医学寄生虫学：阴道毛滴虫

1、TRICHOMONADS毛滴虫Flagellated protists2 species of medical important: T. vaginalis Donne: Trichomoniasis T. tenax 口腔（牙周炎） T. Hominis 盲肠、结肠Trichomonas vaginalis, showing essentials of morphologyDiscovered in1836 by Donne, named T. vaginalis Donne in 1837Five flagella, four anterior and fifth incorporate

2、d within the UM （undulating membrane）Nucleus is anteriorAxostyle(轴杆）: commences at the nucleus and bisects the parasite Granules: hydrogenosomes（氢化酶体）, important for metabolismAF, anterior flagella; AX, axostyle; CO, costa; HY, hydrogenosome; N, nucleus; PB, parabasal body; PG, parabasal body and Go

3、lgi apparatus; RF, recurrent flagellum. Trichomonas vaginalis Relies on host for synthesis of essential molecules(nucleotides, fatty acids, amino acids) Ancient eukaryote 古老 Facultative anaerobe 兼性厌氧 Lacks mitochondria (无氧代谢）Contains hydrogenosomes 氧化酶体(involved in carbohydrate metabolism and drug t

4、herapy)HYDROGENOSOME（氢化酶体）Structure 0.5-2 m double membrane organelle no genetic materialPresent in anaerobic/aerotolerant organisms Trichomonads rumen-dwelling ciliates纤毛虫 free-living ciliates rumen fungi 瘤胃真菌（牛）A: T. vaginalis parasite as seen in broth肉汤 culture. The axostyle, undulating membrane,

5、 and flagella are clearly visible. B: T. vaginalis on the surface of a vaginal epithelial cell prior to ameboid transformation. C: Ameboid morphology of T. vaginalis as seen in cell culture. Note that the side opposite the undulating membrane adheres to the vaginal epithelial cell. Bars, 5 m. Clin.

6、Microbiol. Rev. 11:300MORPHOLOGY光镜下观察LIFE CYCLETrichomonas vaginalis resides in the female lower genital tract male urethra and prostate replicates by binary fission .No cyst formDoes not survive well in the external environment.Transmitted among humans, its only known host, primarily by sexual inte

7、rcourse .Trichomonasissexually-transmitted diseases STD (rare instance of neonatal infections acquired at birth) Common cause of vaginitisSingle form - trophozoite (no cyst form) Found in urogenital tract (vagina & vesicles & prostate in males) Extracellular - adheres to epitheliaPATHOGENESIS Molecu

8、lar mechanisms of pathogenesis: Adhesion play an important role: probably involves complex interactions. Parasite cell surface play main role. Temp., pH and time are important Excretion of soluble factors: extracellular proteinases Hemolysis Contact independent mechanisms: a soluble toxin? A possibl

9、e double-stranded RNA virus?Host immunity： female hormone level (estrogen)CLINICAL MANIFESTATIONS T. vaginalis infects the squamous epithelium in the genital tract (感染鳞状上皮细胞）More persistent in females Acute: Diffuse vulvitis （弥漫性阴道炎） Yellow or green discharge （黄绿色分泌物） Hemorragic spots in the vaginal

10、 mucosa （粘膜点状出血） Chronic: Mild symptoms with pruritus （瘙痒） Vaginal discharge mixed with mucus25-50% women are asymptomaticDisease conditions that could be associated with T. vaginalis:Ectopic pregnancy （异位妊娠） Infertility （不孕） Adverse pregnancy outcomes - premature rupture of fetal membranes, low bir

11、th weight, preterm delivery, postpartum endometritis （异常生产） Cervical carcinoma （宫颈癌）T vaginalis infection increases the susceptibility to others viruses:herpes, human papillomavirus (HPV), HIV.Persons with trichomoniasis as are twice likely to develop HIV infection as the general： (1) Disruption of

12、the epithelial monolayer leads to increased passage of the HIV virus; (2) T vaginalis induces immune activation, specifically lymphocyte activation and replication and cytokine production, leading to increased viral replication in HIV-infected cells.EPIDEMIOLOGY Cosmopolitan distribution More than 2

13、00 M cases worldwide with 2-3 million symptomatic infections annually in the USA Humans are the only natural host control of T vaginalis may represent an important means of slowing HIV transmission, particularly among African Americans. Global incidence of 8 STDsDIAGNOSIS Clinical presentation: disc

14、harge, strawberry cervix (草莓样宫颈） Visualization of the motile parasites in vaginal secretions (60-70% sensitivity.) Culture of parasites in special media. Antigen detection test from Genzyme Corp. (78.5-98.6% sensitivity) Oligonucleotide probe test (80-90% sensitivity) PCR-based test under developmen

15、tOSOM Trichomonas Rapid TestA rapid test for the detection of Trichomonas VaginalisEasy - to - Run - Dipstick simple, one reagent.Accurate - 95% agreement against Composite Reference Standard (culture and wet mount). Unaffected by other common infections.Fast - Results in approximately10 minutes.Flexible - Requires minimal training and lab personnel.Objective - Provides easy-