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Introduction to Medical Protozoa

Introduction to Medical Protozoa. Department of parasitology Shenyi He. General Concepts. Eukaryotic Organisms Generally unicellular Found in every conceivable damp habitat Approximately 60,000 living species Largest visible to the naked eye Smallest only seen with the EM

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Introduction to Medical Protozoa

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  1. Introduction to Medical Protozoa Department of parasitology Shenyi He

  2. General Concepts • Eukaryotic Organisms • Generally unicellular • Found in every conceivable damp habitat • Approximately 60,000 living species • Largest visible to the naked eye • Smallest only seen with the EM • have all necessary life activities.

  3. Protozoa are one-celled animals found worldwide in most habitats. Most species are free living, but all higher animals are infected with one or more species of protozoa. Infections range from asymptomatic to life threatening, depending on the species and strain of the parasite and the resistance of the host.

  4. Structure Protozoa are microscopic unicellular eukaryotes that have a relatively complex internal structure and carry out complex metabolic activities. Some protozoa have structures for propulsion or other types of movement.

  5. Classification On the basis of light and electron microscopic morphology, the protozoa are currently classified into seven phyla. Most species causing human disease are members of the phyla Sacromastigophora and Apicomplexa.

  6. Phylum: Class Genera: Sarcomastigophora Zoomastigophora Trypanosoma, Leishmania, Giardia, Trichomonas Lobosea Entamoeba, Naegleria, Acanthamoeba Apicomplexa Sporozoea Plasmodium,Toxoplasma, Cryptosporidium, Isospora Ciliophora Kinetofragminophorea Balantidium Classification

  7. Reproduction Binary fission, the most common form of reproduction, is asexual; multiple asexual division occurs in some forms. Both sexual and asexual reproduction occur in the Apicomplexa.

  8. Nutrition • All parasitic protozoa require preformed organic substances that is, nutrition is holozoic as in higher animals.

  9. Life Cycle Stages • The stages of parasitic protozoa that actively feed and multiply are frequently called trophozoites; in some protozoa, other terms are used for these stages. Cysts are stages with a protective membrane or thickened wall. Protozoan cysts that must survive outside the host usually have more resistant walls than cysts that form in tissues.

  10. Basic structure • 1. Cell membrane • 2. Cytoplasm organelles: pseudopodium(-dia- amoeba); flagellum(-lla-flagellate); cilium(cilia-ciliate) • 3. Nucleus: two kinds of nuclei: vesicular; compact

  11. Characteristics of Pathogenesis • 1. proliferation • 2. Diffusion (disperse ) • 3. Opportunistic parasitosis

  12. Ecological Niches in the Human Body: • 1. Skin: Leishmania • 2. Eye: Acanthamoeba • 3. Mouth: Amoebae and flagellates (usually non-pathogenic) • 4.Gut: Giardia, Entamoeba (and invasion to liver), Cryptosporidium, Isospora, Balantidium • 5. G.U. tract: Trichomonas

  13. Ecological Niches in the Human Body: • 6. Bloodstream: Plasmodium, Trypanosoma • 7. Spleen: Leishmania • 8. Liver: Leishmania, Entamoeba • 9. Muscle: Trypanosoma cruzi • 10. CNS: Trypanosoma, Naegleria, Toxoplasma, Plasmodium

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