PROJECT AMBASSADOR OF November 2013
Dr Arne Levsen / National Institute of Nutrition and Seafood Research (Nasjonalt Institutt for Ernærings- og Sjømatforskning, NIFES), Norway
Dr. Arne Levsen is the leader of workpackage 2, which deals with parasite exposure assessment. The WP aims to provide comprehensive and comparable epidemiological data regarding zoonotic parasites in fish stocks from the major European fishing grounds, as well as in various fresh fish product imports on relevant European markets.
About Arne Levsen
His current research interest is on the life cycle of the marine parasites Anisakis simplex, especially focusing on the species’ phenotypic plasticity at the fish host level. In another cooperative project he studies the ecology incl. the life cycle, of the myxosporean parasite species Kudoa thyrsites in Atlantic mackerel.
Dr Levsen has since 2007 been an attending deputy member of the National committee for contagious diseases from food. During 2009-2010, and in 2011, he was a scientific expert member of two EFSA working groups under the BIOHAZ Panel; 1) on ‘Risk assessment of parasites in fishery products’, and 2) on ‘Fish parasites in the Baltic Sea’.
Dr. Levsen is providing some key answers about his work within the Parasite project
Why is epidemiological information relevant to address the risk arisen from the presence of zoonotic parasites in fish products?
Self-control programmes in the fish industry are hampered by the fact that the epidemiology of fish nematode parasites in European markets is not well-understood. The collection of systematic data on the complete life cycle, geographical and seasonal distribution, prevalence, intensity, and anatomical location of parasites of public health importance in wild caught stocks and fishery products is currently made on biased and opportunistic bases, with no time-series available nor any monitoring programs coordinated on a pan-European scale. A well designed systematic epidemiological survey of the ten economically most important fish species or stocks from four major fishing areas aims to provide the basis for analysing and modelling parasite prevalence. Besides the large scale of the survey in terms of geographical and temporal range as well as sample size and number of host species, an important advantage will be the use of the same nematode detection method by all surveyors to map the infection level and spatial distribution of anisakid larvae in the target fish species and fishing areas. This will reduce the effect of errors due to differences in detection efficiency and operator skills on the quality of data during sampling and registration.
Three of the fish species to be included in the survey, i.e. Atlantic mackerel, blue whiting and hake, occur and are commercially utilised in all major European fishing areas except the Baltic Sea. Thus, the epidemiological data to be obtained from these species and areas will be used to analyse the effect of specific habitat characteristics, geographical location/latitude and fish host migration on the diversity and distribution of anisakid species.
What fish species have been chosen to work with and why?
Parasitic nematode larvae are common in so to speak every marine fish species from all European fishing grounds. The parasite species of primary concern is Anisakis simplex, also known as the herring- or whale worm. While most of the Anisakis-larvae – regardless of host species – seem to lodge in or on the organs of the abdominal cavity of fish, some worms may migrate into the fish flesh, sometimes even deeply into the fillets. This behaviour, which makes both detection and removal of the parasites more difficult, is to blame for the attention the worms receive from consumers and public food safety authorities.
In a given fish, the majority of anisakid larvae are typically seen as greyish, flat and tight coils, measuring a few mm across. Larvae that reside in the fish flesh are very hard to detect by the naked eye since they are often transparent. Moreover, the larval occurrence in terms of their abundance and within-fish distribution largely depends on fish host species and their respective feeding behaviour. Thus, fish that prey on other fish such as hake and cod, are usually more heavily infected with anisakid larvae compared to strict plankton feeders such as anchovy. However, we only know little about the spatial distribution of anisakid larvae in various economically important fish species, i.e. whether or not the larvae occur in the fillets of the actual fish species. In order to further investigate these aspects we have chosen to cover those species in the survey which represent either typical pelagic shoaling fish or typical ground dwellers, from all four fishing areas. Thus, among the pelagic fish species to be examined are herring (Clupea harengus), Atlantic mackerel (Scomber scombrus), blue whiting (Micromesistius poutassou) and anchovy (Engraulis encrasicolus) while European hake (Merluccius merluccius), haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua) will represent typical ground dwelling species in the project. On a lesser scale, or whenever available, we also aim to investigate monkfish (Lophius sp.), sea bass (Dicentrarchus labrax) and various tuna species since these, too, are commercially utilised on an industrial scale and are of importance in a number of major European seafood markets including Spain, UK, Italy and France.
We know from many scientific reports that all of these fish species or stocks are infected with anisakid nematodes, thus underlining the potential health risk or product quality reduction related to these species. However, the lack of pan-European systematic monitoring and sampling programs for anisakids means that there is only little information on temporal and spatial trends in the population dynamics of these parasites in the economically most important fisheries in European waters. This gap of knowledge, however, is now about to be filled through our efforts in the Parasite project to compile the necessary epidemiological data sets.
Since a huge sampling effort is expected during the project development, are there any further uses foreseen for those samples beyond the project?
One of the main goals of this part of the work is to provide relevant epidemiological information for the end-users. This will be achieved through interlinking this and the PARASITE Biobank solution (WP 3). The latter is a web-based database platform which enables partners and other stakeholders to obtain data sets and parasite material with high standards for sample traceability and integrity. Moreover, the Biobank will ensure availability of high quality biological material, well sorted, processed and preserved to meet the demands of research, and to facilitate the future development of diagnostic systems that enable precise classification, forecasting methods and identification of potential therapeutic targets.
This approach by interlinking the epidemiological data and sample compilation with a biobank function may help food producers to maintain safety, consistency and avoid consumer complaints or costly litigation because of rapid alert notifications.