FOOD SAFETY HAZARDS IN AQUACULTURE SEAFOOD HYGIENE Lecture by Gza Szita

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FOOD SAFETY HAZARDS IN AQUACULTURE SEAFOOD
HYGIENELecture by Géza Szita
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Chemical compsition of the water
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Salt concentration of the sea water 0.35
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Chloride (Cl) 55.04 wt Sodium (Na)
30.61 wtSulphate (SO4) 7.68
wt Magnesium (Mg) 3.69 wtCalcium
(Ca) 1.16 wt.Potassium (K) 1.10 wt.
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Freshwater
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Total water 'hardness' (including both Ca2 and
Mg2 ions)
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Permanent hardnessis hardness (mineral
content) that cannot be removed by
boiling.CaSO4, CaCl2MgSO4, MgCl2
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Temporary hardnessis hardness that can be
removed by boilingCaHCO3- ? CaCO3 H2O
CO2
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Toxic materials in the waterAmmonia NH3Hydroxil
-amine OH- NH2Nitrite NO2Nitrate NO3Hidrogen
e-sulphide H2SSulfite ions SO3
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1. TERMS, PRODUCTION Seafood alI fish and
shellfish (crustaceans, molluscs)finfish salt-
and fresh-water wild fishery I aquaculturegt
300 speciesshellfishmolluscs (salt-water)
mussels, snails, clams, oysters,
abalone scallops, cuttlefishcrustaceans
(salt/fresh-water) shrimp or prawns,
crayfish,lobsters, crabs etc.
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Molluscs include chitons, clams, mussels,
snails,nudibranchs (sea-slugs), tusk shells,
octopus and squid.
Characteristics of molluscs Unsegmented soft
body Most have internal or external shell Have
a mantle (fold in the body wall that lines the
shell) Muscular foot and/or tentacles
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Mollusks
The mollusks or molluscs are the large and
diverse phylum Mollusca, which includes a variety
of familiar creatures well-known for their
decorative shells or as seafood. These range from
tiny snails and clams to the octopus and squid
(which are considered the most intelligent
invertebrates). The giant squid is the largest
invertebrate, and, except for their larvae and
some recently captured juveniles, has never been
observed alive, although the Colossal Squid is
likely to be even larger.Mollusks are
triploblastic protostomes. The principal body
cavity is a blood-filled hemocoel, with an actual
coelom present but reduced to vestiges around the
hearts, gonads, and metanephridia (kidney-like
organs). The body is divided into a head, often
with eyes or tentacles, a muscular foot and a
visceral mass housing the organs. Covering the
body is a thick sheet called the mantle, which in
most forms secretes a calcareous shell. Mollusks
have a mantle, which is a shell-like outer cover,
and a muscular foot that is used for motion. Many
mollusks have their mantle produce a calcium
carbonate external shell and their gill extracts
oxygen from the water and disposes waste. All
species of the phylum Mollusca have a complete
digestive tract that starts from the mouth to the
anus. Many have a radula, mostly composed of
chitin, in the mouth, which allows then to scrape
food from the surface by sliding back and forth.
Mollusks also have a coelom, made from cell
masses, where all organs are suspended. Unlike
Coelomates, mollusks lack body segmentation. Devel
opment passes through one or two trocophore
stages, one of which (the veliger) is unique to
the group. These suggest a close relationship
between the mollusks and various other
protostomes, notably the Annelids.
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Mollusks
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Bivalves
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The bivalves are the second largest class of
molluscs. They differ from snails in having two
shells, usually mirror images of each other. Some
like oysters and mussels live attached to rocks
and other hard surfaces while others, like pipis,
burrow in sand. Leptonoidean bivalves (in
picture) are a group which usually live
commensally with other animals. Most have a large
foot and are active crawlers.
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Limatula strangei. Some bivalves, such as the
scallops are able to actively move when
endangered by vigorously flapping their shells
and squirting out jets of water. Limatula also
moves very vigorously when disturbed. The
tentacles around the mantle edge are sticky, very
mobile and parts can break off them when the
animal is disturbed, leaving a potential predator
with a sticky writhing worm-like object to deal
with as the Limatula escapes (25mm).
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Octopus
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Hapalochlaena fasciata. There are a number of
species of blue-ringed octopus in Australian
waters. They are all dangerous to handle, as the
poison they use to kill their prey (crabs,
snails) is highly venomous to humans. This
species is common in New South Wales. Usually a
dull mottled colour, it can become yellow with
bright blue markings when disturbed.
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Squid
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Tunafish
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Swordfish
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2. FOODBORNE DISEASES FROM SEAFOOD

• raw shellfish or undercooked, smoked, lightly
  salted fishery products
• shellfish sedentary animals filter their food
  from coastal
• and estuar waters often subject to pollution by
  sewage
• effluents and rain runoff from agricultural lands
• bacteria, chemical contaminants are
  concentrated in shellfish
• quality of shellfish . quality of estuarine
  water in which they have been harvested
• . finfish prevalance of hazards higher in
  coastal and inland aquaculture
• post-harvest handling, processing

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Paragonimiasisendemic in Asia, South America,
West Afticasnails (first) crustaceans (second)
humans, mammals parasite infects the lungs
(tuberculosis)B. Nematodiasesintemediate
hosts marine or ftesh-water fishdefinitive
hosts marine mammals, birds, pigsmode of
infection ingestion of fish infective
larvaeCapillariasis- gastroenteritis may be
fatal- migratory fish-eating birds natural
definitive hosts spread faeces contaminated
with parasite eggs in freshwater fish ponds along
migratory routes- treatment mebendazole 400
mg/day for 20-30 daysAnisaldasis
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C Cestodiasesin humans fishborne infections
not commonDiphyllobothriasis- D. latum mainly
in cold waters (Eastern Europe, USA) - humans and
fish-eating mammals definitive" hosts- fish
intennediate hosts (salmon)- treatment
praziquantel, niclosamide
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Bacteriadivided into two groupsnaturally
present in the aquatic environment (indigenous
bacteria)present as a result of contamination
with human or animai faecescontamination during
post-harvest handling and processingEnterobacter
iaceaeintroduced into aquaculture ponds by
animaI manure or human waste significant
numbers in products from waste- fed systems -
Salmonellamay be naturally present in some
tropical aquatic environmentaquatic birds spread
themfishborne human infeétions rarestrains
isolated from humans are different from those
found in products from aquaculture- E. coli
bovine manure as pond fertilizer
pathogenicstrains into the pond water0157H7
cattle waterborne infection
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Shigella occasionally, very little
riskCampylobacter little information on the
occurrence in aquaculture use of poultry
manure for fertilizing ponds potential
riskVibrio spp. Salt-tolerant organisms
occour naturally in marine environments in both
tropical and temperate regionsV. cholerae
also occours in fresh water frequently isolated
from sediments, plankton, molluscs, finfish,
crustaceanspositive correlation with admixture
of contaminated human waste12 species associated
with seefoodsome human pathogenic Vibrio spp.
may also be fish pathogens
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V. Parahaemolyticus particularly associated
with consumption of raw marine crustaceans and
fishAeromonaspart of the normal aquatic
floraA. hydrophila fishbome disease' risk
is low
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Clostridium botulinumanaerobic,
neurotoxin-producing organismsseven types type
E is naturally found in aquatic environments
often isolated from fishprevention of toxin
productionListeria monocytogenesfrequently
isolated from aquaculture products in temperate
regionsrisk raw or without heat treatment
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VirusesViruses causing disease in fish are not
pathogenic to humanstransmission of enteric
virus diseases through waste-water reusesystems
is far not so important as bacterial or
helminthic diseases
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Other biological hazards large number of
toxic compounds produced by aquatic organisms can
cause human diseases produced by aquatic
microorganisms algae, bacteria that serve as
food for the larvae of commercially important
crustaceans and finfish possible sources of
infection in farmed finfish and
crustaceans ingestion of toxic microorganisms
or toxic products in feed marine zootoxins
are among the most highly toxic substances known
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Toxin LD50 (micro g/kg) in mice (IP)
Ciguatoxin 0.5 Saxitoxin 3.0
Tetrodotoxin 8.0 Botulinum A 0.0001
TCDD 2.0
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A. Ciguatera poisoningproduced by
dinoflagellate algaesmall fish feed algae
eaten by larger predatory fishannually
10,000-50,000 cases (USA Florida, Hawaii)
mostly due to group er, red snapper, Sphyraena
barracudaciguatoxin accumulates in the liver,
intestines, reproductive organs and muscles of
the fishCats are particularly sensitive
indicatorPrevention difficult ciguatoxin fish
do not appear or taste spoiled
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B. Saxitoxin poisoning (paralytic shellfish
poisoning, PSP)Saxitoxin produced by toxic
dinoflagellates food base for millions of
marine organismstoxin accumulates in the tissues
of bivalve molluscs (mussels, clams, oysters,
etc.)ingestion of a single clam, if heavily
contaminated can kilI a personPrevention
coastal shellfish monitoring programs prohibit
harvest during periods when toxin levels are high
("bIoom")
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C Tetrodotoxin poisoning (Puffer fish
poisoning)Many species of puffer fish
tetrodotoxinMajor cause offatal food poisoning
in Japan (fugu)(Captain Cook nearly died of
tetrodotoxin poisoning in New Caledonia in
1774)Tetrodotoxin potent vasopressor and
neurotoxin concentrates in the liver, skin
flesh becomes contaminated while the fish is
cleanedDogs, cats and birds are also
susceptible
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D. HistamineDue to ingestion of spoiled fish -)
mostly Scombroidae (eg, tuna, machereI)develops
post-mortem due to improper handling and
inadequate refrigerationtissues of scromboid
fish contains high level of histidine -).
histamine (Vibrio, Klebsiella, etc.)Histamine
degraded orally - cadaverine and putrescine
(cocontaminants) inhibit histaminases in human
intestineLevels gt 50mg histamine / 100 g of
flesh hazardous
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4. CHEMICAL HAZARDS Through exposure to
compounds used in the aquaculture systems or by
pollution of waterways or sources of water
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A. AgrochemicalsFertilizers (urea, ammon ion,
salts, trace element mixes) usually no risk to
food safety when used according to good
agricultural practiceWater treatment compounds
(lime, oxidizing agents, flocculants)
non-hazardousPesticides (algicides, herbicides)
no major risk disinfectants widely used no
risk to consumer chemotherapeutica
(antimicrobials, parasiticides). drugs
approved. drug residues
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- Metals(Pb, Cd, Cu, Zn, Fe ) present as a
result of geochemical processes result of
pollution pH of the water pollutants
Mercury Chlorinated compounds (DDT, PCBs,
dioxins)
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5. CONTROL OF FOODBORNE DISEASE FROM
SEEFOODFish must be washed and chilled in
ice or in cold water immediatley after
catching all of the ship equipment use for fish
chilling must be c1eaned and disinfected after
each debarkation fish must be eviscerated as
quickly as possible chilling is also required
during transportation to port and
during distribution for further pocessing
thorough washing is very important removes up
to 95 of putrefactive microorganisms present on
the fish skin during transportation for long
distances, the water must be aired optimum
temperature 4-80 oC
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Shellfishenvironmental monitoring of water
qualityUS Public Health Service shellfish
growing areas are surveyedfor safety only
those waters not subject to sewage contamination
and havingcoliform counts lt 70 organisms/100 ml
are approved for harvestingshellfish
transferred from marginally polluted areas
tounpolluted waters and left min. 14-28 days
will purifythemselves (depuration)public
education about the risks associated with eating
raw shell fish
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pH of fish meat 6.8 - 7.0H2S (lead acetate)
at 50 oCfree ammoniatrimethil-aminehistamine
- below 100 ppm