Trichomonas Medical Parasitology PDF

TRICHOMONAS MEDICAL PARASITOLOGY MORPHOLOGY It is pear-shaped or ovoid and measures 10–30 μm in length and 5–10 μm in breadth with a short undulating membrane reaching up to the middle of the body It has four anterior flagella and fifth running along the outer margin of the undulating membrane...

TRICHOMONAS MEDICAL PARASITOLOGY MORPHOLOGY It is pear-shaped or ovoid and measures 10–30 μm in length and 5–10 μm in breadth with a short undulating membrane reaching up to the middle of the body It has four anterior flagella and fifth running along the outer margin of the undulating membrane A prominent axostyle runs throughout the length of the body and projects posteriorly like a tail. The cytoplasm shows prominent granules It is motile with a rapid jerky or twitching type movement. HABITAT In females, it lives in vagina and cervix and may also be found in Bartholin’s glands, urethra, and urinary bladder. In males, it occurs mainly in the anterior urethra, but may also be found in the prostate. MODE OF TRANSMISSION Sexual transmission is the usual mode of infection. Trichomoniasis often coexists with other sexually transmitted diseases; like candidiasis, gonorrhea, syphillis, or human immunodeficiency virus (HIV). Babies may get infected during birth. Fomites such as towels have been implicated in transmission. LIFE CYCLE Life cycle of Trichomonas vaginalis is completed in a single host either male or female Trophozoites divide by binary fission. As cysts are not formed, the trophozite itself is the infective form. Incubation period is roughly 10 days. PATHOGENESIS It secretes cystine proteases, lactic acid, and acetic acid, which disrupt the glycogen levels and lower the pH of the vaginal fluid. It is an obligate parasite and cannot live without close association with the vaginal, urethral, or prostatic tissues. Parasite causes petechial hemorrhage (strawberry mucosa), metaplastic changes, and desquamation of the vaginal epithelium. Intracellular edema and so called chicken-like epithelium, is the most characteristic feature of trichomoniasis.  CLINICAL FEATURES Infection is often asymptomatic, particularly in males, although some may develop urethritis, epididymitis, and prostatitis. In females, it may produce severe pruritic vaginitis with an offensive, yellowish green, often frothy discharge, dysuria, and dyspareunia. Cervical erosion is common. Endometritis and pyosalpingitis are infrequent complications. Rarely, neonatal pneumonia and conjunctivitis have been reported in infants born to infected mothers. The incubation period of trichomoniasis is 4 days to 4 weeks. LABORATORY DIAGNOSIS Microscopic examination: Vaginal or urethral discharge is examined microscopically in saline wet mount preparation for characteristic jerky and twitching motility and shape. Culture: is considered as a 'gold standard' as well as the most sensitive (95%) method for the diagnosis of T. vaginalis infection. Serology: ELISA is used for demonstration of T. vaginalis antigen in vaginal smear Molecular method: (PCR) TREATMENT Simultaneous treatment of both partners is recommended. Metronidazole 2 g orally as a single dose or 500 mg orally twice a day for 7 days is the drug of choice. In patients not responding to treatment with standard regime, the dose of metronidazole may be increased or it may be administered parenterally. In pregnancy, metronidazole is safe in second and third trimesters. PROPHYLAXIS Avoidance of sexual contact with infected partners and use of barrier method during intercourse prevent the disease. Patient’s sexual partner should be tested for T. vaginalis when necessary.