机会致病寄生虫弓形虫微小隐孢子虫.pptVIP

* * * * * * * * * * * * * 输血可能感染哪些寄生虫病？ 为什么弓形虫的人群感染率很高，但实际发病并不高？ * * 人体寄生虫学 医学原虫学 医学节肢动物 线虫 吸虫 绦虫 叶足虫 鞭毛虫 纤毛虫 孢子虫 * * * * 圆形或卵圆形，10-12um，成熟卵囊内含有2个孢子囊，分别含有4个新月形的子孢子。 　　感染猫排卵囊1000万个/天，可持续10－20天；在常温常湿条件下可存活1－1.5年。 成熟卵囊 未成熟卵囊 活卵囊 * * * * 速殖子正侵入巨噬细胞 细胞中的滋养体 速殖子内二芽殖分裂 滋养体包括缓殖子和速殖子，呈新月形，利用顶端复合物入侵巨噬细胞，并在其内以二分裂方式增殖 * * 巨噬细胞破裂释放速殖子 * * * * * * * * * * * * * * * * * * * * 骨骼肌中的包囊H.E染色 脑组织中的包囊H.E染色 　　包囊直径可达5－100um，内含数千个滋养体(缓殖子)，可长期存在，当免疫力功能低下时释放缓殖子。猪肉中的包囊在冰冻条件下可存活55天。 * * 抗酸染色 抗酸染色 隐孢子虫卵囊 圆形或卵圆形，直径4-6um，囊内含有4个裸露的子孢子和残留体 * * 未染色 抗酸染色 侵入肠上皮细胞 * * * 由法国学者Nicolle及Manceaux在刚地梳趾鼠（Ctenodactylus gondii）的脾脏单核细胞内发现，虫体呈弓形，故命名为刚地弓形虫 * 虽然感染率很高，但是发病的并不多。为什么呢？ * Leslie Ash contracted toxoplasmosis in the second month of pregnancy Arthur Ashe developed neurological problems from toxoplasmosis (later found to be HIV-positive) Louis Wain was a prominent cat artist who later developed schizophrenia which some believe to be due to his constant exposure to cats and thus Toxoplasmosis Martina Navratilova retired from a competition in 1982 with mystery virus later found to be due to the illness * * * Members of the cat family (Felidae) are the only known definitive hosts for the sexual stages of T. gondii and thus are the main reservoirs of infection. Cats become infected with T. gondii by carnivorism. After tissue cysts or oocysts are ingested by the cat, viable organisms are released and invade epithelial cells of the small intestine where they undergo an asexual followed by a sexual cycle and then form oocysts, which are excreted. The unsporulated oocyst takes 1 to 5 days after excretion to sporulate (become infective). Although cats shed oocysts for only 1 to 2 weeks, large numbers may be shed. Oocysts can survive in the environment for several months and are remarkably resistant to disinfectants, freezing, and drying, but are killed by heating to 70°C for 10 minutes.Human infection may be acquired in several ways: A) ingestion of undercooked infected meat containing Toxoplasma cysts