Public health risks from fish and fish products

1. Public health risks from fish and fish products Scottish Food Enforcement Officers Perth April 08 Craig Burton

2. Potential hazards • Potential public health risks can arise from • Toxins • Parasites • Xenobiotes (Man-made substances)

3. Definitions • Toxin • A poisonous substance produced by an organism • Parasite • An organism that lives on or in another and derives nutrition from the host with a detrimental effect on the host. • Xenobiote • A substance that is not of biological origin found in the ecosystem or body

4. Fish toxins • 3 main toxins and several minor ones • Ciguatera • Tetrodotoxin • Scombroid poisoning • Clupeoid fish poisoning • Gempylid poisoning • Hallucinatory fish poisoning • Ichthyohaemotoxic poisoning • Ichthyohepatotoxic poisoning • Ichthyootoxic poisoning • Elasmobranch poisoning

5. Ciguatera • Most serious toxin world-wide and commonest • Mainly tropics and sub-tropics • Between 35o N and 35o S • Mainly reef fish species – 400 species implicated • Barracuda • Grouper • Snapper • Sea Bass • Coral Trout • Rock Cod • Jacks / Tevally • Parrot Fish • Moray Eel

6. Ciguatera • No external indication of toxicity • Heat stable • Possible 5 toxins involved • Ciguatoxin • Maitotoxin • Scaritoxin • Palytoxin • Okadic acid • Cause – dinoflagellates (Gambierdiscus toxicus)

7. Ciguatera • Symptoms: • Various, 2 – 12 hours after ingestion • Gastro-intestinal (nausea, vomiting, cramps, diarrhoea) • Cadiovascular (hypotension, tachycardia, bradycardia) • Neurological (headache, joint pain, delirium, paralysis, coma) • Sensation (itch, burning, numbness, tingling, dysaesthesia) • Skin lesions • Can be fatal (0.1 - 10%)

8. Ciguatera • Can be treated • Treat symptoms and provide support • Best tactic – Avoidance • Be cautious of large reef fish – especially predators • Do not eat fish liver, gonads or intestines • Caution if evidence of algal blooms • Sale of some fish species banned in some areas / seasons

9. Tetrodotoxin • Most famous fish toxin • Japanese ‘Fugu’ • Toxin found in • Puffer Fish • Ocean Sunfish • Porcupine Fish • Occurs in • Ovaries • Liver • Intestines

10. Tetrodotoxin • Heat stable • Slightly water soluble • Neurotoxin • 65 mg lethal • Has medical uses as a pain killer • Symptoms: 5 – 40 minutes (to 3 hours) • General (weak, pale, dizzy, unco-ordinated, salivation, sweating) • Neurological (numbness, paraesthesia, muscle twitching, paralysis) • Gastro-intestinal (nausea, vomiting, diarrhoea, pain) • Cardiovascular (chest pain, irregular pulse, hypotension)

11. Tetrodotoxin • Treatment • Respiratory support and general care • Can improve rapidly • Full resolution • Can be fatal (up to 60% if untreated and can kill in 17 mins)

12. Scombroid toxin • Fish spoilage problem • Associated with • Tuna (all species) • Mackerels (all species) • Herring • Sardine • Anchovy • Bluefish • Amberjack • Kingfish

13. Scombroid toxin • Cause • Fish treated incorrectly after capture or during storage • Left in the sun • Kept at room temperature for hours • What happens • Bacteria (Proteus, Clostridium, Salmonella, Klebsicila, Escherichia) convert Histidine in the muscles to Suarine(histamine-like)

14. Scombroid toxin • External Indication • Fish taste sharp, bitter or peppery • Laboratory confirmation • Histamine > 100 µM (mg) per 100 g fish muscle (Codex Std < 20 mg 100g-1)

15. Scombroid toxin • Symptoms: 20 – 60 mins • General (dry mouth, thirst, burning throat, cannot swallow, headache, metallic taste, weakness, pain, fever) • Gastro-intestinal (nausea, vomiting, diarrhoea, cramps) • Cardiovascular (palpitations, tachycardia, hypotension, ST depression) • Skin (general redness, itching, urticaria) • Respiration (bronchospasm, distress, cyanosis)

16. Scombroid toxin • Often mistaken for fish allergy • Treat with anti-histamines (steroids) • Rarely fatal • Usually resolves 12 – 16 h, but can last days

17. Rarer toxins • Clupeoid fish poisoning • Anchovy • Herring • Sardine • Rapid onset (minutes) • Often fatal • Liver failure (if survive) • Possibly related to Ciguatera poisoning • Gempylid poisoning • Escolars and pelagic mackerels • Diarrhoea

18. Rarer toxins • Hallucinatory fish poisoning • Mullet • Goatfish • Drummers • Rockcod • Surgeon fish • Rare and localised • Heat stable • Rapid onset - < 2 h • Symptoms • Impaired consciousness • Hallucination • Bizarre dreams • Paranoia • Resolves < 24 h

19. Rarer toxins • Ichthyohaemotoxic poisoning • Drinking fish blood, especially freshwater eels • Heat labile, protein-bound • Symptoms • Gastro-intestinal (nausea, vomiting, pain) • Neurological (numbness, weakness, paralysis) • Can be fatal • Ichthyohepatotoxic poisoning • Eating fish livers (tuna, mackerel, bass, grouper, snapper, sandfish) • Like vitamin A overdose • Ichthyootoxic poisoning • Eating fish eggs / roe (eg Barbel roe, but can affect caviar by bacterial spoilage) • Rare • Symptoms • Gastro-intestinal (nausea, vomiting, diarrhoea) • Neurological (tinnitus, respiratory distress, coma) • General (dry mouth) • Resolves in days

20. Rarer toxins • Elasmobranch poisoning • Associated with eating sharks and rays • Often from liver and gonads (but also in muscle) • Heat stable • Water soluble • Symptoms • Gastro-intestinal (nausea, vomiting, diarrhoea, pain) • Neurological (numbness, tingling, weakness, visual, paralysis, delirium, coma) • Cardiovascular (tachycardia, thready pulse) • Skin (itchy, peel off) • General (headache, pain, prostration) • Can be fatal • Recovery 5 - 20 days

21. Parasites • Affect freshwater and marine fish • 76 recognised pathogenic species • 3 main groups: • Nematodes (Round worms) • Trematodes (Flukes) • Cestodes (Tape worms) • Also • Acanthocephala

22. Parasites • Problems mainly associated with raw or lightly processed fish • Typical ‘risk’ dishes • Raw fish (eg Sashimi, Sushi) • Cold-smoked fish • Lightly salted (cured) fish (eg Gravfisk) • Pickled fish (eg Roll-mop herring) • Marinated fish • Undercooked fish

23. Parasites • Penetrate human gut if ingested • Inflammation • Ulceration • Granuloma formation • Can migrate to other organs (serious) • Infection rare in UK (but 40 – 50 million people (5-7%) affected world-wide, mainly Asia) • Can be of short duration (days) or can be chronic (decades)

24. Nematodes (Round worms) • Main condition • Anisakiasis (eosinophilic phlegmonous enteritis, eosinophilic granuloma) • Main causal agents • Herring Worm (Anisakis simplex) • Cod Worm (Pseudoterranova decipiens) • Eustrongylides spp • Gnathostoma sprinigerum(FW - Thailand) • Angiostrongylus cantonensis (FW) • Worms mainly found in fish gut, but move to muscle tissue after death

25. Nematodes • Symptoms (within hours) • Abdominal pain • Nausea • Vomiting • May cough up larvae • After 1-2 weeks, mimics Crohn’s disease (IBS) • Other (more serious) if migration to other organs • Brain • Heart • Lungs

26. Nematodes • Common fish hosts • Herring • Cod • Pollock • Haddock • Alaskan pollock • Mackerel • Anchovy • Tuna • Salmon • Squid

27. Trematodes (Flukes) • Fish are intermediate host • Several genera can infect humans • Heterophyes spp • Microphallus spp • Nanophyetus spp • Opisthorchis spp • Chlonorchis spp • Metagonimus spp • Paragonimus spp (crustacea)

28. Trematodes • Symptoms • Depends on main site of infection of fluke • Liver flukes • Chlonorchis spp • Opisthorchis spp • Abdominal pain • Nausea • Diarrhoea / Constipation • Eosinophilia • Cholangitis • Cholelithiasis • Pancreatitis • Cholangiocarcinoma • Heptamegaly • Malnutrition

29. Trematodes • Symptoms • Intestinal flukes • Heterophyes spp • Metagonimus spp • Abdominal pain • Diarrhoea • Heart (muscle and valves) • Brain

30. Trematodes • Symptoms • Lung flukes • Paragonimus spp • Abdominal pain • Diarrhoea • Fever • Cough • Urticaria • Hepatospleanomegaly • Lung abnormality • Eosinophilia • Cough • Expectoration • Haemoptysis • Brain • Other organs

31. Trematodes • Symptoms • Other “fish flu” • Nanophyetus spp • Abdominal discomfort • Diarrhoea • Nausea • Fatigue • Weight loss • Eosinophilia

32. Trematodes • Common fish hosts • Mullet (Mugil spp) • Sea Bass (Dicentrarchus spp) • Herring • Salmonids • Tilapia • FW fish (carps)

33. Cestodes (Tape worms) • Fish are intermediate host • Main concern 2 genera • Diplogonoporus spp • Diphyllobothrium spp • Diphyllobothrium latum • Broad tapeworm • Human optimum host • Grows to 10 m • Long lived (decades)

34. Cestodes • Symptoms • Can be none (asymptomatic) • Abdominal discomfort • Diarrhoea • Vomiting • Weight loss • Vitamin B12 deficiency • Pernicious anaemia • Intestinal obstruction

35. Cestodes • Common fish hosts • Pike • Perch • Burbot • Salmonids • Drums (Serranids) • Blue Whiting • Anchovy • Sardine • Turbot

36. Prevention of parasite infection • Freeze fish • EU requirement (853/2004) • Freeze to -20oC for 24 h • Other advice (FDA) • Blast freeze to -35oC for 15 h • Freeze to -23oC for 168 h • Freeze or store at -20oC for minimum of 7 d • Cook fish to > 60oC throughout depth • Candling and removal (minimise risk) • Belly flap removal (minimise risk) • Gut at sea or as kill (and cure) can reduce risk

37. Xenobiotes • Several non-biological substances of health concern can occur in fish and fish products • From the environment • Hydrocarbons • Persistent Organic Pollutants (Dioxins, Polychlorinated biphenols [PCB], Organophosphates, Organochlorides) • Polycyclic Aromatic Hydrocarbons (PAH) • Heavy metals (Pb, Hg (CH3-Hg), Cd etc) • Radionucleotides • Synthetic hormones (freshwater)

38. Xenobiotes • From direct intervention • Veterinary medicine residues (aquaculture) • Polycyclic Aromatic Hydrocarbons (PAH) (processing) • Colourants (processing)

39. Xenobiotes • Some have permitted maximum levels set in legislation • International (Codex Alimetarius) • European (1881/2006, 2377/90, 94/36/EC) • UK (Contaminants in Food Regs 2007) • UK fisheries and aquaculture monitored • Imports should be certificated (EU approved residue monitoring plan in export country)

40. Thank you. Enjoy your fish! Craig Burtonc_burton@seafish.co.uk01967 43157307876 035771 (Mobile)