> Table of Contents > Trichomoniasis
Michael Arnold, MD, CDR, MC
Joshua R. Beer, DO
image BASICS
  • Sexually transmitted urogenital infection caused by a pear-shaped, parasitic protozoan
  • Causes vaginitis/urethritis in women, nongonococcal urethritis in men
  • In pregnancy, increases risk of preterm labor, preterm premature rupture of membranes, small for gestational age infant, and possibly stillbirth
  • Synonym(s): trich; trichomonal urethritis
  • Affects >120 million women worldwide. The most common curable sexually transmitted infection (STI) worldwide (1).
  • Estimated 1.1 million new cases annually in the United States
  • 10-25% of vaginal infections
  • 1-17% of cases of NGU in males; reported prevalence among men without urethritis ranges from 0% to 8%
  • Predominant age: middle-aged adults
    • Rare until onset of sexual activity
    • Common in postmenopausal women; age is not protective and long-term carriage is possible.
  • Women have higher prevalence (1.5 to 4.4 times more than men) and are more commonly symptomatic (2).
Pediatric Considerations
Rare in prepubertal children; diagnosis should raise concern of sexual abuse.
  • 3.1% of all U.S. women age 25 to 49 years; 1.5% of U.S. women age 15 to 24 years
  • Racial disparity demonstrated
    • 1.3% of white, non-Hispanic women
    • 1.8% of Mexican American women
    • 13.3% of black, non-Hispanic women (2)
  • Trichomonas vaginalis: a pear-shaped, flagellated, parasitic protozoan
  • Grows best at 35-37°C in anaerobic conditions at pH of 5.5 to 6.0
  • STI, but nonsexual transmission is possible because organism can survive several hours in moist environment.
No known genetic considerations
  • Multiple sexual partners
  • Unprotected intercourse
  • Lower socioeconomic status
  • Other STIs
  • Untreated partner with previous infection
  • Use of douching or feminine powders
  • Use of male or female condoms
  • Limiting numbers of sexual partners
  • Male circumcision may be protective (3)[B].
  • Other STIs, including HIV
  • Bacterial vaginosis
  • Women
    • Vaginal erythema
    • Yellow-green, frothy, malodorous vaginal discharge
    • Cervical petechiae (strawberry cervix; seen in ˜ 10% of patients)
  • Men: penile discharge, spontaneous and with expression
  • Women (other vaginitides)
    • Bacterial vaginosis
    • Vaginal candidiasis
    • Chlamydial infection
    • Gonorrheal infection
  • Men (other urethritides)
    • Chlamydial infection
    • Gonorrheal infection
Initial Tests (lab, imaging)
  • Wet mounts of vaginal or urethral discharge: direct visualization of motile trichomonads. Most common diagnostic method since inexpensive and available
    • Sensitivity: 60-70%; declines rapidly within 1 hour from collection
    • Specificity: 99.8%
  • Culture: sensitivity: >95%, specificity >99%; takes 4 to 7 days for growth
  • Nucleic acid amplification test (NAAT)
    • Gold standard for diagnosis (4)
    • Sensitivity and specificity 95-99%
    • FDA approved for vaginal, endocervical, or female urine specimens
    • Results in 1 hour
    • Limited clinical availability
  • Antigen detection
    • ELISA and direct fluorescent antibody tests: sensitivity of 80-90%
    • Limited clinical availability
Follow-Up Tests & Special Considerations
Detection on cervical Papanicolaou smear
  • Treat since highly specific (97-99%)
  • Not effective trichomonas screening test given sensitivity as low as 60%
Diagnostic Procedures/Other
Detection on self-obtained sample with DNA probe assay with specificity >98%
  • Symptomatic individuals require treatment.
  • Sexual partners should be treated presumptively.
  • Patients should abstain from sexual intercourse during treatment and until they are asymptomatic.
The nitroimidazole class is only known effective antimicrobial treatment. If metronidazole resistance is suspected, use tinidazole (5)[A].
First Line
  • Metronidazole: 2 g PO, 1 dose (6)[A]
    • FDA pregnancy risk Category B
    • Cure rate: 84-98%
  • Tinidazole: 2 g PO, 1 dose (6)[A]
    • FDA pregnancy risk Category C
    • Abstain from breastfeeding during treatment and for 3 days after the dose.
    • More expensive
    • Reaches higher levels in genitourinary tract
    • Cure rate: 92-100%
Second Line
  • Metronidazole: 500 mg PO BID for 7 days
    • Only if still symptomatic after initial treatment
    • Considered first line in HIV-positive individuals
  • Can dose with metronidazole or tinidazole 2 g daily for 7 days if infection persists
  • May consider IV dosing of metronidazole based on case report that demonstrated cure after multiple failed oral regimens
Pregnancy Considerations
Metronidazole is effective for trichomoniasis infection during pregnancy but may increase the risk of preterm and low-birth-weight babies.
  • Studies showed risk in patients receiving four times the standard dosing.
  • Trichomoniasis is also associated with prematurity.
  • Multidrug-resistant organism
  • Patient allergy to metronidazole: Desensitization to metronidazole is recommended.
  • Limited clinical trials assessing effectiveness of alternative therapies (4)
  • Intravaginal metronidazole gel is not effective.
  • Suggested alternative therapies based on small number of case reports
    • Paromomycin 6.25% cream
    • Povidone-iodine douche
    • Boric acid intravaginally
    • Furazolidone intravaginally

See “Additional Therapies.”
  • If symptoms persist after initial treatment, repeat wet mount or other testing.
  • Retest women for T. vaginalis recommended within 3 months of treatment. Data insufficient for retesting men (6)[A]
  • HIV-positive patients should be screened for trichomonas at time of HIV diagnosis and at least annually (6)[A].
  • Abstain from alcohol during treatment and for 24 hours following last dose of metronidazole or 48 to 72 hours following last dose of tinidazole due to disulfiram-like reaction.
Educate about the sexually transmitted aspect.
  • Advise patient to notify sexual partner to be treated.
  • Discuss STI prevention—condom use can prevent recurrence.
  • Abstain from intercourse while undergoing treatment; use condoms if abstention is not feasible.
  • Avoid alcohol during treatment with metronidazole or tinidazole.
  • Excellent
  • Usually eliminated after one course of antibiotics
1. World Health Organization. Prevalence and incidence of selected sexually transmitted infections, Chlamydia trachomatis, Neisseria gonorrhoeae, syphilis and Trichomonas vaginalis. Methods and results used by WHO to generate 2005 estimates. World Health Organization Web site. http://www.who.int/reproductivehealth/publications/rtis/9789241502450/en/. Accessed December 10, 2015.
2. Sutton M, Sternberg M, Koumans EH, et al. The prevalence of Trichomonas vaginalis infection among reproductive-age women in the United States, 2001-2004. Clin Infect Dis. 2007;45(10): 1319-1326.
3. Sobngwi-Tambekou J, Taljaard D, Nieuwoudt M, et al. Male circumcision and Neisseria gonorrhoeae, Chlamydia trachomatis and Trichomonas vaginalis: observations after a randomised controlled trial for HIV prevention. Sex Transm Infect. 2009;85(2): 116-120.
4. Muzny CA, Schwebke JR. The clinical spectrum of Trichomonas vaginalis infection and challenges to management. Sex Transm Infect. 2013;89(6): 423-425.
5. Seña AC, Bachmann LH, Hobbs MM. Persistent and recurrent Trichomonas vaginalis infections: epidemiology, treatment and management considerations. Expert Rev Anti Infect Ther. 2014;12(6):673-685.
6. Workowski KA, Bolan GA. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep. 2015;64(RR-03):1-137.
Additional Reading
  • Allsworth JE, Ratner JA, Peipert JF. Trichomoniasis and other sexually transmitted infections: results from the 2001-2004 National Health and Nutrition Examination Surveys. Sex Transm Dis. 2009;36(12):738-744.
  • Fastring DR, Amedee A, Gatski M, et al. Cooccurrence of Trichomonas vaginalis and bacterial vaginosis and vaginal shedding of HIV-1 RNA. Sex Transm Dis. 2014;41(3):173-179.
  • Forna F, Gülmezoglu AM. Interventions for treating trichomoniasis in women. Cochrane Database Syst Rev. 2003;(2):CD000218.
  • Gülmezoglu AM, Azhar M. Interventions for trichomoniasis in pregnancy. Cochrane Database Syst Rev. 2011;(5):CD000220.
  • Hale T. Medications and Mothers' Milk: A Manual of Lactational Pharmacology. 14th ed. Amarillo, TX: Hale Publishing; 2010.
  • Hawkins I, Carne C, Sonnex C, et al. Successful treatment of refractory Trichomonas vaginalis infection using intravenous metronidazole. Int J STD AIDS. 2015;26(9):676-678.
  • Helms DJ, Mosure DJ, Secor WE, et al. Management of Trichomonas vaginalis in women with suspected metronidazole hypersensitivity. Am J Obstet Gynecol. 2008;198(4):370.e1-370.e7.
  • Kirkcaldy RD, Augostini P, Asbel LE, et al. Trichomonas vaginalis antimicrobial drug resistance in 6 US cities, STD Surveillance Network, 2009-2010. Emerg Infect Dis. 2012;18(6):939-943.
  • Klebanoff MA, Carey JC, Hauth JC, et al. Failure of metronidazole to prevent preterm delivery among pregnant women with asymptomatic Trichomonas vaginalis infection. N Engl J Med. 2001;345(7): 487-493.
  • McClelland RS, Sangare L, Hassan WM, et al. Infection with Trichomonas vaginalis increases the risk of HIV-1 acquisition. J Infect Dis. 2007;195(5): 698-702.
  • Meites E. Trichomoniasis: the “neglected” sexually transmitted disease. Infect Dis Clin North Am. 2013;27(4):755-764.
  • Miller M, Liao Y, Gomez AM, et al. Factors associated with the prevalence and incidence of Trichomonas vaginalis infection among African American women in New York City who use drugs. J Infect Dis. 2008; 197(4):503-509.
  • Saperstein AK, Firnhaber GC. Clinical inquiries. Should you test or treat partners of patients with gonorrhea, chlamydia, or trichomoniasis? J Fam Pract. 2010;59(1):46-48.
  • Satterwhite CL, Torrone E, Meites E, et al. Sexually transmitted infections among US women and men: prevalence and incidence estimates, 2008. Sex Transm Dis. 2013;40(3):187-193.
  • Silver BJ, Guy RJ, Kaldor JM, et al. Trichomonas vaginalis as a cause of perinatal morbidity: a systematic review and meta-analysis. Sex Transm Dis. 2014;41(6):369-376.
  • Wendel KA, Workowski KA. Trichomoniasis: challenges to appropriate management. Clin Infect Dis. 2007;44(Suppl 3):S123-S129.
  • Wiese W, Patel SR, Patel SC, et al. A meta-analysis of the Papanicolaou smear and wet mount for the diagnosis of vaginal trichomoniasis. Am J Med. 2000;108(4):301-308.
  • A59.9 Trichomoniasis, unspecified
  • A59.03 Trichomonal cystitis and urethritis
  • A59.01 Trichomonal vulvovaginitis
Clinical Pearls
  • Both partners need to be treated for trichomoniasis.
  • Retest women within 3 months of treatment.
  • Avoid alcohol during treatment with standard agents.
  • Treatment does not reduce risk of adverse pregnancy outcomes.
  • Male circumcision may be protective.
  • Annual screening recommended for HIV-positive patients.
  • Not a nationally notifiable condition