简称弓形虫，弓浆虫寄生于人和许多简称弓形虫，弓浆虫寄生于人和许多种动物的有核细胞，引起人畜共患的弓种动物的有核细胞，引起人畜共患的弓形虫病形虫病(toxoplasmosis )特别在宿主特别在宿主免疫功能低下时致病，属机会致病原虫免疫功能低下时致病，属机会致病原虫(opportunistic protozoa)刚地弓形虫刚地弓形虫（Toxoplasma gondii） 一、形态一、形态在发育过程中，有在发育过程中，有5种形态滋养体滋养体 在有核细胞内，假包囊内滋养体叫速殖子在有核细胞内，假包囊内滋养体叫速殖子tachyzoite 包囊包囊 cyst 大量虫体分泌物形成的囊状结构，包囊内滋养体大量虫体分泌物形成的囊状结构，包囊内滋养体 叫缓殖子叫缓殖子bradyzoite卵囊卵囊oocyst 内含内含2个孢子囊，每个孢子囊内含个孢子囊，每个孢子囊内含4个子孢子个子孢子裂殖体裂殖体配子体配子体 Toxoplasma gondii in the bronchoalveolar lavage (BAL) material from an HIV infected patient. Numerous trophozoites (tachyzoites) can be seen, which are typically crescent shaped with a prominent, centrally placed nucleus. Most of the tachyzoites are free, some are still associated with bronchopulmonary cells. microscopical features of tachizoites of Toxoplasma gondii and peritoneal macrophages of mouse in peritoneal exudate. (SEM) microscopical features of tachizoites of Toxoplasma gondii and peritoneal macrophages of mouse in peritoneal exudate. (SEM) T. gondii: transmision electron microscopic picture. Longitudinal section of an endozoid. T. gondii: cross-section through an endozoid in an advanced stage of endodiogeny. The daugther cells appear to be surrounded. In each of these news cells there are two round bodies that lengthen forming the first rhoptries. Toxoplasma gondii in tissue from a cat. toxoplasmic pseudocyst within an inflammatory tissue reaction. (H&E stain). the pseudocysts of T.gondii can be observed in tissue sections with monoclonal antibodies. in cell cultures T.gondii proliferates to form a pseudocyst of 8-20 parasites. (Trophozoites in a THP-1 cell, Giemsa stain). 二、生活史二、生活史肠上皮细胞裂体增殖裂殖体—裂殖子肠上皮细胞配子生殖♀♂配子—合子—卵囊有核细胞内内二芽/二分裂滋养体有核细胞外包囊卵囊卵囊——子孢子子孢子终末宿主：终末宿主：猫科动物猫科动物中间宿主：中间宿主：极广泛，包极广泛，包括人及猫括人及猫随猫粪排出免疫力滋养体滋养体—速殖子速殖子包囊包囊——缓殖子缓殖子 寄生部位：寄生部位：所有有核细胞所有有核细胞宿主：宿主：广泛广泛感染阶段：感染阶段：卵囊，滋养体（速殖子、假包囊），卵囊，滋养体（速殖子、假包囊）， 包囊包囊感染方式：感染方式：1）后天感染）后天感染a)误食被卵囊污染的食物。
误食被卵囊污染的食物b)生吃肉类、乳类生吃肉类、乳类c)通过器官移植、输血等医疗手段通过器官移植、输血等医疗手段2）先天感染）先天感染孕早期感染弓形虫，通过胎盘传给胎儿孕早期感染弓形虫，通过胎盘传给胎儿 三、致病三、致病 人对弓形虫普遍易感，免疫功能正常时常处人对弓形虫普遍易感，免疫功能正常时常处于隐性感染状态，当宿主免疫功能低下时异于隐性感染状态，当宿主免疫功能低下时异常增殖而致病常增殖而致病速殖子是主要致病阶段速殖子是主要致病阶段虫体侵入有核细胞大量增殖，组织细胞被破虫体侵入有核细胞大量增殖，组织细胞被破坏，炎症细胞侵润，导致组织的炎症、坏死坏，炎症细胞侵润，导致组织的炎症、坏死 虫株毒力虫株毒力RH 株株（强毒株）可使宿主迅速死亡（强毒株）可使宿主迅速死亡Beverley 株株（弱毒株）（弱毒株） 增殖缓慢，易形成包囊增殖缓慢，易形成包囊危害因素危害因素弓形虫毒素弓形虫毒素(toxotoxin) 一种抗原，一种抗原， 致死因子，可致死因子，可致小鼠惊厥、后肢麻痹，几分钟后死亡致小鼠惊厥、后肢麻痹，几分钟后死亡弓形虫素弓形虫素(Toxoplasmin) 对鸡胚胎有致畸作用。
对鸡胚胎有致畸作用弓形虫因子弓形虫因子(Toxofactor) 培养的上清液提取物，可培养的上清液提取物，可阻止母鼠受孕，或流产，或胚胎发育停滞阻止母鼠受孕，或流产，或胚胎发育停滞 临床分型：临床分型：1、先天性弓形虫病、先天性弓形虫病孕早期弓形虫通过胎盘传给胎儿孕早期弓形虫通过胎盘传给胎儿,可造成流可造成流产，早产，畸胎或死产产，早产，畸胎或死产2、获得性弓形虫病、获得性弓形虫病因侵犯部位和机体反应性不同临床表现因侵犯部位和机体反应性不同临床表现常见的是常见的是发热发热（中、长程热），（中、长程热），淋巴结肿淋巴结肿大大（颌下、颈后），（颌下、颈后），神经系统的炎症神经系统的炎症（脑（脑炎、脑膜炎），炎、脑膜炎），眼部炎症眼部炎症（视网膜脉络膜（视网膜脉络膜炎） 弓形虫脑病 眼弓形虫病 CT scan of a toxoplasmic encephalitis.The typical lesion is an ipodense focal area with ring contrast-enhancement and edema. 四四 、实验诊断、实验诊断1、病原学诊断、病原学诊断（（1）体液涂片染色法）体液涂片染色法（（2）动物接种和细胞培养法）动物接种和细胞培养法2、血清学诊断、血清学诊断（（1）） IHA、、IFA、、ELISA 查抗原或抗体查抗原或抗体（（2）） PCR及及DNA探针技术探针技术 可早期诊断可早期诊断 T. gondii: direct detection of T.gondii in clinical specimens 五、流行五、流行本病是人兽共患寄生虫病，人群抗体阳性率本病是人兽共患寄生虫病，人群抗体阳性率25-50%。
许多与人关系密切的动物感染率亦高，是重要传染源许多与人关系密切的动物感染率亦高，是重要传染源流行因素：流行因素：1、、传染源传染源 猫科动物、其他哺乳动物、感染者猫科动物、其他哺乳动物、感染者2、传播途径、传播途径 胎盘；食入、伤口接触、输血等胎盘；食入、伤口接触、输血等3、易感人群、易感人群 普通人，胎儿、肿瘤和普通人，胎儿、肿瘤和AIDS患者更易感患者更易感 广泛流行的原因广泛流行的原因1、多个生活史阶段均有感染性多个生活史阶段均有感染性2、中间宿主极广泛中间宿主极广泛3、可在终宿主间、中间宿主间、终宿主与、可在终宿主间、中间宿主间、终宿主与中间宿主间互相感染中间宿主间互相感染4、包囊可在中间宿主组织内长期存在包囊可在中间宿主组织内长期存在5、卵囊排放量大，抵抗力强卵囊排放量大，抵抗力强 六、防治六、防治 对本病重在预防对本病重在预防 1、急性期患者常用乙胺嘧啶、磺胺类和增效、急性期患者常用乙胺嘧啶、磺胺类和增效剂联合用药疗程中可配用免疫增强剂剂联合用药疗程中可配用免疫增强剂2、加强对家禽、家畜和可疑动物的监测加强对家禽、家畜和可疑动物的监测3、加强肉类检疫和食品卫生管理。
加强肉类检疫和食品卫生管理 4、定期对孕妇作弓形虫常规检查、定期对孕妇作弓形虫常规检查 其他机会致病原虫其他机会致病原虫•肺孢子虫肺孢子虫寄生肺泡上皮细胞，引起间质性肺炎寄生肺泡上皮细胞，引起间质性肺炎•隐孢子虫隐孢子虫寄生肠粘膜，引起腹泻寄生肠粘膜，引起腹泻•等孢球虫等孢球虫寄生小肠上皮细胞内，引起腹泻寄生小肠上皮细胞内，引起腹泻•圆孢子虫圆孢子虫寄生肠粘膜，引起腹泻寄生肠粘膜，引起腹泻 [Last Modified: 11/20/2000 16:53:26 ] [Pneumocystis jiroveci (syn. Pneumocystis carinii)]Pneumocystis jiroveci cysts.A: 3 cysts in bronchoalveolar material, Giemsa stain; the rounded cysts (size 4 to 7 µm) contain 6 to 8 intracystic bodies, whose nuclei are stained by Giemsa; the walls of the cysts are not stained; note the presence of several smaller, isolated trophozoites.B: cysts in lung tissue, silver stain; the walls of the cysts are stained black; the intracystic bodies are not visible with this stain; baby who died with pneumonia in California. AB [Last Modified: 11/20/2000 16:53:26 ] [Pneumocystis jiroveci (syn. Pneumocystis carinii)]Pneumocystis jiroveci cysts.A: 3 cysts in bronchoalveolar material, Giemsa stain; the rounded cysts (size 4 to 7 µm) contain 6 to 8 intracystic bodies, whose nuclei are stained by Giemsa; the walls of the cysts are not stained; note the presence of several smaller, isolated trophozoites.B: cysts in lung tissue, silver stain; the walls of the cysts are stained black; the intracystic bodies are not visible with this stain; baby who died with pneumonia in California. ABA: 3 cysts in bronchoalveolar material, Giemsa stain; the rounded cysts (size 4 to 7 µm) contain 6 to 8 intracystic bodies, whose nuclei are stained by Giemsa; the walls of the cysts are not stained; note the presence of several smaller, isolated trophozoites.B: cysts in lung tissue, silver stain; the walls of the cysts are stained black; the intracystic bodies are not visible with this stain; baby who died with pneumonia in California. Pneumocystis jiroveci trophozoites in bronchoalveolar lavage (BAL) material; Giemsa stain. The trophozoite are small (size: 1 to 5 µm), and only their nuclei, stained purple, are visible (arrows). AIDS patient seen in Atlanta, Georgia. Indirect immunofluorescence using monoclonal antibodies against Pneumocystis jiroveci. Specimen from a patient with AIDS, seen in Georgia. •Lane S: Molecular base pair standard (100-bp ladder). Black arrows show the size of standard bands. •Lane 1: Single step PCR amplification with the pAZ102-E/pAZ102-H primer pair1 - diagnostic band size: 346 bp. •Lane 2: Nested PCR amplification with the ITS nested PCR primers, 1724F/ITS2R (first round) and ITS1F/ITS2R1 (second round)2 - diagnostic band size: 550 bp. Molecular Diagnosis A: Agarose gel (2%) analysis of PCR-amplified products from DNA extracted from a broncho alveolar lavage (BAL) diagnostic specimen of a patient with pulmonary symptoms. Oocysts of Isospora belli can also be stained with acid-fast stain, and can be visualized by epifluorescence on wet mounts, as illustrated. Three coccidian parasites that most commonly infect humans, seen in acid-fast stained smears (A, C, and F), bright-field differential interference contrast (B, D, and G) and epifluorescence (E and H, C. parvum oocysts do not autofluoresce). A, B, C: Oocysts of Isospora belli. The oocysts are large (25 to 30 µm) and have a typical ellipsoidal shape. When excreted, they are immature and contain one sporoblast (A, B). The oocyst matures after excretion: the single sporoblast divides in two sporoblasts (C), which develop cyst walls, becoming sporocysts, which eventually contain four sporozoites each. Images contributed by Georgia Division of Public Health. Oocysts of Cryptosporidium parvum stained by the modified acid-fast method. Against a blue-green background, the oocysts stand out in a bright red stain. Sporozoites are visible inside the two oocysts to the right. Oocysts of Cryptosporidium parvum, in wet mount, seen with differential interference contrast (DIC) microscopy. The oocysts are rounded, 4.2 µm - 5.4 µm in diameter. Sporozoites are visible inside the oocysts, indicating that sporulation has occurred. (In comparison, oocysts of Cyclospora cayetanensis, another important coccidian parasite of humans, are twice larger and upon excretion are not sporulated, i.e., do not contain sporocysts.) 。