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Public health risks from fish and fish products. Scottish Food Enforcement Officers Perth April 08. Craig Burton. Potential hazards. Potential public health risks can arise from Toxins Parasites Xenobiotes (Man-made substances). Definitions. Toxin

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public health risks from fish and fish products

Public health risks from fish and fish products

Scottish Food Enforcement Officers

Perth

April 08

Craig Burton

potential hazards
Potential hazards
  • Potential public health risks can arise from
    • Toxins
    • Parasites
    • Xenobiotes (Man-made substances)
definitions
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
fish toxins
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
ciguatera
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
ciguatera1
Ciguatera
  • No external indication of toxicity
  • Heat stable
  • Possible 5 toxins involved
          • Ciguatoxin
          • Maitotoxin
          • Scaritoxin
          • Palytoxin
          • Okadic acid
  • Cause – dinoflagellates (Gambierdiscus toxicus)
ciguatera2
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%)
ciguatera3
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
tetrodotoxin
Tetrodotoxin
  • Most famous fish toxin
  • Japanese ‘Fugu’
  • Toxin found in
      • Puffer Fish
      • Ocean Sunfish
      • Porcupine Fish
  • Occurs in
      • Ovaries
      • Liver
      • Intestines
tetrodotoxin1
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)
tetrodotoxin2
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)
scombroid toxin
Scombroid toxin
  • Fish spoilage problem
  • Associated with
      • Tuna (all species)
      • Mackerels (all species)
        • Herring
        • Sardine
        • Anchovy
        • Bluefish
        • Amberjack
        • Kingfish
scombroid toxin1
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)
scombroid toxin2
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)

scombroid toxin3
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)
scombroid toxin4
Scombroid toxin
  • Often mistaken for fish allergy
  • Treat with anti-histamines (steroids)
  • Rarely fatal
  • Usually resolves 12 – 16 h, but can last days
rarer toxins
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
rarer toxins1
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
rarer toxins2
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
rarer toxins3
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
parasites
Parasites
  • Affect freshwater and marine fish
  • 76 recognised pathogenic species
  • 3 main groups:
      • Nematodes (Round worms)
      • Trematodes (Flukes)
      • Cestodes (Tape worms)
  • Also
      • Acanthocephala
parasites1
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
parasites2
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)
nematodes round worms
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
nematodes
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
nematodes1
Nematodes
  • Common fish hosts
      • Herring
      • Cod
      • Pollock
      • Haddock
      • Alaskan pollock
      • Mackerel
      • Anchovy
      • Tuna
      • Salmon
      • Squid
trematodes flukes
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)
trematodes
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
trematodes1
Trematodes
  • Symptoms
      • Intestinal flukes
          • Heterophyes spp
          • Metagonimus spp
        • Abdominal pain
        • Diarrhoea
          • Heart (muscle and valves)
          • Brain
trematodes2
Trematodes
  • Symptoms
      • Lung flukes
          • Paragonimus spp
        • Abdominal pain
        • Diarrhoea
        • Fever
        • Cough
        • Urticaria
        • Hepatospleanomegaly
        • Lung abnormality
        • Eosinophilia
          • Cough
          • Expectoration
          • Haemoptysis
          • Brain
          • Other organs
trematodes3
Trematodes
  • Symptoms
      • Other “fish flu”
          • Nanophyetus spp
        • Abdominal discomfort
        • Diarrhoea
        • Nausea
        • Fatigue
        • Weight loss
        • Eosinophilia
trematodes4
Trematodes
  • Common fish hosts
      • Mullet (Mugil spp)
      • Sea Bass (Dicentrarchus spp)
      • Herring
      • Salmonids
      • Tilapia
      • FW fish (carps)
cestodes tape worms
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)
cestodes
Cestodes
  • Symptoms
        • Can be none (asymptomatic)
        • Abdominal discomfort
        • Diarrhoea
        • Vomiting
        • Weight loss
        • Vitamin B12 deficiency
        • Pernicious anaemia
        • Intestinal obstruction
cestodes1
Cestodes
  • Common fish hosts
        • Pike
        • Perch
        • Burbot
        • Salmonids
        • Drums (Serranids)
        • Blue Whiting
        • Anchovy
        • Sardine
        • Turbot
prevention of parasite infection
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
xenobiotes
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)
xenobiotes1
Xenobiotes
  • From direct intervention
    • Veterinary medicine residues (aquaculture)
    • Polycyclic Aromatic Hydrocarbons (PAH) (processing)
    • Colourants (processing)
xenobiotes2
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)