寄生虫阿米巴.ppt

Medical Protozoa
(Protozoology)
Department of Pathogen Biology
Nanjing Medical University
General Properties of theults in multi-cells (sporoblast
sporozoite buds sporozoites)
Internal budding – Endopolyogony (compare to schizogony). A special case is endodyogony which results in 2 cells (Toxoplasma)
Asexual
Sexual
Conjugation – by conjugating and exchanging nuclear materials of 2
organisms and then separating into new individuals
(Balantidium coli), only nuclei unite.
Gametogony– The process of producing gamets. This is followed by sexually differentiated cells uniting, resulting in zygote (Plasmodia), both cytoplasm and nuclei unite.
Mode of reproduction
Alternation of generations:
parasites reproduce by alternatively going through asexual and sexual means, . in Plasmodium, including asexual mode (schizogony) in human liver cells and red blood cells and sexual mode (gametogony) in mosquitoes.
Life cycle patterns
Two-host form
Mammals mammals, . Toxoplasma
Mammals vector arthropods, . Plasmodium
One-host form
One stage form – Trophozoite, . Trichomonas vaginalis
Two-stage forms – Trophozoite & Cyst, . Amoeba
Characteristics of Protozoan Infections
*In-host proliferation – parasitism
*No larva and adult differentiation but stage differences (. trophozoite, cyst)
*May be intracellular lodgment (. Plasmodium in
hepatocytes or red blood cells; Leishmania in
macrophages)
*Opportunistic infection (the immune-compromised
host, . AIDS patients who are easily infected by some protozoa, . Pneumocystis, that are harmless to normal hosts, and develop severe symptoms, and may result in death.)
Important medical protozoa
Including four classes:
Zoomastigophorea: The class (the flagellates), has one or more whip-like flagella and in some case, an undulatin