Foodborne Intestinal Parasites PDF

Foodborne Intestinal Parasites Dr. Elfadil Abass 1  Outlines Entamoeba histolytica Giardia intestinalis Taenia solium and Taenia saginata (Cestode) Ascaris lumbricoides (Nematodes, roundworm)....

Foodborne Intestinal Parasites Dr. Elfadil Abass 1  Outlines Entamoeba histolytica Giardia intestinalis Taenia solium and Taenia saginata (Cestode) Ascaris lumbricoides (Nematodes, roundworm). 2  Entamoeba histolytica Causes intestinal disease: 1. Intestinal amebiasis- intestinal infection 2. Amebic dysentery- invasion of intestinal mucosa 3. Extra-intestinal amebiasis- infection of organs other than the intestine. 3  Entamoeba histolytica Morphology Trophozoites – It exhibits rapid, unidirectional, achieved with the help of pseudopods – The single nucleus – It contains RBCs, bacteria, yeast, and other debris may also reside in the cytoplasm – E. histolytica is the only intestinal ameba to exhibit this characteristic (RBCs). 4  Entamoeba histolytica Morphology Cysts – Are spherical to round and smaller than the trophozoites Mature cysts contain 1-4 nuclei (quadrinucleated) RBCs, bacteria, yeast are not found in the cyst stage. 5  Entamoeba histolytica Life cycle note – Once the infective cyst is ingested, excystation occurs in small intestine – A single cyst produces motile trophozoites that settle in the large intestine, where they feed and replicate Trophozoites may migrate to other organs in the body, such as the liver, and may cause abscess formation (extra-intestinal amebiasis) Encystation occurs and cysts pass out into the environment in human feces and are resistant to a variety of physical conditions. 6 7  Entamoeba histolytica Epidemiology – Transmission routes include: 1) Ingestion of the cyst in food 2) Houseflies and cockroaches may also serve as transport vectors by depositing infective cysts on unprotected food 3) Improperly treated water supplies. 8  Entamoeba histolytica Clinical symptoms – Infected patient shows no clinical symptoms- Asymptomatic Carrier State – The range of symptoms varies: 1) Amebic colitis, an intestinal infection: In amebic colitis symptoms, including diarrhea, abdominal pain and cramping 2) Amebic dysentery: A condition characterized by blood and/or pus and mucus in the stool. 9  Entamoeba histolytica Clinical symptoms Symptomatic Extraintestinal Amebiasis – The formation of an abscess in the right lobe of liver: Upper right abdominal pain Fever, nausea Vomiting (may occur) – Impact nutrition: Intestinal damage and malabsorption Diarrhea and nutrient loss Impact appetite and food intake Anemia and micronutrient deficiencies. 10  The flagellates The Flagellates – Are categorized into groups: 1. Intestinal flagellates (Giardia intestinals) 2. Urogenital flagellates (Trichomonas vaginalis) 3. Hemoflagellates (Trypanosoma and Leishmania spp) MORPHOLOGY – Movement is done by flagella in their trophozoite form. 11  Giardia intestinalis Are intestinal flagellates- it colonizes and reproduces in the small intestine – Causes diarrheal illness known as giardiasis- also known as "travelers diarrhea" that occurs during travel to less- developed countries. 12  Giardia intestinalis Morphology Trophozoites – The motile stage – The trophozoite is bilateral symmetry (similar anatomical parts on opposite sides) Two nuclei Four pairs of (8) flagella Sucking disc- for attachment and nourishment point of entry. 13 14  Giardia intestinalis Cysts – Typical oval with thick cell wall Immature cyst, contains – Two nuclei Mature cysts (infective stage), contains – Four nuclei. 15 (B) Stained stool specimen showing cysts of G. intestinalis. 16  Giardia intestinalis Life Cycle – Infection occurs by the ingestion of cysts in contaminated water, food, or by the fecal-oral route (hands or fomites) In the small intestine, excystation releases trophozoites which can attach to the mucosa – Encystation occurs in the colon Trophozoites can be detected in diarrheal faces Cyst is the stage found most commonly in non-diarrheal (formed) feces. 17 Giardia intestinalis 18  Giardia intestinalis Impact on nutrition: – Malabsorption of nutrients (damages intestinal villi) – Interfere with absorption of CHO, fats, proteins, fat- soluble- vitamins (A, D, E), contributing to nutritional deficiencies – Lactose intolerance due to intestinal damage, impairing digestion of dairy products – Chronic diarrhea and nutrient loss – Weight loss, appetite loss – Delayed cognitive development and learning difficulties – Disruption of gut microbiota and immune function. 19