Parasitology: Intestinal & Urogenital Protozoa Flashcards
What are organisms of the intestinal and urogenital protozoa?
- Amebae: Entamoeba
- Flagellates: Giardia and Trichomonas
- Ciliates: Balantidium
- Sporozoa: Cryptosporidium
What is the basic trophocytic physiology and structure of Entamoeba histolytica?
- Found in faeces and crypts of the large intestine
- Motile in fresh stool
- 12-50 µm in size
- Round nucleus with a karyosome
- Evenly distributed chromatin granules around the nuclear membrane
- Ingested erythrocytes in cytoplasm
What is the basic cystic physiology and structure of Entamoeba histolytica?
- Found in formed stool
- 10-20 µm in size
- 1-4 nuclei with a centrally located karyosome
- Round chromatoidal bars may be in cytoplasm
Discuss the epidemiology of E. histolytica.
- Worldwide
- Highest tropical and sub-tropical areas
- Asymptomatic carriers and are reservoirs for the spread
- Trophozoites cannot survive in the external environment and also not in stomach
- Flies and cockroaches are vectors for spread of E. histolytica cysts
- Oral-anal sex practices
Describe the life cycle of E. histolytica.
- Infx: Ingestion of cysts from faecally contaminated water, food, or hand
- Cysts: formed stool and Trophs: Watery stool
- Trophozoites cannot survive outside
- Low pH of stomach stimulates excystation
- Trophozoites migrate and multiply
- Cysts are protected by walls
- Trophs remain confined to intestinal lumen of asymptomatic carriers
- Invade intestinal mucosa and bloodstream
What is the lab diagnosis of E. histolytica?
- Stool: Cysts
- Tissue: Trophozoites
- Multiple samples because microscopic exam of stool is extensive
- Liver MRI or serological testing
What is the basic trophocytic physiology and structure of G. duodenalis?
- 9-12 µm long and 5-15 µm wide
- Flagella for movement
- 2 nuclei
- Central located karyosome
- 2 parabasal bodies
- Suckers for attachment
What is the basic cystic physiology and structure of G. duodenalis?
- 8-12 µm long and 7-10 µm wide
- Mature cysts: 4 nuclei
- Immature cysts: 2 nuclei
- Central located cysts
- Parabasal bodies
Describe the life cycle of G. duodenalis.
- Cysts and trophozoites passed in feces
- Cysts: resistant and responsible for transmission
- Cysts: hardy and survive in cold water
- Infx: Ingestion of contaminated food, water, fecal-oral route (hand or fomites)
- Excystation
- Trophozoites: longitudinal binary fission and remain in lumen of proximal small bowel
- Mucosa: ventral sucking disk
- Encystation: Colon
What is the lab diagnosis of G. duodenalis?
- Onset of diarrhea and abdominal pain
- Examine stool for cysts or trophozoites
- Excretion in “showers”
- Negative again and giardiasis is suspected: duodenal aspiration
- Immunological tests for fecal antigen
What is the basic trophocytic physiology and structure of T. vaginalis?
- Urogenital protozoa
- 4 anterior flagella and a short undulating membrane on one side
- 7-23 µm long and 6-8 µm wide
- Nucleus wider located
- Axostyle along center of parasite
Discuss the epidemiology of T. vaginalis.
- Worldwide
- Sex
- Fomites (toilets, clothes)
- Infants: infected birth canal
Describe the life cycle of T. vaginalis.
- T. vaginalis resides in the FLGT and male urethra and prostate
- Replicates by binary fission
- No cysts, only trophozoites
- Transmitted among humans
What is the lab diagnosis of T. vaginalis?
- Examine vaginal/urethral discharge for trophozoites
- Stain: Giemsa, Papanicolaou stain or unstained
- Culture: Kupferberg’s STS and Diamond’s medium
- Monoclonal fluorescent Ab stain or nucleic acid probe
- Serology testing for epidemiological surveillance
What is the basic trophocytic physiology and structure of N. coli?
- Covered with cilia
- 50-200 µm long and 40-70 µm wide
- Cytostome: funnel like mouth
- Large and small nucleus
- Food vacuoles
- 2 pulsating vacuoles seen in fresh preps
