Transcript Food borne animal parasites, viruses and food borne biohazards

Food borne animal parasites, viruses and
food borne biohazards
Dept. of Food Science & Technology
Wayamba University of Sri Lanka
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Biohazards
(toxins)
Parasites
Food borne illnesses
Viruses
Bacteria
Chemicals
Parasites
Parasites..??
• Organisms that obtain their food from other living
creatures
• Smaller than their food source and this
distinguishes them from predators which also eat
other living things
• Common food borne animal parasites - worms
and protozoa
• Worms include tapeworms (cestodes), flukes
(trematodes) and roundworms (nematodes)
1. Protozoan Parasites
• One-celled organisms but are larger and more
complex than bacteria
• Generally not susceptible to antibiotics that kill
bacteria but there are effective drugs to treat some
(not all) parasitic infections
• Most common types;
– Toxoplasma
– Cryptosporidium
– Cyclospora
– Entamoeba
– Giardia
Toxoplasma
• Toxoplasma gondii
• Obligate, intracellular, parasitic protozoan that
causes toxoplasmosis
• Infection in humans and other warm-blooded
animals can occur
– by consuming raw or undercooked meat containing T.
gondii tissue cysts
– by ingesting water, soil, vegetables, or anything
contaminated with oocysts shed in the feces of an
infected animal
– from a blood transfusion or organ transplant
– transplacental transmission from mother to fetus,
particularly when T. gondii is contracted
during pregnancy
Toxoplasma
Life cycle
•Sexually reproduce
only within the
intestines of members
of the cat family (felids)
Risk factors of toxoplasmosis and
preventive methods
• Diminished vision or blindness after birth of child,
more severe effects include hydrocephalus,
convulsions, and calcium deposits in the brain
• Responsible for the deaths of AIDS patients and
causes encephalitis in many immunosuppressed
• Pregnant women and immunocompromised patients
should avoid the following:
– Raw or undercooked meat or eggs
– Unpasteurized milk, particularly goat's milk
– Contact with cat feces, including changing of cat
litter trays
Cryptosporidium
• Mainly Cryptosporidium parvum
• Cause cryptosporidiosis, a parasitic disease of
the mammalian intestine tract
• Primary symptoms - acute, watery, and nonbloody diarrhoea
• Other symptoms -anorexia, nausea/ vomiting and
abdominal pain
• The diagnosis of C. parvum consists of serological
tests and microscopic evaluation of oocysts in
stools using Kinyoun acid-fast staining
Life cycle
• The following groups have an elevated risk of
being exposed to Cryptosporidium:
– People who swim regularly in pools with insufficient
sanitation
– Parents of infected children
– People who take care of other people with
cryptosporidiosis
– People who drink untreated water
– People, including swimmers, who swallow water from
contaminated sources
– People who handle infected cattle
– People who eat contaminated food; meat, fish, milk,
fruits and vegetables
Cyclospora
• Cyclospora cayetanensis
• Cause cyclosporiasis
• By consuming food or water contaminated with C.
cayetanensis oocysts (the infective stage of the
organism)
• By putting anything into mouth that has touched
the stool of a person or animal with cyclosporiasis
• Symptoms of cyclosporiasis; watery diarrhea
(sometimes explosive), loss of appetite, bloating,
stomach cramps, nausea, vomiting, muscle aches,
low-grade fever, and fatigue
• Symptoms are more severe in persons with
weakened immune systems
Life cycle
Entamoeba
• Entamoeba histolytica
• An anaerobic, cause Amoebiasis
• Transmission of the parasite occurs when a person
ingests food/water that has been contaminated
with infected feces
• Cysts of the parasite are the viable form outside
the host. They can survive weeks in water, soils
and on foods under moist conditions.
• An active Entamoeba infection will cause diarrhea
Life cycle
• On occasion, Entamoeba is capable of traveling to
the liver
Giardia
• Giardia lamblia
• Single celled, flagellated, microscopic parasite
that can live in the intestines of animals and
people
• Cause giardiasis
• Giardiasis does not spread via the bloodstream,
nor does it spread to other parts of the
GI tract
How do people get giardiasis?
• Frequently associated with drinking
contaminated water, but some people might get
infected by consuming uncooked meat also
contaminated with G. lamblia cysts (the
infective stage of the organism)
• By putting anything into mouth that has
touched contaminated surfaces or the stool of a
person or animal with giardiasis
• Foodborne giardiasis can result from the use of
contaminated water for irrigating or washing
fruits and vegetables
Life cycle
Symptoms of giardiasis
• Most common symptoms- Diarrhea, abdominal
cramps, gas, and nausea
• Chronic infection might lead to dehydration and
severe weight loss
2. Parasitic Worms
• animals that typically have a long cylindrical tubelike body and no legs
• Various types of worm occupy a small variety
of parasitic niches, living inside the bodies of
other animals.
• There are three types of worms found which act
as parasites.
– Nematoda
– Trmatoda
– Cestoda
Anisakis and Pseudoterranova
(Sealworm,Codworm)
• Anisakiasis was first recognized as a human
disease about forty years ago.
• Found with fish
• chub mackerel and flying squid in Japan and
pickled anchovies, raw sardines,cold smoked
salmon, raw or pickled herring are some
vectors.
• Other fish, including whiting, mackerel,
pollack, and flounder,may also contain these
parasites with anisakid larvae.
• varies by season and increases with fish size
Water temperatures and seal populations may
also affect the abundance of these parasites
The way of forming of Anisakis
• Adult worms in these marine mammals produce
eggs
• That pass out with the feces, hatch, and the
larvae are consumed by shrimp.
• When fish or squid eat the shrimp, the larvae are
released, bore through the stomach wall,
• and may remain in the abdominal cavity or
penetrate near by muscles.
• The life cycle is completed when infected fish or
squid are eaten by marine mammals
Life cycle of Anisakis
What’s happened when larvae are
ingested by human ???
• Humans are an accidental host and these
larvae cannot mature in the human gut.
Instead the worms burrow into the intestinal
or stomach wall and may wander to the liver,
lungs or other tissues, causing
• gastric disturbances and allergic reactions.
larvae found in herrings body cavity
Ascaris lumbricoides
• Ascaris lumbricoides is a common intestinal
roundworm parasite infecting an estimated
one-quarter of the world’s population.
• Lack of adequate hygiene could spread egg of
this nematode to people who ingest
contaminated foods and drink water.
Life cycle of ascaris
• Humans are the only known host for this roundworm.
• Eggs passed out with feces may be ingested by the
same or another person
• By drinks contaminated water, eats with dirty hands, or
eats uncooked vegetables that have been fertilized
with contaminated human wastes.
• Upon ingestion, the eggs hatch in the intestine
• The worms may migrate to the lungs or
• liver before returning to the intestine and maturing.
Life cycle of Ascaris
What are the main causes of Ascaris ??
• Infected babies become stunts growth and
contributes to diarrheal infections and early
childhood mortality.
• Infected adults do not exhibit symptoms
• these worms irritate the intestinal lining and
interfere absorption of fats and protein.
• Ascaris causes more severe infections in the
liver or lungs.
Clonorchis/Opisthorchis (Liver flukes)
• In eastern and southeastern Asia, several related
parasitic worms of the genera Clonorchis and
Opisthorchis lodge in the liver of infected humans
and other animals causing blockage and
hyperplasia of the bile passages.
The way of contamination occur
• Cats and several other animals are vectors
• Raw fish can spread this liver flukes
• Additionally this will be a issue to some other
countries like USA who are importing fresh
water fishes of Asian countries.
Life cycle
• Involve two intermediate hosts, snails and
fish.
• Humans and other fish-eating animals
complete the life cycle by
– eating raw, infected fish and digesting out the
cysts.
– Then the larvae migrate to the liver, mature, and
produce eggs.
What happened after infection ??
• Light infections cause mild symptoms like liver
dysfunction
• Heavier infections result in hepatitis and
digestive disorders.
• According to epidemiological reviews there is
significant association between
– chronic infection
– liver cancer,
– cholangiocarcinoma
Fasciolopsis buski (Fasciolopsiasis,
Intestinal fluke)
• F. buski is the largest trematode infecting
humans,
• Worms most commonly inhabit the intestines
of farm pigs and school age children in Asian
countries.
Life cycle of Fasciolopsis buski
• This parasite requires a single intermediate host.
• Eggs are deposited in feces, hatch in water, and
the larvae penetrate snails and undergo
development.
• After 4–6 weeks the parasites emerge from the
• snails and encyst in water or on aquatic plants.
• Consumption of contaminated water or of raw
aquatic vegetables allows for completion of the
life cycle
How is it infected..???
• Consumption of
– contaminated water
– raw aquatic vegetables
Causes due to infection
• Mild infection
– Anemia,
– headache, and gastric distress
• Heavier infections
– severe abdominal pain, malnutrition, edema
– sometimes intestinal blockage.
cestoda
Taenia spp.
• Most familiar worm found in intestine of
human when they re infected.
• there are number of species which used
several animals as human, dog, even beares as
there hosts.
• T. solium, in particular, may be present in as
many as 20% of hogs
• causes debilitating human disease that is
difficult and expensive to treat
• Taenia life cycles involve two mammalian hosts.
• Adults in the human intestine may live for more
than twenty years, producing several thousand
eggs daily
• That pass out with the feces.
• If these are consumed by an intermediate host,
they develop into larvae (cysticerci) which
migrate to the muscles.
• Consumption of raw or inadequately cooked,
infected beef or
How is it infected ??
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Via dirty hands or
Fecally contaminated vegetables
Contaminated water
Or foods
Symptoms of infection
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Altered appetite
Abdominal pain
Diarrhea
Constipation
Problems related with infection
• Cysticercosis
• The most serious consequences occur when
the larvae reach the brain, causing
neurocysticercosis
• often triggers
– headaches, seizures, and other neurological
symptoms
Food borne
Biohazards
Biotoxins
• Biotoxin is a poisonous substance that is a specific
product of the metabolic activities of a living
organism (Plant, animal, bacteria, fungus)
• Cause food intoxications
• Toxicity depends on dose
Food Intoxication
• Microbes grow in foods produce toxins
• Toxins are ingested with the food and cause health
problems
• Most heat treatments are effective to kill
microbes, but toxins remain
Toxin classification
Organism
Toxin
Bacteria
Botulinum toxin, Staphylococcus
toxin
Fungi
Afalatoxin, Mycotoxin,
Ochratoxin, Patulin
Toxic algae
Okadaic acid
Natural toxins
Histamine, Glycoalcoloids
Toxin characteristics
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Non replicative (Most are proteinaceous)
Non transmittable (human to human)
Nonvolatile
Colorless
Odorless
Tasteless
Most are stable at standard conditions
1. Botulism toxin
• Agent: Chlostridium botulinum
• Toxicity: 1ng/kg
– 500g is enough to kill the human race
• Disturb the acetylecholine mechanism at
neuromuscular junctions
• Symptoms
– Nausea, vomiting, diarrhea, headache, lethargy,
double vision, respiratory stress, death
Food sources
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Improperly canned foods (>pH 4.6)
Smoked salmon, trout
Fermented foods (Saeurkraut, pickled vegetables)
Foods preserved in oil (Fish)
Saeurkraut
Canned foods
2.Staphylococcus toxin
• Agent: Staphylococcus aureus
• Toxicity: 1μg cause illness
• Disturbs the regulation of intestinal fluid
regulation system
• Symptoms:
– Sudden nausea, vomiting, excessive salivation,
abdominal cramps, diarrhea, dehydration
• Toxin is heat stable
Food sources
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Cooked ham, meat products, poultry
Home made sausages
Milk, cheese
Cream filled pastries
Cooked ham
3. Afalatoxin
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Agent: Aspergillus flarus
Afalatoxin B1, B2, G1, G2 (B1 is the most common)
Toxicity: 0.5-10 mg/kg
Liver cancer, chronic hepatitis, jaundice, cirrhosis
(Low levels long time)
• Cause acute toxicity, and potentially death (High
exposure)
Food Sources
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Peanuts and peanut butter
Tree nuts such as pecans
Corn
Wheat
Oil seeds such as cottonseed
peanut butter
4. Ochratoxin
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Agent: Aspergillus ochraceus
Toxicity: No documented acute toxicity in humans
Tolerable weekly intake 120ng/kg (EFSA)
Has genotoxic and teratogenic effects
Relatively heat stable
Food Sources
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Soy beans
Coffee beans
Grapes
Peanuts
Cereals
Coffee beans
Grapes
5. Patulin
• Agent: Aspergillus clavatus. Penicillium expansum
• Toxicity: No documented acute toxicity
• Provisional maximum tolerable daily intake
0.4μg/kg
• Relatively heat stable and not destroyed by
pasteurization
Food Sources
• Apple and apple juice
• Pears, grapes, bilberries may affect
• Sweet cider
Apple and apple juice
How to control
• Good agricultural practices to avoid insect
damages and mold infection
• Good storage practices (Store below 100C, control
moisture, control RH)
• Separation of contaminated foods before
processing
How to control
• Follow proper food handling and canning
methods
• Maintain good hygienic practices
• Rules and Regulations
Food Born
Viruses
Characteristics
– Small microorganism
– Parasites that replicate/ propagate themselves
within suitable living host cells
– Do not reproduce in food
– Spread usually result of poor hygiene
– Relatively stable and acid resistant outside host
cells
Major 3 types
Hepatitis
A
Rotavirus
Food born
viruses
Norwalk
Virus
1. Hepatitis A virus
• Infection
• Incubation: 10-50 days
• Deceases called as Hepatitis A
Infection in humans occur
– Eat or drink food or water that has been contaminated by
feces containing the hepatitis A virus (fruits, vegetables,
shellfish, ice, and water)
– Contact with the feces or blood of a person who currently
has the disease
– A person with hepatitis A does not wash his or her hands
properly after going to the bathroom and touches other
objects or food
– Participate in sexual practices that involve oral-anal contact
Hepatitis A cont.…
• Virulence Mechanisms:
– Ingest virus through food/water/fomite
– Possibly infects intestinal cells
– Moves to liver
– Does not kill liver cells
– Immune response - T-cell destruction of infected
cells
– Virus excreted in bile, then faces
Hepatitis A cont.…
• Symptoms: 2 - 6 weeks after being exposed to
the hepatitis A virus
– systemic infection characterized by
gastrointestinal manifestations and liver injury.
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Sudden fever
Vomiting
Jaundice
abdominal discomfort and bile in urine (Dark urine)
Fatigue
2. Rotavirus
• Infection
• Incubation: 1-3 days
• Inflammation of the stomach and intestines
Infection in humans occur
– Ingestion of contaminated food or water
– Direct contact with contaminated surfaces and
then putting the hands in the mouth
Virulence Mechanisms:
• Infects cells that line the small intestine cells
• Produces enterotoxin
• Induces gastroenteritis
• Severe diarrhea and sometimes death through
gastroenteritis
Symptoms:
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Fever
Stomach cramps
vomiting, and diarrhea
Dehydration
3. Norwalk Virus
• Infection
• Incubation: 12 to 48 hours
• infection of the stomach and intestines
Transitions:
– ready to eat foods, molluscs and uncooked
– eating food or drinking liquids that are contaminated
with norovirus,
– touching surfaces or objects contaminated with
norovirus then putting your fingers in your mouth, or
– touched infected workers or any other foods
contaminated with vomit or feces from an infected
person
•
• Symptoms :
– Nausea
– Vomiting (more often children)
– Diarrhea (more often adults)
– Anorexia
– Low grade fever, aches, chills, malaise
• Recovery: 12 to 60 hours usually
• Shedding up to 1 week! (feces, vomit)
Virulence Mechanisms:
– Eat or drink food or water that has been
contaminated by feces containing the hepatitis A
virus (fruits, vegetables, shellfish, ice, and water)
– Contact with the feces or blood of a person who
currently has the disease
– A person with hepatitis A does not wash his or her
hands properly after going to the bathroom and
touches other objects or food
– Participate in sexual practices that involve oralanal contact
Referenes
• http://www.foodsafetywatch.org/category/fac
tsheets/biotoxins/
Reference:
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