Transcript Medical Protozoa - Shandong University

Introduction to
Medical Protozoa
Department of parasitology
Shenyi He
General Concepts
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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.
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.
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.
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.
Classification
Phylum:
Sarcomastigophora
Apicomplexa
Ciliophora
Class
Genera:
Zoomastigophora
Trypanosoma,
Trichomonas
Leishmania,
Giardia,
Lobosea
Entamoeba, Naegleria, Acanthamoeba
Sporozoea
Plasmodium,Toxoplasma, Cryptosporidium,
Isospora
Kinetofragminophorea
Balantidium
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.
Nutrition
• All parasitic protozoa require preformed
organic substances that is, nutrition is
holozoic as in higher animals.
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.
Basic structure
• 1. Cell membrane
• 2. Cytoplasm
organelles: pseudopodium(-diaamoeba); flagellum(-lla-flagellate);
cilium(cilia-ciliate)
• 3. Nucleus: two kinds of nuclei:
vesicular;
compact
Characteristics of
Pathogenesis
• 1. proliferation
• 2. Diffusion (disperse )
• 3. Opportunistic parasitosis
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
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