浙江大学医学院：原虫 Protozoa

Protozoa (原虫)

Protozoa (原虫)

General Account One-cell animal- monocellular or unicellular organisms with full vital fur nctions Species total named species: 65,000 parasitic: around 10,000 Entamoeba histolytica Entamoeba histolytica oIO immature cyst

General Account • One-cell animal – monocellular or unicellular organisms with full vital functions • Species – total named species:65,000; parasitic: around 10,000

Classification of protozoa Amoebae Flagellates Sporozoa d Ciliates

Classification of protozoa Amoebae Flagellates Ciliates Sporozoa

Life cycle patterns One-host form 1. One stage form -Trophozoite 2. Two stage form Trophozoite cyst TWo-host form 1 Mammals mammals 2. Mammals<> insect vectors

Life cycle patterns One-host form 1. One stage form – Trophozoite 2. Two stage form – Trophozoite & Cyst Two-host form 1. Mammals mammals 2. Mammals insect vectors

Mode of Reproduction Asexual Reproduction Binary fission result in 2 daughter cells Schizogony multiple fission result in multiple cells Budding Exogenous budding- by external budding result in multi- cells Endodyogony by internal budding result in 2 cells Sexual Reproduction Conjugation - exchange of nuclear material of 2 Gametogony sexually differentiated cells unite--zygote

Mode of Reproduction • Asexual Reproduction ▪ Binary fission – result in 2 daughter cells ▪ Schizogony – multiple fission result in multiple cells ▪ Budding ▪ Exogenous budding - by external budding result in multi- cells ▪ Endodyogony - by internal budding result in 2 cells • Sexual Reproduction ▪ Conjugation – exchange of nuclear material of 2 ▪ Gametogony – sexually differentiated cells unite -- zygote

Pathogenesis ● Host resistance Opportunistic Accidental Innate immunity (protozoa) infections Acquired immunity ● Parasite Invasion Toxin Mechanically damage Immune impair ● Immune inhibition hypersentivity

Pathogenesis • Host Resistance – Innate immunity – Acquired immunity • Parasite Invasion – Toxin – Mechanically damage – Immune impair • Immune inhibition • hypersentivity Opportunistic & Accidental (protozoa) infections

Opportunistic parasites o Opportunistic infection An infection by a microorganism that normally does not cause disease but becomes pathogenic when the body 's immune system is impaired and unable to fight off infection

Opportunistic parasites • Opportunistic infection – An infection by a microorganism that normally does not cause disease but becomes pathogenic when the body's immune system is impaired and unable to fight off infection

Amoebic Infections D Entamoeba histolytica D Acanthamoeba D Naegleria

Entamoeba histolytica Acanthamoeba Naegleria Amoebic Infections

Epidemiology 4th leading cause of death from parasitic diseases worldwide organism of deaths/yr infected Entamoeba 75,000 n300 million Ascaris ~200,000 N480 million Schistosoma 750,000 200 million Plasmodium 2-3 million N500 million (Malaria) Amoebiasis is not restricted to the tropics and subtropics, it also occurs in temperate and even in arctic and antarctic zones

Epidemiology • 4th leading cause of death from parasitic diseases worldwide Organism # of deaths/yr # infected Entamoeba ~75,000 ~300 million Ascaris ~200,000 ~480 million Schistosoma ~750,000 ~200 million Plasmodium 2-3 million ~500 million (Malaria) • Amoebiasis is not restricted to the tropics and subtropics, it also occurs in temperate and even in arctic and antarctic zones

Contaminated water is a source of infection

Contaminated water is a source of infection