Food borne animal parasites, viruses and food borne biohazards

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

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 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

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