Marine food borne pathogens

1. MARINE
FOOD BORNE
PATHOGENS

2. Introduction
• Marine food-borne pathogens are
organisms or toxins in seafood that can
cause illness in humans. They can be
bacteria, parasites, or natural toxins from
algae.
• Seafood can become contaminated either
naturally, from organisms that live in the
sea, or from pollution like sewage.
• People usually get infected by eating raw
or undercooked seafood, but sometimes
just handling it or having an open wound in
contact with seawater can cause infection.
• Pathogens are classified as bacteria,
parasites, or toxins from algae.

3. Major groups of pathogens
• BACTERIAL PATHOGENS : Bacteria: Multiply in seafood and
cause illnesses ranging from mild diarrhea to severe sepsis.
• Vibrio bacteria are naturally found in seawater. Vibrio
species are rod-shaped, Gram-negative bacterium.
• vibrio parahaemolyticus is common in warm waters and is a
leading cause of seafood-associated gastroenteritis.
• It is a halophilic gram negative, motile, oxidase positive,
straight or curved rod- shaped, facultative anaerobic
bacteria that occur naturally in marine water.
Gastroenteritis, wound infections, and septicemia are
three major diseases caused by V. parahaemolyticus.
• vibrio vulnificus is more dangerous. It can cause life-
threatening infections, especially in people with liver
disease or weak immunity. It can infect through wounds or
the gut. Death can occur quickly in severe cases. Raw
oysters are a common source.

4. • V. vulnificus has been divided into
three subtypes on the basis of
their biochemical properties are
following:
• Biotype 1 in crustaceans and
humans.
• Biotype 2 in eels.
• Biotype 3 in tilapia . It causes
wound infection in humans
during dealing with fish, also
causes liver illnesses and
hemochromatosis which leads to

5. Listeria
monocytogenes
can grow even in
the fridge. It’s a
major concern in
ready-to-eat
seafood like
smoked fish. In
pregnant women,
it can cause
miscarriage.
Salmonella is
spread by
contamination
during handling or
preparation, often
from raw sushi or
cross-
contamination
with dirty utensils.
It causes fever,
diarrhea, and
vomiting.
Clostridium
botulinum
produces one of
the most potent
toxins known. It
thrives in oxygen-
free, improperly
preserved seafood.
The toxin can
cause paralysis
and breathing
problems.
It is spore forming,
anaerobic, Gram-
positive bacillus
bacteria. C.
botulinum produces
neurotoxin which
can contaminate
food.

6. Parasitic
Pathogens
Parasites: Often worms that infect fish
and then humans if the fish is
undercooked.
Anisakis simplex is a roundworm found
in raw or undercooked fish like
mackerel, herring, and squid. When
eaten, the larvae can attach to the
stomach or intestines, causing intense
pain, nausea, and sometimes allergic
reactions.
Diphyllobothrium latum, the fish
tapeworm, can grow very large in the
human intestine and absorb vitamin B12,
leading to anemia.Cooking or freezing fish
properly kills these parasites

7. Marine toxins
• Toxins: Chemicals produced by algae or during spoilage,
which remain dangerous even after cooking.
• Ciguatera toxin comes from algae that live on coral reefs.
Small fish eat the algae, bigger fish eat the small fish, and
humans get poisoned from eating those big fish, like
barracuda or grouper. It causes diarrhea, tingling, and
strange symptoms like reversed hot/cold sensation.
• Saxitoxin, linked to paralytic shellfish poisoning, comes
from algae blooms called “red tides.” Shellfish store the
toxin and pass it to humans. It can cause numbness and
even death from respiratory failure.
• Histamine or scombroid poisoning happens when fish like
tuna or mackerel spoil. Bacteria turn histidine into
histamine, causing rash, headache, and flushing.

8. Viruses
Norovirus It is known as “RNA calicivirus” highly transmissible
infection causing in humans.
A highly contagious virus; leading cause of seafood-related
gastroenteritis.
Source: Shellfish harvested from sewage-contaminated waters;
spread also via infected food handlers.
Symptoms: Nausea, vomiting, watery diarrhea, stomach cramps,
mild fever; starts suddenly and lasts 1–3 days.

9. Hepatitis A Virus
Virus that infects the liver.
Source: Raw or undercooked shellfish from contaminated waters;
also spread through poor hygiene in food preparation.
Symptoms: Fatigue, fever, nausea, abdominal discomfort, jaundice
(yellow skin/eyes).

10. Conclusion
• Marine food-borne pathogens are a global
food safety concern due to the popularity
of seafood and the high risk from raw or
lightly cooked products.Prevention relies
on clean harvesting waters, proper
storage, adequate cooking, and good
hygiene throughout the supply chain.

11. Reference
• Moat et al., Microbial Physiology
• Food borne pathogens in seafood : Eurasian
Journal of Agricultural Research 2021; Vol:5,
Issue:1, pp:44-58.
submitted by
shamsiya A A
M.Sc. microbiology 3rd
sem

12. Thank
you