Trichomonas spp.

There are 3 species of Trichomonads found in humans of which 2 are normally harmless commensals, T. hominis and T.tenax and one T. vaginalis which is a serious sexually transmitted pathogen
Trichomonas vaginalis:
Morphology:
Trichomonas is a one-celled parasite that can live in the vagina, the cervix, or in the male lower genital tract. Under the microscope, this protozoan looks like a teardrop-shaped cell with a tail.. It is slightly larger than a white blood cell, Five flagella arise near the cytosome; four of these immediately extend outside the cell together, while the fifth flagellum wraps backwards along the surface of the organism. The functionality of the fifth flagellum is not known. In addition, a conspicuous barb-like axostyle projects opposite the four-flagella bundle; the axostyle may be used for attachment to surfaces and may also cause the tissue damage noted in trichomoniasis infections.
While T. vaginalis does not have a cyst form, organisms can survive for up to 24 hours in urine, semen, or even water samples. Combined with an ability to persist on fomites with a moist surface for 1 to 2 hours, T. vaginalis is among the most durable protozoan trophozites. Women with trichomonas usually have accompanying discharge or irritation.
Life Cycle:
T. vaginalis trophozoite reside on the mucosal surface of the vagina in infected woman. The growing trophozoite multiplies by longitudinal binary fission and feed on local bacteria and leukocytes. T. vaginals trophozoite thrives in a slightly alkaline or slightly acid PH environment. The most common infection site of T. vaginalis in males is the prostate gland region and the epithelium of the urethra. The detailed life cycle in the male host is unknown.
Clinical features:
Approximately 20% of infected persons are asymptomatic carriers (asymptomatic cases most frequently in men).It is a frequent inhabitant of the human vagina and of the male genital tract localized in the prostate and urethra. The organism is capable of surviving on dry materials for a few hours and on moist materials for longer period.
-Infection in male is often asymptomatic although at some time, it is
Associated with urethritis which represents the most common symptomatic Presentation in male. Asymptomatic carriers serve as a reservoir for transmission and also remain at risk for developing disease.
-Vaginitis may be complicated by bacterial, fungal (yeast) or spirochetal
infection. The chief complains are leukorrhea (pus cells in urine) and
dysuria, excessive discharge that is creamy yellowish to greenish and frothy due to the gases produced vaginal bacteria and sometimes the discharge may have a bad odor (foul smell).
-The onset of symptoms, such as intense vaginal and vulvar pruritis, and
discharge is often sudden and occurs during or after menstruation.
-As above, urticaria and acute vulvulitis may also occur. It is considered
that the disease is more annoying than disabling.
-In general, it causes non-gonococcal urethritis or tetracyclin-resistant
urethritis in male.
-The organism dose not infect the epithelium, it is found loose in the vaginal cavity or adherent to the epithelium.
-There are certain factors that play a role in the pathogenesis of the parasite
which include; age, sex, glycogen contents, pH, pregnancy, seminal fluid
and number of parasites needed for infection.
-The essential factors for growth of T.vaginalis are:
1- Presence of glycogen in vaginal cells.
2- pH of vagina (optimal pH for growth of T.vaginalis is 5.5).
the incidence of T.vaginalis infection is high among mature females. This explained by the changes in the pH and glycogen amount of vagina.
-In mature female (15-40 years), the normal vaginal pH is acidic (4-4.5),
this acidity maintains by certain type of bacteria called Dauder lein’s
lactobacillus which lives on expense of the high amount of glycogen in the vaginal cells, and as a biproducts, it produces lactic acid which makes
vaginal medium acidic (4-4.5) in the mature females. Also, there is a highest peak of sexual activity, so, the seminal fluid can elevate the acidity of vagina to 5.5 (optimal pH).
-Female of this age (15-40 years) need less than 10 parasites to become
infected, whereas the male need 10 parasites to become infected.
-Beacuse of both T.vaginalis and bacterial flora (lactobacilli) live on
glycogen and acidic pH, therefore, during infection with T.vaginalis , no
chance for bacteria to live and the pH of vagina rise to 5.5 (optimal pH for T.vaginalis growth) beacuse no lactic acid production.
-The glycogen content of the epithelium is high and increases during
pregnancy, thus pregnant female is more liable for infection.
-Using of antibiotics and presence of other infection will elevate the pH of vagina or urethra to 5.5 and can help in producing infection.
-In other groups (immature female , menopause and male) because of scanty or no glycogen due to the hormonal changes, this bacteria (lactobacillus) cannot live. Therefore, the pH will rise and be high (about 7) and whole bacterial flora changes to other flora, and because of this high pH (7) and scanty glycogen, T.vaginalis loses its viability and can not live in this environment (T.vaginalis loses its viability below the pH of 3.8 and above pH of 7.5).
-Infection has also been associated with premature rupture of ameniotic
membrane, premature birth and post-hysterectomy cuff infection. More
recently, it has been implicated as a factor in transmission of HIV.
-Neonate can acquire the organism during passage through infected birth
canal. It is estimated that 2-7% of female babies acquire trichomoniasis by directed vulvovaginal contamination. Reports have been also documented T.vaginalis as a cause of neonatal pneumonia.
Laboratory diagnosis
The diagnosis for this organism is commonly based on the examination of wet preparation of vaginal and urethral discharges , prostatic secretions and urine sediments. The presence of actively motile organism with jerky
motility is diagnostic.
Treatment
The treatment of choice for T.vaginalis infection is metronidazole . All
sexual partners of infected individuals should also receive treatment. This
medication should not be used during pregnancy unless the benefits of
treatment outweigh the risks to the fetus. The presenting complaint in female patients is usually a vaginal discharge, which often has a foul smelling , greenish-yellow liquid vaginal discharge . in moderate to severe cases, there may be complaints of local irritation or a burning and itching sensation in the vulva, vagina.