II. Definitions
- Protozoa
- Single cell, eucaryotic, motile, parasitic Microorganisms in the animal kingdom protista
- Some Protozoa have cilia or flagella to aid motility
III. Pathophysiology
- Single cell, eucaryotic, motile, parasitic Microorganisms
- Variable size (5 microns to 2 mm)
- Cytoplasmic membrane
- Cytoplasm layers
- Ectoplasm (outer)
- Endoplasm (inner)
- Organelles
- Nuclei (1-2)
- Mitochondria
- Endoplasmic reticulum
- Food vacuoles
- Cilia or flagella may be present (to aid motility)
- Nutrition
- Cytostome (mouth-like cell entry) allows ingestion of small particles
- Some organisms can ingest entire cells
- Reproduction
- Asexual reproduction with DNA duplication and cell division
- Sexual reproduction with fusion of 2 cells, DNA exchange, followed by cell division
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Cyst formation
- Protective coat secreted by Protozoa in response to harsh environments
- Intestinal Protozoa cause infection via ingested cysts
- After ingestion, cysts transform into motile form (trophozoite)
IV. Causes: Protozoal Infections in Humans
- Intestinal Protozoa
- Protozoal Infections in Immunocompromised Patients (e.g. AIDS)
- Toxoplasmosis
- Pneumocystis jiroveci (Pneumocystis carinii, also classified as a Fungus)
- Cryptosporidiosis (see Diarrhea above)
- Isospora belli (see Diarrhea above)
- Sexually Transmitted Protozoa
- Meningitis-Causing Protozoa (found in fresh water and moist soil)
- Vector-Borne Protozoa
- Malaria (Mosquito Borne Infection)
- Babesiosis (tick borne infection)
- Leishmaniasis (vector-borne by sandfly)
- African Sleeping Sickness (African Trypanosomiasis, vector-borne by Tsetse Fly)
- Chagas Disease (American Trypanosomiasis, vector-borne by Reduviid Bug)
V. References
- Gladwin, Trattler and Mahan (2014) Clinical Microbiology, Medmaster, Fl, p. 336-51
- Yaeger (1996) Protozoa, in Baron, Medical Microbiology, 4th ed, Galveston, Chap 77