Metazoan endoparasites as biological indicators of Baltic cod biology

The Baltic cod is a substock of the Atlantic cod Gadus morhua, and it is divided into two subpopulations (the western and the eastern stock) living in the semi-enclosed Baltic Sea. This brackish water area is receiving high salinity water from the North Sea through the Danish straits (the Great Belt, Øresund, and Little Belt) and freshwater from precipitation and the drainage areas in surrounding countries whereby marked differences with regard to salinity conditions occur in various parts of the area. The biological and hydrographical conditions determine the parasite fauna found in the Baltic cod, and therefore several of the Baltic parasites are biological indicators. Recommended indicator parasites comprise trematodes (Cryptocotyle lingua, Diplostomum spathaceum, Lepidapedon elongatum, Hemiurus lühei, Brachyphallus crenatus), nematodes (Hysterothylacium aduncum, Contracaecum osculatum, Anisakis simplex, Pseudoterranova decipiens, Capillaria gracilis), and acanthocephalans (Echinorhynchus gadi, Corynosoma spp., Pomphorhynchus laevis)

Effects of anisakid nematodes Anisakis simplex (s.l.), Pseudoterranova decipiens (s.l.) and Contracaecum osculatum (s.l.) on fish and consumer Health.

AbstractThe anisakid nematodes Anisakis simplex (Rudolphi, 1809), Pseudoterranova decipiens (Krabbe, 1878) and Contracaecum osculatum (Rudolphi, 1802) occur as third-stage larvae in marine fish products and may infect consumers ingesting raw or under-cooked fish products. Clinical symptoms associated with the infection, termed anisakidosis, vary from irritation of the oesophagus and stomach, via nausea, vomiting and diarrhoea to severe epigastric and abdominal pain. Third-stage larvae of A. simplex are found in the body cavity, musculature and various organs, P. decipiens occur mainly in the fish musculature (fillet) and C. osculatum larvae reside predominantly in the liver, body cavity, mesenteries and pyloric caeca. Preventive measures, including mechanical removal of worms, heat treatment or freezing to kill worms, are needed in order to reduce the risk of human infections. The anisakid life cycle involves several hosts. A. simplex nematodes use cetaceans (whales) as final hosts whereas P. decipiens and C. osculatum have their adult stage in pinnipeds (seals). Eggs released by worms in these hosts pass with feces to seawater where free-living third-stage larvae hatch from the eggs. Various invertebrates – including euphausiids, copepods and amphipods – feed on these larvae, become infected and serve as intermediate hosts. A range of fish species may serve as transport hosts following ingestion of infected invertebrates and the final stage develops after two additional moults in the stomach of marine mammals which consumed infected fish. Control measures may be implemented to reduce infections of fish stocks and thereby risk of human infections

Nyt bæredygtigt middel kan måske fjerne parasit, som angriber regnbueørreder

Hudsnylteren Ichthyobodo (Costia) og dens betydning og kontrol i økologisk ørredopdræt. I Shelterfish projektet er der særligt fokus er på at bekæmpe infektioner med især hudsnylteren Ichthyobodo necator – også ofte benævnt Costia necatrix. Den ydre overflade på en fisk omfatter hud, finner og gæller, og alle dele kan tjene som fasthæftnings- og opholdssted for en lang række parasitter. Økologisk opdrættet regnbueørred angribes af flere typer af disse hudsnyltere, men den parasitiske flagellat Ichthyobodo necator er en af de værste. Der findes ikke vacciner mod denne infektion, hvorfor tilsætning af aktive stoffer til opdrætsvandet oftest benyttes. I Shelterfish-projektet undersøges et nyt bakterielt overflade aktivt stof mod hudsnylteren. Det bakterielle overfladestof har vist gode resultater mod fiskedræber og amøber i gæller hos regnbueørred