Negligible risk of zoonotic anisakid nematodes in farmed fish from European mariculture, 2016 to 2018

Abstract

Background The increasing demand for raw or undercooked fish products, supplied by both aquaculture and fisheries, raises concerns about the transmission risk to humans of zoonotic fish parasites. This has led to the current European Union (EU) Regulation No 1276/2011 amending Annex III of Regulation (EC) No 853/2004 and mandating a freezing treatment of such products. Zoonotic parasites, particularly anisakid larvae, have been well documented in wild fish. Data on their presence in European aquaculture products, however, are still scarce, except for Atlantic salmon (Salmo salar), where the zoonotic risk was assessed as negligible, exempting it from freezing treatment. Aim To evaluate the zoonotic Anisakidae parasite risk in European farmed marine fish other than Atlantic salmon. Methods From 2016 to 2018 an observational parasitological survey was undertaken on 6,549 farmed fish including 2,753 gilthead seabream (Sparus aurata), 2,761 European seabass (Dicentrarchus labrax) and 1,035 turbot (Scophthalmus maximus) from 14 farms in Italy, Spain and Greece. Furthermore, 200 rainbow trout (Oncorhynchus mykiss) sea-caged in Denmark, as well as 352 seabream and 290 seabass imported in Italy and Spain from other countries were examined. Fish were subjected to visual inspection and candling. Fresh visceral organs/fillet samples were artificially digested or UV pressed and visually examined for zoonotic anisakid larvae. Results No zoonotic parasites were found in any of the fish investigated. Conclusions The risk linked to zoonotic Anisakidae in the examined fish species from European mariculture appears negligible. This study laid the groundwork for considerations to amend the current EU regulation.

A case study on farmed European seabass and gilthead seabream in central Italy: The negligible parasitological risk of nematode larvae paves the way for the freezing derogation

“…The absence of ascaridoid nematodes in farmed gilthead seabream and European seabass analysed during self-control procedures from 2016 to 2019 agrees with the results obtained for farmed species from the bibliographic analysis (Table 2). In fact, the only ascaridoid nematodes found in Mediterranean Sea in the examined species were: two larvae of A. pegreffii in 68 European seabass from Greek farm (Cammilleri et al, 2018), 1 larva of H. fabri in 140 European seabass from Italy (Fioravanti et al, 2021) and Contracaecum sp. (prevalence around 15%) in both species from Sardinia (Salati et al, 2013).…”

“…in gilthead seabream (P = 10.8%). Therefore, the available data suggest a low to negligible prevalence as regards these parasites confirming what already reported for other farmed species (Asociación Empresarial de Productores de Cultivos Marinos, 2012;Brooker al., 2016;EFSA;2010;Fioravanti et al, 2021;Peñalver et al, 2010;Roiha et al, 2020). Furthermore, visceral localization in European seabass and gilthead seabream is preferred than muscular tissue (Table 1 in Guardone et al, 2020 and Table 3).…”

“…In the work of Rohia et al (2020), a sample of 1000 specimens were estimated as sufficient for assessing a prevalence of 0.05% in a population of 20 million fish specimens. Similarly, in the work of Fioravanti et al (2021) a sampling plan with a confidence level of 99% and a margin of error (MoE) of 4-8% was used and a samples of 1032 fish per species (least 258 fish per farm) was considered to be statistically significant for obtaining prevalence estimates. Thus, applying an analogous approach, the number of specimens analysed in the self-control activities by the FBOs would be largely sufficient to found such very low prevalence.…”

“…For other farmed species, such as gilthead seabream (Sparus aurata), turbot (Scophtalmus spp. ), umbrine (Umbrina cirrosa) and European seabass (Dicentrarchus labrax), the risk of contracting anisakiasis was estimated to be from extremely low to negligible (Asociación Empresarial de Productores de Cultivos Marinos, 2012;Brooker al., 2016;Fioravanti et al, 2021;Peñalver et al, 2010). However, derogations from the preventive freezing has not been authorized for these latter species, so far.…”

“…The bioaccumulation of parasites in runts was observed in Atlantic salmon and in rainbow trout (Levsen and Maage;Mo et al, 2014;Roiha et al, 2020). Runts seem therefore to be the most exposed to contamination as they are pushed, to survive, to the opportunistic predation of the wild species that have penetrated the cages (Fioravanti et al, 2021).…”