| TrichomoniasisDefinition - Trichomoniasis is a sexually transmitted disease (STD) caused by Trichomonas vaginalis, one of the most prevalent protozoal parasites in the U.S.
- T. vaginalis is a pathogen of the genitourinary tract and a major cause of symptomatic vaginitis.
 Epidemiology - Incidence
- In the U.S.: ~7.4 million new cases each year in women and men
- Most common curable STD among young, sexually active women
- Age
- Most common among young and middle-aged adults
- Sex
- Both genders are affected, but women are more commonly symptomatic.
Risk Factors - Multiple sexual partners
- Unsafe sexual practices
- Infection with other STD agents
Etiology - T. vaginalis is a pear-shaped, actively motile organism.
- Measures ~10 × 7 μm
- Replicates by binary fission
- Inhabits the lower genital tract of females and the urethra and prostate of males
- Transmission
- Person-to-person venereal transmission accounts for virtually all cases.
- Incubation period: 5–28 days (in women)
- Most men are asymptomatic.
Associated Conditions Symptoms & Signs - Men
- Usually asymptomatic
- Some develop urethritis.
- Mild discharge
- Dysuria
- Burning after ejaculation
- A few have epididymitis or prostatitis.
- Women
- Usually symptomatic
- Malodorous, frothy vaginal discharge (often yellow)
- Vulvar erythema and itching
- Dysuria or urinary frequency (in 30–50% of patients)
- Dyspareunia
Differential Diagnosis Diagnostic Approach - The diagnosis is suggested by history and physical examination.
- The diagnosis is made by microscopic examination of vaginal, urethral, or prostatic secretions.
Laboratory Tests - Microscopic examination
- T. vaginalis can be recovered from the urethra of both males and females and is detectable in males after prostatic massage.
- Wet mounts of vaginal or prostatic secretions
- Conventional means of diagnosis
- Detects motile trichomonads
- However, sensitivity of only 50–60% in routine evaluations of vaginal secretions
- Direct immunofluorescent antibody staining is more sensitive (70–90%) than wet-mount examinations.
- Culture
- Most sensitive means of detection
- Takes 3–7 days
- Facilities for culture not generally available
Imaging Diagnostic Procedures Treatment Approach - Treat patients and all of their sexual partners (even if asymptomatic) with antibiotics.
- Reinfection often accounts for apparent treatment failures.
Specific Treatments Pharmacologic therapy- Metronidazole: single 2-g dose or 500 mg bid for 7 days
- Mainstay of treatment in non-pregnant and pregnant patients
- Tinidazole: single 2-g dose
- Effective, but not available in U.S.
- Alternatives to metronidazole for treatment during pregnancy
- Not readily available
- Clotrimazole vaginal suppositories
- 100-mg nightly for 2 weeks
- May cure some infections
- For persistent symptomatic urethritis in males after therapy for nongonococcal urethritis
- Consider metronidazole therapy for possible trichomoniasis.
- Management of sexual partners
- All sexual partners should be treated concurrently.
- Patients should be instructed to avoid sex until they and their partners are cured (i.e., when therapy has been completed and patients and partners are asymptomatic).
Resistant infections- Treatment failure
- Repeated treatment failure
Monitoring - Follow-up is unnecessary for men and women who become asymptomatic after treatment or who are asymptomatic initially.
- Persistent symptoms
- Causes include:
- Noncompliance with therapy
- Reinfection
- Infection with a resistant organism
- Patient should be re-treated (see Specific Treatments).
Complications - Vaginal trichomoniasis has been associated with adverse pregnancy outcomes, including:
- Premature rupture of membranes
- Preterm delivery
- Low birth weight
- Vaginal trichomoniasis may increase rates of acquisition and transmission of HIV infection.
Prognosis - Prognosis is excellent with treatment.
- Strains of T. vaginalis with high-level resistance to metronidazole have been encountered but are uncommon.
- Patients remain at risk for reinfection.
Prevention - All sexual partners must be treated concurrently to prevent reinfection, especially from asymptomatic males.
- Condom use can prevent infection.
ICD-9-CM - 007.3 Intestinal trichomoniasis
- 131.0_ Urogenital trichomoniasis, (specific site specified by fifth digit)
- 131.8 Trichomoniasis of other specified sites
- 131.9 Trichomoniasis, unspecified
See Also Internet Sites General Bibliography - Carr PL et al: "Shotgun" versus sequential testing. Cost-effectiveness of diagnostic strategies for vaginitis. J Gen Intern Med 20:793, 2005 [PMID:16117745]
- Centers for Disease Control and Prevention: Sexually transmitted diseases treatment guidelines 2002. MMWR Recomm Rep 51(RR-6):1, 2002
- Hager WD: Treatment of metronidazole-resistant Trichomonas vaginalis with tinidazole: case reports of three patients. Sex Transm Dis 31:343, 2004 [PMID:15167642]
- Landers DV et al: Predictive value of the clinical diagnosis of lower genital tract infection in women. Am J Obstet Gynecol 190:1004, 2004 [PMID:15118630]
- Petrin D et al: Clinical and microbiological aspects of Trichomonas vaginalis. Clin Microbiol Rev 11:300, 1998 [PMID:9564565]
- Sobel JD: Vaginitis. N Engl J Med 337:1896, 1997 [PMID:9407158]
- This topic is based on Harrison’s Principles of Internal Medicine, 16th edition, chapter 199, Protozoal Intestinal Infections and Trichomoniasis by PF Weller.
PEARLS - Consider a diagnosis of trichomoniasis in any woman with vaginal discharge (particularly if malodorous), itching, or urinary symptoms.
- Treat patients and all sexual partners concurrently to prevent reinfection.
- Test for other STDs (e.g., gonorrhea, chlamydial infection, HIV infection), and counsel patients about safer sexual practices.
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