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Public health risks from fish and fish products

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Presentation on theme: "Public health risks from fish and fish products"— Presentation transcript:

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 Parasite Xenobiote
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: Can be fatal (0.1 - 10%)
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 ( %)

8 Ciguatera Can be treated Best tactic – Avoidance
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 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 What happens
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 Laboratory confirmation
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 Gempylid 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 Rare and localised
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 Ichthyohepatotoxic 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 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 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 Infection rare in UK
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 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 Craig Burton 01967 431573 07876 035771 (Mobile)
Thank you. Enjoy your fish! Craig Burton (Mobile)

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