Food borne animal parasites, viruses and food borne biohazards - PowerPoint Presentation

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Food borne animal parasites, viruses and food borne biohazards

Dept. of Food Science & Technology

Wayamba

University of Sri Lanka

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Food borne illnesses

Parasites

Viruses

Biohazards (toxins)

Bacteria

Chemicals

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Parasites

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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)

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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

CryptosporidiumCyclosporaEntamoeba

Giardia

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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 cystsby ingesting water, soil, vegetables, or anything contaminated with 

oocysts shed in the feces of an infected animalfrom a  blood transfusion or organ transplanttransplacental

transmission  from mother to fetus, particularly when T. gondii is contracted during pregnancy

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Toxoplasma

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Life cycle

Sexually reproduce  

only within the 

intestines of members

of the cat family (felids) 

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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 eggsUnpasteurized milk, particularly goat's milk

Contact with cat feces, including changing of cat litter trays

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Cryptosporidium

Mainly

Cryptosporidium

parvum

Cause  cryptosporidiosis, a parasitic disease  of the mammalian intestine tract

Primary symptoms - acute, watery, and non-bloody 

diarrhoeaOther symptoms -anorexia, nausea/ vomiting and abdominal painThe diagnosis of 

C. parvum consists of serological tests and microscopic evaluation of oocysts

in stools using  Kinyoun acid-fast staining

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Life cycle

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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 cryptosporidiosisPeople who drink untreated waterPeople, including swimmers, who swallow water from contaminated sources

People who handle infected cattlePeople who eat contaminated food; meat, fish, milk, fruits and vegetables

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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

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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

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Life cycle

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Entamoeba

Entamoeba

histolytica

 An anaerobic, cause

 

Amoebiasis

Transmission of the parasite occurs when a person ingests food/water that has been contaminated with infected fecesCysts 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

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Life cycle

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On occasion, Entamoeba

is capable of traveling to the liver

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Giardia

Giardia

lamblia

Single celled,  flagellated, microscopic parasite that can live in the intestines of animals and people

Cause giardiasisGiardiasis does not spread via the bloodstream, nor does it spread to other parts of the 

GI tract

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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

giardiasisFoodborne

giardiasis can result from the use of contaminated water for irrigating or washing fruits and vegetables

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Life cycle

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Symptoms of giardiasis

Most common symptoms- Diarrhea, abdominal cramps, gas, and nausea

Chronic infection might lead to dehydration and severe weight loss

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2. Parasitic Worms

animals that typically have a long cylindrical tube-like 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

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Anisakis and

Pseudoterranova

(

Sealworm,Codworm)

Anisakiasis was first recognized as a human disease about forty years ago.Found with fishchub mackerel and flying squid in Japan and pickled anchovies, raw sardines,cold

smoked salmon, raw or pickled herring are some vectors.

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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

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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

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Life cycle of Anisakis

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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

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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.

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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.

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Life cycle of Ascaris

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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 symptomsthese worms irritate the intestinal lining and interfere absorption of fats and protein.Ascaris causes more severe infections in the liver or lungs.

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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.

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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.

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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.

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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

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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.

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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 thesnails and encyst in water or on aquatic plants.

Consumption of contaminated water or of raw aquatic vegetables allows for completion of the life cycle

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How is it infected..???

Consumption of

contaminated water

raw aquatic vegetables

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Causes due to infection

Mild infection

Anemia,

headache, and gastric distressHeavier infections severe abdominal pain, malnutrition, edema

sometimes intestinal blockage.

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cestoda

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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.

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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

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Taenia

life cycles involve two mammalian hosts.

Adults in the human intestine may live for more than twenty years, producing several thousand eggs dailyThat 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

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How is it infected ??

Via dirty hands or

Fecally

contaminated vegetablesContaminated waterOr foods

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Symptoms of infection

Altered appetite

Abdominal pain

Diarrhea Constipation

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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

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Food borne Biohazards

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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

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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

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Toxin classification

Organism

Toxin

Bacteria

Botulinum

toxin, Staphylococcus toxin

Fungi

Afalatoxin

, Mycotoxin, Ochratoxin,

Patulin

Toxic algae

Okadaic

acidNatural toxins

Histamine,

Glycoalcoloids

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Toxin characteristics

Non replicative (Most are

proteinaceous

)

Non transmittable (human to human)

NonvolatileColorlessOdorless

TastelessMost are stable at standard conditions

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1. Botulism toxin

Agent:

Chlostridium

botulinumToxicity: 1ng/kg

500g is enough to kill the human raceDisturb the acetylecholine mechanism at neuromuscular junctions

SymptomsNausea, vomiting, diarrhea, headache, lethargy, double vision, respiratory stress, death

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Food sourcesImproperly canned foods (>pH 4.6)

Smoked salmon, trout

Fermented foods (

Saeurkraut

, pickled vegetables)Foods preserved in oil (Fish)

Saeurkraut

Canned foods

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2.Staphylococcus toxin

Agent:

Staphylococcus

aureus

Toxicity: 1μ

g cause illnessDisturbs the regulation of intestinal fluid regulation systemSymptoms:Sudden nausea, vomiting, excessive salivation, abdominal cramps, diarrhea, dehydration

Toxin is heat stable

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Food sources

Cooked ham, meat products, poultry

Home made sausages

Milk, cheese

Cream filled pastries

Cooked ham

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3. Afalatoxin

Agent:

Aspergillus

flarus

Afalatoxin B1, B2, G1, G2 (B1 is the most common)Toxicity: 0.5-10 mg/kgLiver

cancer, chronic hepatitis, jaundice, cirrhosis (Low levels long time)Cause acute toxicity, and potentially

death (High exposure)

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Food Sources

Peanuts and peanut butter

Tree nuts such as pecans

Corn

WheatOil seeds such as cottonseed

peanut butter

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4. Ochratoxin

Agent:

Aspergillus

ochraceus

Toxicity: No documented acute toxicity in humansTolerable weekly intake 120ng/kg (EFSA)Has

genotoxic and teratogenic effectsRelatively heat stable

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Food Sources

Soy beans

Coffee beans

Grapes

PeanutsCereals

Grapes

Coffee beans

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5. Patulin

Agent:

Aspergillus

clavatus

. Penicillium expansumToxicity:

No documented acute toxicityProvisional maximum tolerable daily intake 0.4μg/kgRelatively heat stable and not destroyed by pasteurization

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Food Sources

Apple and apple juice

Pears, grapes, bilberries may affect

Sweet cider

Apple and apple juice

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How to control

Good agricultural practices to avoid insect damages and mold infection

Good storage practices (Store below 10

0

C, control moisture, control RH)Separation of contaminated foods before processing

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How to control

Follow proper food handling and canning methods

Maintain good hygienic practices

Rules

and Regulations

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Food Born Viruses

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Characteristics

Small microorganism

Parasites that replicate/ propagate themselves within suitable living host cells

Do not reproduce in food

Spread usually result of poor hygieneRelatively stable and acid resistant outside host cells

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Major 3 types

Food born viruses

Hepatitis A

Norwalk Virus

Rotavirus

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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 diseaseA 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

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Hepatitis A cont.…

Virulence

Mechanisms:

Ingest virus through food/water/fomite

Possibly infects intestinal cells

Moves to liverDoes not kill liver cellsImmune response - T-cell

destruction of infected cellsVirus excreted in bile, then faces

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Hepatitis A cont.…

Symptoms:

2 - 6 weeks after being exposed to the hepatitis A virus

systemic infection characterized by gastrointestinal manifestations and liver injury.

Sudden feverVomitingJaundice

abdominal discomfort and bile in urine (Dark urine)Fatigue

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2.

Rotavirus

Infection

Incubation

: 1-3 daysInflammation of the stomach and intestines

Infection in humans occurIngestion of contaminated food or waterDirect contact with contaminated surfaces and then putting the hands in the mouth

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Virulence Mechanisms:

Infects cells that line the small intestine cells

Produces enterotoxin

Induces gastroenteritis

Severe

diarrhea and sometimes death through gastroenteritisSymptoms:FeverStomach cramps

vomiting, and diarrheaDehydration

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3.

Norwalk Virus

Infection

Incubation: 12 to 48 hours

infection of the stomach and intestines

Transitions: ready to eat foods, molluscs and uncookedeating food or drinking liquids that are contaminated with norovirus

,touching surfaces or objects contaminated with norovirus then putting your fingers in your mouth, ortouched infected workers or any other foods contaminated with vomit or feces from an infected person

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Symptoms :NauseaVomiting (more often children)

Diarrhea

(more often adults)

AnorexiaLow grade fever, aches, chills, malaiseRecovery: 12 to 60 hours usuallyShedding up to 1 week! (

feces, vomit)

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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 diseaseA 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

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Referenes

http://www.foodsafetywatch.org/category/factsheets/biotoxins

/

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Reference:

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