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 c_burton@seafish.co.uk 01967 431573 07876 035771 (Mobile)
Thank you. Enjoy your fish!
Craig Burton (Mobile)