Trichomonas
Name: trichomonas vaginitis
Synonyms: trichomoniasis, trich, trick
General description
An inflammation of the vaginal canal caused by a protozoan. It is considered to be a sexually transmitted disease. It causes vulvar itching and an odorous vaginal discharge.
Is it common?
In a general, low risk population, the incidence of trichomoniasis is probably less than 1%. In sexually transmitted disease clinics, however, trichomonas may represent from 10-50% of women presenting with vaginal symptoms.
Differentiating features
The vaginal discharge is often yellowish-green in color and is malodorous. It may be associated with vulvar itching and burning and redness and swelling. Microscopic examination of vaginal secretions in saline shows moving organisms. The trophozoites are about the size of a white blood cell with 3 flagella that cause the movement.
Culture grows out trichomonas vaginalis. Polymerase chain reaction testing (PCR) is specific for trichomonas. Spun urine can be used as a screening test but it is less sensitive (64% of those with positive cultures) than vaginal fluid exam (73% of those with positive cultures), but both used together pick up about 85% of those who are culture positive. In a study comparing 4 diagnostic techniques, 70 positives (8.7% of women attending an STD clinic) were identified:
Other features
The discharge produced is maloderous and can cause vulvar burning, itching and swelling similar to a candida (yeast) vaginitis. pH (acid measurement) of vaginal discharge is greater than 4.5. On vaginal speculum exam, skin bleeding points (petechiae) are present in the upper vagina and cervix in about 10% of cases.
Cause
Trichomonas vaginalis is a flagellate protozoa that is pear-shaped and about the size of a white blood cell. It has three flagella and reproduces by binary fision. It is pathogenic (disease producing) to the genitourinary tract. In women, it lives only in the vagina and the Skene's glands of the urethra. It can cause a urethritis (burning with urination) as well as a vaginitis. In men it can also cause a urethritis. It has been reported to be acquired by masturbation using the fingers and contracting the organism from baths, moist toilet seats and towels cannot be ruled out.
Unnecessary studies
Biopsy of the vagina or cervix. Colposcopy.
Natural history untreated
About 50% of women are assymptomatic carriers and the other 50% complain of vaginal discharge, odor, and vulvar itching and burning. Untreated it may progress to a urethritis or cystitis. It is seldom symptomatic before the onset of menses in a young girl (menarche). In pregnancy, the infection can be passed from a mother to a newborn daughter. In men, the infection can progress to prostatitis, urethritis, epididymitis and superficial penile ulcerations. In pregnancy, trichomoniasis is not felt to be associated with preterm labor. Goals of therapy (Rx) To eliminate the organism from the entire genitourinary tract. 1st choice therapy metronidazole (Flagyl®), 2 grams by mouth (usually 4, 500 mg tabs) for the woman and her partner(s).
Other therapies used
metronidazole 500 mg twice a day by mouth for 7 days.
Other nitroimazoles available in Europe such as nimorazole or ornidazole are also effective. It has also been suggested that the intravaginal application of the spermicide, nonoxynol-9, may have some effect against metronidazole resistant trichomonas although it would not be expected to era
dicate the organism in the urethra or Skene's glands. Other agents such as mebendazole (Vermox ®), and furazolidone (Furoxone ®) may be effective for treatment of metronidazole-resistant trichomoniasis.
Treatments to avoid
Topical metronidazole gel is not recommended because it is not absorbed well enough to produce blood levels that can eradicate trichomonas vaginalis in the Skene's periurethral glands and the urethra. Reason for RX choices: The 2 gram metronidazole dose has a 90-95% cure rate and good compliance since it is an all at once dose. The infection is not eradicable by other procedures and no other drugs are as effective. Metronidazole also works on bacterial vaginosis which often accompanies trichomoniasis. Metronidazole is also effective in treating male partners.
References Center for Disease Control 1998 Guidelines for Treatment of Sexually Transmitted Disease.
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