Partner Treatment and Reinfection Prevention for Trichomoniasis

A trichomonad dividing; the parasite multiplies by splitting
A trichomonad dividing; the parasite multiplies by splitting
A trichomonad clinging to a vaginal cell
A trichomonad clinging to a vaginal cell
  1. Why Partner Treatment Matters
  2. Expedited Partner Therapy (EPT)
  3. Who Counts as a Partner
  4. Telling a Partner
  5. Repeat Infection After Treatment
  6. Retesting After Treatment: What It Is and When
  7. Distinguishing Reinfection from Treatment Failure
  8. Nitroimidazole Resistance: Guideline Regimens
  9. Repeated Infections: What the Guideline Describes
  10. Key Research Papers
  11. Connections

Why Partner Treatment Matters

The 2021 CDC guideline states that concurrent treatment of all sex partners is vital for preventing reinfections, and that current partners should be referred for presumptive therapy (CDC 2021, PubMed PMID: 34292926). It also states that male partners of women with trichomoniasis are likely to have infection (CDC 2021, PubMed PMID: 34292926).

Repeat infection after treatment is common. A review gives repeat infection rates of 5-31% in the studies it cites, and names three possible sources of a positive test after treatment: reinfection from an untreated or infected baseline partner, infection from a new partner, or treatment failure (Kissinger 2015, PubMed PMID: 26242185). The guideline states that most recurrent infections likely result from reinfection (CDC 2021, PubMed PMID: 34292926).

Infection in men is often silent. The same review states that 77% of infected men are asymptomatic, and that infection may persist for months or even years in women but generally lasts less than 10 days in men (Kissinger 2015, PubMed PMID: 26242185). The guideline states that men with trichomoniasis sometimes have symptoms of urethritis, epididymitis or prostatitis (CDC 2021, PubMed PMID: 34292926). The review notes that telling patients to have their partners seek testing can be problematic because sensitive tests for men are not readily available (Kissinger 2015, PubMed PMID: 26242185).

Expedited Partner Therapy (EPT)

Expedited partner therapy (EPT) is described in the guideline as a harm-reduction strategy in which medications or prescriptions are provided to the patient, as allowable by law, and the patient passes them to sex partners without the health care provider having examined the partners (CDC 2021, PubMed PMID: 34292926).

For trichomoniasis, the guideline states that EPT might have a role in partner management and can be used in states where permissible by law, but that no partner management intervention has been demonstrated to be superior in reducing reinfection rates (CDC 2021, PubMed PMID: 34292926). It states that EPT is legal in the majority of states, that its status varies, and points to CDC's state-by-state information (CDC 2021, PubMed PMID: 34292926).

The trials behind that statement differ in their results. In a trial of 463 culture-positive women treated for trichomoniasis at a family planning clinic, randomized to standard partner referral, booklet-enhanced partner referral, or patient-delivered partner treatment, patient-delivered treatment did not result in more partners taking the medicine or lower follow-up rates than partner referral, but cost less (Kissinger 2006, PubMed PMID: 16531939). In a trial of 484 women randomized to partner self-referral, patient-delivered partner therapy, or public health disease intervention specialists delivering medication in the field, repeat infection at 1 and 3 months did not differ significantly between either intervention and self-referral; compared with the disease-intervention arm, the patient-delivered arm had a lower repeat infection rate at 1 month (5.8% versus 15%) (Schwebke 2010, PubMed PMID: 20453720). A review describes one randomized trial in which partner treatment with 2 g tinidazole gave a more than 4-fold reduction in repeat infections among infected women, while two studies using 2 g metronidazole for male partners found no effect or a borderline effect (Kissinger 2015, PubMed PMID: 26242185).

In a cohort of 252 women with HIV and trichomoniasis in three US cities, each given treatment to deliver to all reported partners, 75.4% of the 183 women with partners delivered it to all of them; not doing so was associated with multiple partners, being single, and having a partner unaware of the woman's HIV status (Gatski 2010, PubMed PMID: 20502393).

On what accompanies EPT, the guideline's general EPT guidance states that packaged oral medication is the preferred approach, because the efficacy of EPT using prescriptions has not been evaluated, obstacles can exist at the pharmacy level, and many persons (especially adolescents) do not fill prescriptions provided by a sex partner. It describes educational materials for the partner: treatment instructions, warnings about taking the medication (for example, if the partner is pregnant or has an allergy to it), general health counseling, and a statement advising that partners seek medical evaluation as soon as possible for HIV infection and any symptoms of STIs (CDC 2021, PubMed PMID: 34292926).

The guideline's recommended regimen for men with trichomoniasis is metronidazole 2 g orally in a single dose, with tinidazole 2 g orally in a single dose as the alternative for women and men (CDC 2021, PubMed PMID: 34292926).

Who Counts as a Partner

The guideline's trichomoniasis section speaks of treating all sex partners and of referring current partners for presumptive therapy; it does not set a look-back window for trichomoniasis (CDC 2021, PubMed PMID: 34292926). The 60-day window often seen in partner-notification guidance appears in the guideline's EPT guidance for chlamydia: EPT is to be offered routinely when the provider cannot ensure that all of a patient's sex partners from the previous 60 days will seek timely treatment, or for the most recent partner if the patient has not had sex during those 60 days (CDC 2021, PubMed PMID: 34292926).

Female partners: the guideline states that trichomonas is a relatively common infection among women who have sex with women, with prevalence higher than for chlamydia or gonorrhea, that direct transmission of trichomonas between female partners has been demonstrated, and that transmission can occur through infected vaginal fluids or fomites among women who have sex with women (CDC 2021, PubMed PMID: 34292926).

Abstinence: the guideline states that providers should advise persons with T. vaginalis infection to abstain from sex until they and their sex partners are treated (that is, when therapy has been completed and any symptoms have resolved), and that partners also should be advised to abstain until they and their sex partners have been treated and any symptoms have resolved (CDC 2021, PubMed PMID: 34292926).

Partners in persistent infection: for partners of people with persistent or recurrent trichomoniasis in whom nonadherence and reinfection are unlikely, the guideline states that no definitive data exist to guide treatment, but that partners might benefit from being evaluated and receiving treatment (CDC 2021, PubMed PMID: 34292926).

Telling a Partner

The guideline states that most people with trichomoniasis (70%-85%) have minimal or no genital symptoms and that untreated infections might last from months to years (CDC 2021, PubMed PMID: 34292926). A positive test therefore does not by itself show when, or from whom, an infection was acquired.

Several facts in the guideline bear on what a partner is told: the recommended regimen differs by sex (metronidazole 500 mg twice daily for 7 days for women, a single 2 g dose for men); both the person treated and the partners are advised to abstain until both have been treated and any symptoms have resolved; and repeat testing is recommended for women after treatment (CDC 2021, PubMed PMID: 34292926). Its general EPT guidance describes written educational materials that go with medication for a partner (see above) (CDC 2021, PubMed PMID: 34292926). Decisions about treatment belong with a clinician.

Repeat Infection After Treatment

Because of the high rate of reinfection among women treated for trichomoniasis, the guideline recommends retesting all sexually active women, regardless of whether they believe their sex partners were treated; a 2023 erratum to the guideline gives the interval as approximately 3 months after initial treatment (CDC 2021, PubMed PMID: 34292926; 2023 erratum, PubMed PMID: 36701253). If retesting at 3 months is not possible, the guideline states that clinicians should retest whenever persons next seek medical care within 12 months after initial treatment, and that data are insufficient to support retesting men after treatment (CDC 2021, PubMed PMID: 34292926).

Repeat infection figures: a review gives 5-31% in the studies it cites, and 18.3-36.9% among women with HIV in culture-based studies, noting that the true rate may be higher (Kissinger 2015, PubMed PMID: 26242185). In a trial among 270 women with HIV, all of whom were given 2 g metronidazole doses to deliver to their partners, repeat infection at 3 months was 11.0% (8 of 73) after the 7-day course versus 24.1% (19 of 79) after a single dose (Kissinger 2010, PubMed PMID: 21423852). In a trial of 623 HIV-uninfected, non-pregnant women, 11% (34 of 312) in the 7-day group and 19% (58 of 311) in the single-dose group were positive at the test-of-cure visit 4 weeks after treatment (Kissinger 2018, PubMed PMID: 30297322).

The review states that each possible source of a repeat positive test calls for a different approach: assuring that the original partners are treated where the cause is reinfection, and rescreening where the source is a new partner or treatment failure (Kissinger 2015, PubMed PMID: 26242185).

Retesting After Treatment: What It Is and When

Retesting after treatment means testing a treated woman again to detect persistent or repeat infection. For sexually active women the guideline's interval is approximately 3 months after initial treatment (see above) (CDC 2021, PubMed PMID: 34292926; 2023 erratum, PubMed PMID: 36701253). For women with HIV, the guideline recommends retesting 3 months after treatment and encourages NAAT because of the higher sensitivity of these tests (CDC 2021, PubMed PMID: 34292926).

Test choice: the guideline describes NAATs as highly sensitive, detecting more infections than wet-mount microscopy among women, and gives wet-mount sensitivity as 44%-68% compared with culture, falling to 20% within 1 hour after collection (CDC 2021, PubMed PMID: 34292926). For persistent or recurrent trichomoniasis, it describes culture as the preferred retest and states that a NAAT should not be done before 3 weeks after treatment completion because it might detect residual nucleic acid that is not clinically relevant; culture is also necessary for drug-susceptibility testing (CDC 2021, PubMed PMID: 34292926).

Pregnancy: the guideline states that symptomatic pregnant women, regardless of pregnancy stage, should be tested and treated, that clinicians should counsel them about the importance of partner treatment and condom use, and that the benefit of routine screening of asymptomatic pregnant women has not been established (CDC 2021, PubMed PMID: 34292926).

When a repeat infection occurs, the guideline states that its origin should be assessed, because most recurrent infections likely result from reinfection (CDC 2021, PubMed PMID: 34292926).

Distinguishing Reinfection from Treatment Failure

The guideline states that a recurrent infection can result from treatment failure (antimicrobial-resistant T. vaginalis or host-related problems), lack of adherence, or reinfection from an untreated sex partner, and that most recurrent infections likely result from reinfection (CDC 2021, PubMed PMID: 34292926).

Some studies found treatment failure to be the more common cause. A review describes a study of women with and without HIV in which a large proportion of repeat infections were attributed to treatment failure (no sexual exposure and no drug resistance), and states that resistance appears to play only a minor role in probable treatment failure (Kissinger 2015, PubMed PMID: 26242185). In the cohort of women with HIV described above, 10.3% were positive at a test-of-cure visit 6 to 12 days after treatment; of the 24 repeat infections, 21 (87.5%) reported adherence to medication and no sexual exposure, and the authors concluded that treatment failure was the most common probable cause (Gatski 2010, PubMed PMID: 20502393).

The guideline's regimens after treatment failure: for a woman who completed metronidazole 500 mg twice daily for 7 days and was reexposed to an untreated partner, a repeat course of the same regimen; if no reexposure occurred, metronidazole or tinidazole 2 g once daily for 7 days. For a man with persistent infection after a single 2 g dose who was reexposed, a repeat single 2 g dose; if not reexposed, metronidazole 500 mg twice daily for 7 days (CDC 2021, PubMed PMID: 34292926). The guideline also states that multidose oral metronidazole is more effective than single-dose treatment, particularly for women who are symptomatic or have a history of T. vaginalis infection (CDC 2021, PubMed PMID: 34292926).

Nitroimidazole Resistance: Guideline Regimens

The guideline states that metronidazole resistance occurs in 4%-10% of cases of vaginal trichomoniasis, that tinidazole resistance is less well studied but was present in 1% of infections in one study, and that more isolates have reported susceptibility to tinidazole than to metronidazole (CDC 2021, PubMed PMID: 34292926). A 2004 review states that at least 5% of clinical cases are caused by parasites resistant to metronidazole (Cudmore 2004, PubMed PMID: 15489348). Another review gives reported metronidazole resistance among mostly HIV-uninfected women of 2.2-9.6%, usually resolved with repeat metronidazole at the same or a higher dosage (Kissinger 2015, PubMed PMID: 26242185).

Susceptibility testing: for persistent infection not attributable to reexposure, the guideline states that clinicians should request a kit from CDC to perform drug-resistance testing, that CDC is experienced with susceptibility testing for nitroimidazole-resistant T. vaginalis and can provide guidance on treatment, and that an alternative regimen might be recommended on the basis of the results (CDC 2021, PubMed PMID: 34292926).

Regimens for resistant infection: the guideline lists metronidazole or tinidazole 2 g daily for 7 days for infections demonstrating in vitro resistance. After failure of that 7-day high-dose regimen, it describes two options with successful results for women: first, high-dose oral tinidazole 2 g daily plus intravaginal tinidazole 500 mg twice daily for 14 days; if that fails, high-dose oral tinidazole 1 g three times daily plus intravaginal paromomycin (4 g of 6.25% cream nightly) for 14 days (CDC 2021, PubMed PMID: 34292926).

The guideline states that alternative regimens might be effective but have not been systematically evaluated, and recommends consultation with an infectious disease specialist; clinical improvement has been reported with intravaginal boric acid but not with nitazoxanide (CDC 2021, PubMed PMID: 34292926).

Repeated Infections: What the Guideline Describes

For a repeat infection, the guideline states that its origin should be assessed (CDC 2021, PubMed PMID: 34292926), and a review describes matching the response to the source: assuring treatment of the original partners where reinfection is the cause, and rescreening where the source is a new partner or treatment failure (Kissinger 2015, PubMed PMID: 26242185).

Bacterial vaginosis: the guideline states that women with bacterial vaginosis are at higher risk for T. vaginalis infection (CDC 2021, PubMed PMID: 34292926). In the 2018 trial of single-dose versus 7-day metronidazole, bacterial vaginosis status had no significant effect on the relative risk (Kissinger 2018, PubMed PMID: 30297322). In a randomized trial of women with asymptomatic bacterial vaginosis, treatment and twice-weekly intravaginal metronidazole gel lengthened the time to an STI, a difference driven by fewer chlamydial infections (Schwebke 2007, PubMed PMID: 17547876).

Other STIs and HIV: the guideline states that testing for other STIs, including HIV, syphilis, gonorrhea and chlamydia, should be performed for persons with T. vaginalis infection (CDC 2021, PubMed PMID: 34292926). Among women with HIV, the guideline states that up to 53% have T. vaginalis infection, recommends screening at entry to care and at least annually, and lists metronidazole 500 mg twice daily for 7 days (CDC 2021, PubMed PMID: 34292926); in the trial in women with HIV, the 7-day course was more effective than the single dose (Kissinger 2010, PubMed PMID: 21423852). Women with HIV who were effectively treated were less likely to shed HIV vaginally 3 months after treatment than at baseline (relative risk 0.34) (Kissinger 2009, PubMed PMID: 19008776).

Prevention: the guideline states that among sexually active persons the best way to prevent genital trichomoniasis is consistent and correct use of condoms (external or internal), that partners of men who have been circumcised might have a somewhat reduced risk, and that douching is not recommended because it might increase the risk for vaginal infections, including trichomoniasis (CDC 2021, PubMed PMID: 34292926). It notes that the USPSTF recommends intensive behavioral counseling for all sexually active adolescents and for adults at increased risk for STIs and HIV (CDC 2021, PubMed PMID: 34292926). Condoms, screening and counseling are covered in more detail on the Prevention and Screening page.

Key Research Papers

  1. Kissinger P, Mena L, Levison J, et al. A randomized treatment trial: single versus 7-day dose of metronidazole for the treatment of Trichomonas vaginalis among HIV-infected women. J Acquir Immune Defic Syndr. 2010;55(5):565-571. — PubMed PMID: 21423852
  2. Kissinger P, Schmidt N, Mohammed H, et al. Patient-delivered partner treatment for Trichomonas vaginalis infection: a randomized controlled trial. Sex Transm Dis. 2006;33(7):445-450. — PubMed PMID: 16531939
  3. Workowski KA, Bachmann LH, Chan PA, et al. Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR Recomm Rep. 2021;70(4):1-187. — PubMed PMID: 34292926
  4. Schwebke JR, Desmond RA. A randomized trial of metronidazole in asymptomatic bacterial vaginosis to prevent the acquisition of sexually transmitted diseases. Am J Obstet Gynecol. 2007;196(6):517.e1-6. — PubMed PMID: 17547876
  5. Gatski M, Kissinger P. Observation of probable persistent, undetected Trichomonas vaginalis infection among HIV-positive women. Clin Infect Dis. 2010;51(1):114-115. — PubMed PMID: 20518674
  6. Muzny CA, Van Gerwen OT, Kissinger P. Updated guidance for Trichomonas vaginalis management in the United States. Expert Rev Anti Infect Ther. 2022;20(4):467-476. — Search PubMed — Note: no record matching this citation was found in PubMed or Crossref (checked October 2026); nothing on this page relies on it.
  7. Wendel KA, Workowski KA. Trichomoniasis: challenges to appropriate management. Clin Infect Dis. 2007;44(Suppl 3):S123-S129. — PubMed PMID: 17342665
  8. Cudmore SL, Delgaty KL, Hayward-McClelland SF, et al. Treatment of infections caused by metronidazole-resistant Trichomonas vaginalis. Clin Microbiol Rev. 2004;17(4):783-793. — PubMed PMID: 15489348
  9. Kissinger P, Amedee A, Clark RA, et al. Trichomonas vaginalis treatment reduces vaginal HIV-1 shedding. Sex Transm Dis. 2009;36(1):11-16. — PubMed PMID: 19008776
  10. Schwebke JR, Burgess D. Trichomoniasis. Clin Microbiol Rev. 2004;17(4):794-803. — PubMed PMID: 15489349
  11. Gatski M, Mena L, Levison J, et al. Patient-delivered partner treatment and Trichomonas vaginalis repeat infection among human immunodeficiency virus-infected women. Sex Transm Dis. 2010;37(8):502-505. — PubMed PMID: 20502393
  12. Schwebke JR, Desmond RA. A randomized controlled trial of partner notification methods for prevention of trichomoniasis in women. Sex Transm Dis. 2010;37(6):392-396. — PubMed PMID: 20453720
  13. Kissinger P. Trichomonas vaginalis: a review of epidemiologic, clinical and treatment issues. BMC Infect Dis. 2015;15:307. — PubMed PMID: 26242185
  14. Kissinger P, Muzny CA, Mena LA, et al. Single-dose versus 7-day-dose metronidazole for the treatment of trichomoniasis in women: an open-label, randomised controlled trial. Lancet Infect Dis. 2018;18(11):1251-1259. — PubMed PMID: 30297322
  15. Erratum: Vol. 70, No. RR-4. MMWR Morb Mortal Wkly Rep. 2023;72(4):107-108. — PubMed PMID: 36701253

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Connections