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1、医学寄生虫学 MEDICAL PARASITOLOGY 热带传染病学教研室 热带医学与公共卫生学系 1 第一篇 总 论 All three of us have been connected one way or another with the world of PARASITES Parasites are not generally regarded as being loveable When we refer to some people as parasites we are not being complimentary we are not praising them We t
2、hink that a parasite is the sort of person who goes through a revolving door on somebody else s push It is so unfair Unfair to the real parasites the innumerable and influential parasites of the natural world Your Majesties Your Royal Highnesses Your Excellencies Ladies and Gentlemen it is time for
3、parasites to get a little more respect 2 第一篇 总 论 医学寄生虫学 Medical Parasitology study of parasites that infect human their morphology life cycle and their relationships to host as well as environment for the development 3 医学寄生虫分类 医学原虫 protozoa 医学蠕虫 helminths 医学节肢动物 arthropods 4 我国有人体寄生报告的寄生虫达229种 5 6 医
4、学蠕虫 7 医学节肢动物 8 与诊断有关的寄生虫形态特征 与致病和防治有关的生活史环节 重点掌握 9 几个概念 1 寄生现象 1 共生 Symbiosis any organism that spends a portion or all of its life intimately associated with another living organism of a different species symbiont and its relationship is designated as symbiosis benefit or damage to the symbionts 10
5、 几个概念 1 寄生现象 At least three categories of symbiosis mutualism commensalisms and parasitism 1 互利共生 mutualism The association is beneficial to both parties depending on each other physiologically Flagellated protozoans gut of termites Wood chip cellulose compounds enzyme 11 几个概念 1 寄生现象 2 片利共生 commensa
6、lism One of the associated organisms is benefited and the other is neither benefited nor harmed It denotes an association which is beneficial to one partner and at least not disadvantageous to the other 12 几个概念 3 寄生 Parasitism One of the associated organisms is benefited and the other is injured 寄生物
7、 benefited an organism which is dependent on the other organism for its survival 寄生虫 Parasite 动物源 animals 寄生物 宿主 Host injured 寄生关系的演化 自由生活演化为寄生生活 形态变化 生理功能变化 毒力进化 免疫逃避功能 基因变异 13 寄生虫类别 体内寄生虫 体外寄生虫 ectoparasites are attached to the outer surface of the host or are superficially embedded in the body su
8、rface endoparasite live within the body of the host at sites such as the alimentary tract liver lungs etc 14 寄生虫类别 1 专性寄生虫 Obligatory Parasite parasite that are entirely or partially at least dependent on their hosts physiologically dependent up their hosts and usually can not survive if kept isolat
9、ed from them 2 兼性寄生虫 facultative Parasite parasite that are capable of living either free on a host Facultative parasite are essentially free living organisms that are capable becoming parasitic if placed in host The organism does not of necessity have to be a parasite at any stage of its existence
10、15 寄生虫类别 3 偶然寄生虫 accidental parasite 有些寄生虫由于偶 然的机会进入或附着于非正常宿主 但不能在此非正常 宿主长期寄生的寄生虫 4 机会性致病寄生虫 opportunistic parasite 在宿 主体内通常处于隐性感染状态 但当宿主免疫功能底下 时 可出现异常增殖且致病力增强 如弓形虫 隐孢子 虫等 16 宿主类别 1 终宿主 definite host host in which sexual reproduction occurs or adult stage of the parasite develop 2 中间宿主 intermediate
11、host host in which larval stage of the parasite develop or asexual reproduction occur They are usually designated first and second intermediate hosts if there are more than one 17 3 保虫宿主 RESERVOIR HOST AN VERTEBRATE ANIMAL OTHER THAN A HUMAN THAT IS NORMALLY INFECTED WITH A PARASITE WHICH CAN ALSO I
12、NFECT HUMANS IS CALLED A RESERVOIR HOST EVEN IF THE ANIMAL IS A NORMAL HOST OF THE PARASITE IT IS A RESERVOIR FOR A ZOONOTIC INFECTION OF PEOPLE 保虫宿主 18 4 转续宿主 PARATENIC HOST WHEN A PARASITE ENTERS THE BODY OF A ABNORMAL HOST AND DOES NOT UNDERGO ANY DEVELOPMENT BUT CONTINUES TO STAY ALIVE AND BE IN
13、FECTIVE TO A NORMAL HOST 转续宿主 19 带虫者 Carrier A person who carries a certain parasite without displaying any signs or symptoms of disease 寄生虫病 parasitic disease 当寄生虫侵入宿主 宿主 不能控制寄生虫的生长 发育 繁殖 寄生虫对宿主产生 不同程度的损害 出现病理变化和临床症状 生物媒介 Biological vector 将病原体从一 个宿主传给另一宿主造成感染的生物体 20 幼虫移行症 larva migrans 在某些动物体内寄生 的
14、蠕虫幼虫进入非正常宿主内 发育受阻 不能发育为 成虫 但可在体内长期移行 破坏组织 产生相应的病 损 异位寄生 寄生虫在主要寄生部位 正常寄生部位 以 外的组织或器官内寄生 并造成损伤 出现较复杂的症 状和体征叫异位寄生 寄生虫感染特点 带虫者 慢性感染和隐性感染 多寄生现象 幼虫移行症 21 生活史 生活史 life cycle 寄生虫生长发育 繁殖和传 播的全过程 可分为直接型 和间接型 感染阶段 生活史中某个阶段在入侵人体后能继续 生长发育 感染途径 侵入人体的途径 移行途径 从入侵处到达特定部位定居所经过的途径 寄生部位 寄生虫特定的定居部位 22 寄生虫对宿主的致病作用 1 夺取营养
15、 23 24 寄生虫对宿主的致病作用 2 机械损害 tissue damage mechanical disruption of cells by the parasite 3 毒性作用 4 免疫病理损害 I IV型变态反应 25 2015 11 05 HIV感染哥伦比亚男子的淋巴结及肺组织结节的瘤体样本 其中细胞显示出单形性 未分化细胞 具有明显恶性肿瘤细胞的特征 但其大小显然不是人类的细胞 通过DNA序列分析和原位杂交证实为膜壳绦虫细胞及其基因组 膜壳绦虫寄生在肠 道 很少在肠外组织寄生 发现6个绦虫基因存在插入突变 这些基因的哺乳动物同源基因与癌症相关 这些 突变可能在免疫缺陷体内被选择
16、 并启动细胞增殖 绦虫具有干细胞 具有增殖能力 此病例的细胞与绦虫干细胞一致 因此推测在免 疫缺陷的宿主中 绦虫干细胞的插入性突变累积导致其恶变 寄生虫来源的肿瘤细胞引起人类疾病是新的发现和挑战 26 肠系膜静 脉 肝脏虫卵肉芽肿 肝纤维化 肝硬化 门脉高压 血吸虫病性肝纤维化机制及与肿瘤发生发展的相关性 肝癌 27 寄生虫感染的免疫特点 1 抗原复杂 1 抗原多而复杂 全基因组可编码6000个蛋白 是细菌 的20倍 n血吸虫全基因组可编码约20000个蛋 白 28 2 寄生虫抗原具有种 株和期的特异性 3 抗原变异性 寄生虫感染的免疫特点 疟原虫基因组富含变异基因家族 基因家族有Var Rif Stevs Clag等 变异基因家族是生物体适应外界环境变化的产物 Var基因的产物 PfEMP1 脑型疟疾的关键分子 29 疟疾 全球每年死亡300万 仅非洲每天死亡约6000人 PfEMP1 恶性疟红细胞膜蛋白1 Var基因家族 30 1 2 3 5 6 7 8 11 12 14 13 10 9 4 31 寄生虫感染的免疫特点 嗜酸性粒细胞增多 嗜酸性粒细胞增高是蠕虫感染的临床特征 蠕虫抗
