. Affected fish show reddening and swelling in the perianal/vent area, with scale loss, ulceration and bleeding in severe cases. Studies in the UK and elsewhere report the condition to be induced by Anisakis simplex sensu stricto (s.s.) larvae. This parasite, commonly reported in several marine fish species, is typically found in the body cavity and the skeletal muscle, but has recently been reported within the vent tissues of salmon. This latter finding may reflect greater efforts in examining this body portion due to current awareness of the parasite presence in this atypical location. Based on clinical observations, affected fish are classified into three categories according to the severity of the external lesions, but quantification of the vent parasite numbers in relation to the categories, and assessment of the relative importance of this area as a site of infestation, are missing to date. This investigation aimed to provide data on parasite number and distribution in the viscera, skeletal muscle, peduncle and vent area and to confirm the identity of the larvae found in the vent and the viscera. The study showed the perianal/vent region harbours the highest total number of A. simplex larvae per fish and, proportionally to fish biomass, is the most heavily infested body location irrespective of external severity levels of RVS.

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Section: Discussionsupporting

confidence: 94%

Quantification and distribution ofAnisakis simplexsensu stricto in wild, one sea winter Atlantic salmon,Salmo salar, returning to Scottish rivers

et al. 2014

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“…As the presence of Anisakis sp. larvae in the vent region has been shown to increase the likelihood of RVS symptoms [8], the significant increase in A. simplex (s.l.) intensity over the last 50 years is likely to have triggered the infection of the vent region, and the emergence and increasing prevalence of RVS in populations of Atlantic salmon.…”

Section: Discussionmentioning

confidence: 99%

“…larvae have been genetically assigned to A. simplex (s.s.) [5,6]. Characterised by bleeding, swollen, and haemorrhagic vents [5], RVS has subsequently been recorded throughout populations of Atlantic salmon in the North Atlantic [6][7][8]. The 'hyper-infestation' of the vent region by A. simplex (s.s.) had not been previously recorded in Atlantic salmon or any other fish host of anisakid larvae [5] and has been suggested to be a result of increasing intensities of A. simplex (s.s.) in Atlantic salmon [9].…”

mentioning

confidence: 99%

“…The 'hyper-infestation' of the vent region by A. simplex (s.s.) had not been previously recorded in Atlantic salmon or any other fish host of anisakid larvae [5] and has been suggested to be a result of increasing intensities of A. simplex (s.s.) in Atlantic salmon [9]. Additionally, the presence of L3 in the vent has been demonstrated to increase the likelihood of RVS symptoms [8].…”

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confidence: 99%

“…warm water copepods [14], and an increase in the occurrence of warm water cetacean species in Scotland [15] have the potential to significantly affect A. simplex (s.s.) abundance and introduce other Anisakis species in coastal waters around Scotland through their roles in transmission, and reproductive capacity of Anisakis, respectively. Furthermore, with Atlantic salmon being an opportunistic feeder [16], differences in food availability and food web structure in common feeding grounds can have direct influences on levels of parasite abundance [8,17].…”

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confidence: 99%

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Increasing intensities of Anisakis simplex third-stage larvae (L3) in Atlantic salmon of coastal waters of Scotland

et al. 2020

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Background: Red Vent Syndrome (RVS), a haemorrhagic inflammation of the vent region in Atlantic salmon, is associated with high abundance of Anisakis simplex (s.s.) third-stage larvae (L3) in the vent region. Despite evidence suggesting that increasing A. simplex (s.s.) intensity is a causative factor in RVS aetiology, the definitive cause remains unclear. Methods:A total of 117 Atlantic salmon were sampled from commercial fisheries on the East, West, and North coasts of Scotland and examined for ascaridoid parasites. Genetic identification of a subsample of Anisakis larvae was performed using the internal transcribed spacer (ITS) region of ribosomal DNA. To assess the extent of differentiation of feeding grounds and dietary composition, stable isotope analysis of carbon and nitrogen was carried out on Atlantic salmon muscle tissue. Results:In the present study, the obtained ITS rDNA sequences matched A. simplex (s.s.) sequences deposited in GenBank at 99-100%. Not all isolated larvae (n = 30,406) were genetically identified. Therefore, the morphotype found in this study is referred to as A. simplex (sensu lato). Anisakis simplex (s.l.) was the most prevalent (100%) nematode with the highest mean intensity (259.9 ± 197.3), in comparison to Hysterothylacium aduncum (66.7%, 6.4 ± 10.2) and Pseudoterranova decipiens (s.l.) (14.5%, 1.4 ± 0.6). The mean intensity of A. simplex (s.l.) represents a four-fold increase compared to published data (63.6 ± 31.9) from salmon captured in Scotland in 2009. Significant positive correlations between A. simplex (s.l.) larvae intensities from the body and the vent suggest that they play a role in the emergence of RVS. The lack of a significant variation in stable isotope ratios of Atlantic salmon indicates that diet or feeding ground are not driving regional differences in A. simplex (s.l.) intensities. Conclusions:This paper presents the most recent survey for ascaridoid parasites of wild Atlantic salmon from three coastal regions in Scotland. A significant rise in A. simplex (s.l.) intensity could potentially increase both natural mortality rates of Atlantic salmon and possible risks for salmon consumers due to the known zoonotic role of A. simplex (s.s.) and A. pegreffii within the A. simplex (s.l.) species complex.

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Metazoan Diseases

Hadfield

2021

Clinical Guide to Fish Medicine

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Relationship Between Red Vent Syndrome and Anisakid Larvae Burden in Wild Atlantic Salmon (Salmo Salar)

Cited by 6 publications

References 11 publications

Quantification and distribution ofAnisakis simplexsensu stricto in wild, one sea winter Atlantic salmon,Salmo salar, returning to Scottish rivers

Quantification and distribution ofAnisakis simplexsensu stricto in wild, one sea winter Atlantic salmon,Salmo salar, returning to Scottish rivers

Increasing intensities of Anisakis simplex third-stage larvae (L3) in Atlantic salmon of coastal waters of Scotland

Metazoan Diseases

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