TRICHOMONAS Genus Trichomonas shows the following important characteristics: I.An anterior tuft of flagellae, II.Undulating membrane, III.An axostyle, IV. Only trophozoite stage. Trichomonas is the simplest of all the protozoan parasites because it has only trophozoite stage. Trichomonas infects the urogenital tract unlike other members of the order Trichomonadida which inhabit the intestinal tract.
HUMAN TRICHOMONADS Trichomonads occurring in humans belong to 3 species : Trichomonas. vaginalis, Trichomonas.tenax & Pentatrichomonas.hominis (Trichomonas.hominis ). These species are highly site specific and typically morphologically similar to each other. Trichomonas.tenax is non pathogenic & inhabits the oral cavity. It is found in the pyorrhoeic dental sockets and around the tartar of the teeth. Pentatrichomonas.hominis (Trichomonas.hominis ) is non-pathogenic & inhabits the Illeocaecal region.
INTRODUCTION Sexually transmitted infection,known as Trichomoniasis. Discovered in 1836 Donne first observed the flagellate in 1837. 7.4 million cases reported every year 180 million people infected worldwide Resides in genitourinary tract of males and females 50% asymptomatic carriers HABITAT: T.vaginalis trophozoite inhabits the vagina in female, the prostate & seminal vesicles in males and urethra in both sexes.
Trichomonas. vaginalis Facultative anaerobic parasite It produces energy by fermentation of sugars in a structure called Hydrogenosome---A modified mitochondria in which enzyme of oxidative phosphorylation is replaced by enzyme of anaerobic fermentation.
MORPHOLOGY Trichomonas vaginalis belongs to Phylum Metamonada Class: Parabasalia, Order: Trichomonadida Family: Trichomonadidae. Genus : Trichomonas. Trichomonas vaginalis is a flagellated protozoan Trophozoite is the only stage present in the life cycle Infective stage of the parasite. No cystic stage. It is 7-30 µm long by 5-10µm wide It can survive outside the body at temp as low as 15 0 C for up to 48 hours. Trophozoite is pear shaped & shows “TWITCHING
MORPHOLOGY CONTD There are 4 anterior free flagella, arising from shallow depression, called periflagellar canal in the anterior end of the body. Fifth flagellum curves back along the margin of the undulating membrane & is called Recurrent flagellum. It lies in the shallow groove in the free margin of the undulating membrane. Just beneath the undulating membrane, a rigid filamentous cord called COSTA is present. Costa is believed to support the undulating membrane. It has a median Axostyle which is a hyaline rod like structure that runs throughout the entire length & comes out through the posterior end. Cytoplasm contains a large number of siderophilic granules.
EPIDEMIOLOGY Prevalence :Most common cause of vaginitis world wide It is cosmopolitan in distribution, however prevalence is not uniform because of sanitary and hygiene habits 20-40% in Women 10% in Men. Infected women harboring T.vaginalis in the genital tract---is the chief reservoir. Infected man is the carrier. Main source is vaginal discharge containing T.vaginalis. T.vaginalis infection is seen in all age groups. T.vaginalis infection is seen in both men &women.
EPIDEMIOLOGY High incidence of symptomatic infection occurs in women because of following reasons:1.Natural flora (bacteria) keep the pH of the vagina at 4-4.5 and ordinarily this discourages infections .T. vaginalis can survive at a low pH .Once established it causes a shift towards alkalinity (pH 5-6) which further encourages its growth.2.Presence of zinc & inhibitory substances in the prostatic secretions is harmful to T.vaginalis.Trichomoniasis has been implicated as a cofactor in the transmission of HIV.
TRANSMISSION Sexual intercourse Mutual masturbation Sharing sex toys Mother to child during vaginal delivery
LIFE CYCLE Life cycle of T.vaginalis is simple & it is completed in a single host either male/ Female. In the females, parasite gets the nourishment from 1. vaginal mucosa,2. ingested bacteria 3. RBC. It reproduces by longitudinal binary fission. Division of nucleus Division of neuromuscular apparatus Separation of cytoplasm into 2 daughter trophozoites. Trophozoites are the infective stages On sexual contact, trophozoites are transmitted to male & gets localized in urethra and prostate gland Replicates in the same way.
CAUSES OF VAGINITIS Three main types of vaginitis Bacterial vaginosis About 50% of vaginitis cases - Gardnerella or a mixed anaerobes Trichomoniasis About 20% vaginitis cases- Trichomonas vaginalis Candidiasis About 25% of vaginitis cases C. albicans (80-92%)
PATHOGENESIS & PATHOLOGY It is not an invasive parasite. It remains adherent to the squamous epithelium but not columnar epithelium. VIRULENCE FACTORS: Protein liquids & proteases –help in adherence. Lactic acid and Acetic acid- which lowers the vaginal ph low ph is cytotoxic to vaginal epithelial cells. Enzyme Cysteine proteases CP39-- Responsible for hemolytic activity of the parasite. PATHOLOGY: Intracellular edema and “ chicken like epithelium” is the most characteristic feature.
Biological Mechanism Adhesion proteins on surface of flagella Ligand/Receptor Cytoadherence -11- 23 different CP’s (cysteine proteinases) CP’s play an important role in the pathogenicity of the parasite.
Characteristics of CP39 The characteristics of CP39 are: It is present in vaginal secretions in patients with trichomoniasis Its optimal temperature is 37˚C and a pH range of 3.6 to 7.0 Suggested to be involved in tissue damage. Has broad substrate specificity Plays a role in parasite survival and immune evasion by degrading hemoglobin and immunoglobulins. Indicative that CP39 plays a role in trichomonal infection
SIGNS & SYMPTOMSIn females there is… In males there is… urethritis, vaginitis&cervicitis. whitish discharge inflammation of the vaginal although rare canal pain and burning vulvar itching leading to during urination . edema tenderness and chaffing redness yellow and green, foul smelling discharge painful urination-dysuria pain during sex -dyspareunia punctuate hemorrhages on the cervix known as colpitis macularis or strawberry
COMPLICATIONS In women-PID is the most common & important complication. Pregnant women infected with T.vaginalis infection --- likely to have 1.PROM 2. Premature birth 3. Pre-term/ Low birth weight baby. In men, common complications are prostatitis, Epididymitis, Urethral stricture & Infertility.
LABORATORY DIAGNOSIS I.Direct Detection. II. Culture. III. Antigen detection IV. Nucleic acid detection Techniques.
SPECIMENS In women : Vaginal discharge, Endocervical specimens. Endocervical specimens are not used for wet mount preparations, because of small number of parasites— can collected for culture. In men : 1.urethral discharge 2. prostatic fluid 3.Early morning first voided urine sediment. 4. Urethral swab before voiding urine 5. Semen. Cultures of urethral scrapings/ urine are the most effective method for diagnosis of the condition.
DIRECT DETECTION MICROSCOPY—Saline Wet mount Fixed smears are stained by 1.Acridine orange staining. 2.Papinicolaou staining. 3.Giemsa staining. 4.Leishman staining. 5.Direct Fluorescent Antibody staining.
WET MOUNT Specimen is collected by a swab from lateral &anterior fornices of the vagina. It is mixed with a drop of saline & a cover slip is placed over it. Microscopy shows : T.vaginalis shows jerky & twitching motility. PMN’S and Bacterial flora. Sensitivity of wet mount prep with vaginal secretion is 50-70%. Amies gel agar transport medium can maintain the viability for culture of T.vaginalis.
PERMANENT STAINING 1.Acridine orange staining—Rapid & accurate method. 2.Papinicolaou staining: Sensitivity is same as wet mount 3.Giemsa staining. 4.Leishman staining. 5.Direct Fluorescent Antibody staining: It is more sensitive than wet mount. Rapid method. Disadvantage is the requirement of fluorescent microscope.
CULTURE Culture is the gold standard. It is the most sensitive method (>80%). Specimens are inoculated immediately into appropriate medium such as 1. Modified Diamond’s medium, 2. Trichosel/ Hollander’s medium, 3. Trussel & Johnson medium 4.Trypticase serum medium. Cultures after inoculation are incubated aerobically. In a positive culture, actively motile trophozoites are demonstrated after 48 hrs of incubation at 37C. New Culture systems (In pouch TV) and systems of Empyrean diagnostics is commercially available which allows direct inoculation,Transport, Culture & Microscopy.
ANTIGEN DETECTION 1.ELISA—using Mab specific for a 65 KDa surface polypeptide of T.vaginalis. RAPID TESTS: Latex Agglutination test Immunofluorescent assay Two immunochromatographic capillary flow assays are commercially available-- 1.Osom Trichomonas Rapid test 2.Xenostrip Tv Trichomonas vaginalis test Serologic testing is NOT useful for diagnosis of Trichomoniasis.
MOLECULAR DIAGNOSIS A.DNA PROBES: These use synthetic oligonucleotide probes for detection of Trichomonas vaginalis DNA in vaginal secretions. Affirm VPIII—is a direct DNA probe test & tests for the 3 most common syndromes associated with increased vaginal discharge are: Bacterial vaginosis (Gardenerella vaginalis) Candidiasis (Candida.albicans) Trichomoniasis (T.vaginalis). Sensitivity of Affirm VPIII—is 90% and specificity is 98%. B. Nucleic acid based amplification methods: PCR & Transcription mediated amplification (TMA). These amplification methods are not FDA cleared.
OTHER TESTS DETERMINATION OF VAGINAL PH: Vaginal ph is usually above 4.5 in Trichomoniasis/ Bacterial vaginosis But not in Candidiasis. Vaginal ph is measured by Nitrazine paper method. WHIFF TEST/ AMINE ODOR TEST: This test is positive in Trichomoniasis/ Bacterial vaginosis In this test, vaginal swab is collected from the patient and is mixed with 10% KOH for the presence of polyamines. In the presence of Trichomoniasis, a fishy odour is released due to production of amines.
TREATMENT . Treatment : Single dose of Metronidazole 2 gm once, or Metronidazole PO 500 mg TDS for 7 days For recurrent Trichomoniasis :Metronidazole x 7 days and Repeat, if still positive then give Metronidazole 2 gm BD x5d Tinidazole or Miconazole used if resistant Metronidazole is contraindicated in the first trimester Intravaginal Clotrimazole 100mg vaginal suppository QID x7d Reinfection can happen almost immediately Treat the male sexual partner Tinidazole is an alternate drug
PREVENTION 1.Personal hygiene 2. Barrier precautions 3.Avoidance of sexual contact with infected partners. 4.Detection & Treatment of cases either males/females. NO VACCINE IS AVAILABLE.