Food borne animal parasites, viruses and food borne biohazards

Dept. of Food Science & Technology

Wayamba University of Sri Lanka108072108075108078108079

Content• Parasites– Protozoan Parasites– Parasitic Worms

• Food Born Viruses –Hepatitis A – Rotavirus– Norwalk Virus

• Food borne Biohazards– Botulism toxin– Afalatoxin– Ochratoxin

 

Food borne illnesses

Parasites

Viruses

Biohazards (toxins)

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– 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

•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

non-bloody 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

• 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

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 abdominal pain, fever, severe diarrhea, vomiting

• 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

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 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

Nematoda

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

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

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

Trematoda

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.

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

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

How is it infected ??

• Via dirty hands • Fecally contaminated vegetables• Contaminated water or foods

Symptoms of infection

• 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 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

Food born

viruses

Hepatitis A

Norwalk Virus

Rotavir

us

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

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 • 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

intestinesInfection 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 gastroenteritisSymptoms:– Fever– Stomach cramps– vomiting, and diarrhea– Dehydration

3. Norwalk Virus• Infection• Incubation: 12 to 48 hours • Infection of the stomach and intestinesTransitions: – 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 oral-anal contact

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

• 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• Improperly canned foods (>pH 4.6)• Smoked salmon, trout• Fermented foods (Saeurkraut, pickled

vegetables)• Foods preserved in oil (Fish)

Saeurkraut Canned foods

2. Afalatoxin

• 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

• Peanuts and peanut butter• Tree nuts such as pecans• Corn• Wheat• Oil seeds such as cottonseed

peanut butter

3. Ochratoxin

• 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

• Soy beans• Coffee beans• Grapes• Peanuts• Cereals

Grapes

Coffee beans

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

Referenes

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