Trichomoniasis

Trichomoniasis is a very common sexually transmitted disease (STD) caused by a tiny protozoan parasite called Trichomonas vaginalis. Trichomoniasis is usually spreads during sex, but can also be spread by sharing wet towels or washers. Trichomoniasis mostly affects women, but men can get it too. Most people who have trichomoniasis do not have any symptoms.

Trichomoniasis is the most common curable STD (sexually transmitted disease). In the United States, an estimated 3.7 million people have the infection ¹. However, only about 30% develop any symptoms of trichomoniasis. Trichomoniasis is more common in women than in men. Older women are more likely than younger women to have been infected with trichomoniasis.

Although symptoms of trichomoniasis vary, most people who have the Trichomonas vaginalis parasite cannot tell they are infected. Your doctor or sexual health clinic can test for and treat trichomoniasis.

Clinical manifestations in symptomatic pubertal or postpubertal females may include a diffuse foul-smelling (smelly fishy odor) vaginal discharge and vulvovaginal itch and irritation. Pain with urination or sexual intercourse and, less often, lower abdominal pain can occur. Vaginal discharge may be any color, but classically is yellow-green, frothy, and malodorous. The vulva and vaginal mucosa can be reddish and swollen. The cervix can be inflamed and sometimes is covered with numerous punctate cervical hemorrhages and swollen papillae, referred to as “strawberry” cervix. This finding occurs in less than 5% of infected females but is highly suggestive of trichomoniasis. Clinical manifestations in symptomatic men include urethritis (urethra inflammation) and, rarely, epididymitis or prostatitis. Reinfection is common, and resistance to treatment is rare but increasing. Rectal infections are uncommon, and oral infections have not been described.

The prevalence of Trichomonas vaginalis infection in the United States is estimated to be 2.3 million (3.1%) among women ages 14-49, based on a nationally representative sample of women who participated in National Health and Examination Survey (NHANES) 2001–2004. The following are other findings from this study ²:

• An estimated 3.7 million women and men are infected with Trichomonas vaginalis in the United States ³
• Most women found to have trichomoniasis (85%) reported no symptoms.
• Women with no history of sexual intercourse can still be affected by trichomoniasis (1.0%), as can pregnant women (3.2%), and women who have ever been pregnant (4.1%).
• African American women had a prevalence of 13.3%, white women prevalence of 1.3%, and Mexican American women prevalence of 1.8%.
• Prevalence of trichomoniasis increases with age and lifetime number of sexual partners among African American women.

It is not possible to diagnose trichomoniasis based on your symptoms alone. For both men and women, your doctor or sexual health care provider can examine you and get a laboratory test to diagnose trichomoniasis.

Trichomoniasis can be cured with a single dose of prescription antibiotic medication (either metronidazole or tinidazole or or secnidazole), pills which can be taken by mouth. It is okay for pregnant women to take this medication. Some people who drink alcohol within 24 hours after taking this kind of antibiotic can have uncomfortable side effects.

People who have been treated for trichomoniasis can get it again. About 1 in 5 people get infected again within 3 months after treatment. To avoid getting reinfected, make sure that all of your sex partners get treated too, and wait to have sex again until all of your symptoms go away (about a week). Get checked again if your symptoms come back. You can reduce your risk of infection by using condoms correctly every time you have sex.

If your symptoms don’t go away after treatment, talk to your doctor or sexual health worker.

Without treatment, trichomoniasis can last months, or even years. Trichomoniasis can cause premature labor, low birth weight, or increase your risk of getting HIV, the virus that causes AIDS.

Trichomoniasis key facts

• Trichomoniasis can be asymptomatic in men and women, and may persist silently for years.
• Untreated trichomoniasis is associated with adverse pregnancy outcomes such as premature rupture of the membranes, preterm delivery, and low birthweight infants.
• Douching may worsen vaginal discharge in patients with trichomoniasis.
• Alcohol consumption is contraindicated with metronidazole and tinidazole.
• Transmission Issues:
  • Trichomoniasis is almost always sexually transmitted.
  • Sex partners should be treated.
  • Patients should abstain from intercourse until they and their sex partners are cured (about 7 days).
  • Trichomoniasis has been associated with increased susceptibility to HIV acquisition and transmission.
• Risk Reduction:
  • Individualize risk-reduction plans with each patient.
  • Prevention strategies include abstinence, mutual monogamy with an uninfected partner, use of condoms, and limiting the number of sex partners.
  • Latex condoms, when used consistently and correctly, can reduce the risk of transmission of Trichomonas vaginalis.
  • Douching should be avoided since it increases the risk for trichomoniasis.
  • Male circumcision reduces the risk of trichomoniasis.

Figure 1. Trichomonas vaginalis

Footnote: Trichomonas vaginalis is a pear-shaped flagellated protozoan parasitic organism that is approximately 10 by 7 micrometers. The organism achieves a quivering motion via the anterior flagella and the undulating membrane. After attaching to vaginal epithelial cells, the organism takes on a more ameboid-like appearance.

[Source ⁴]

Trichomoniasis in men

Trichomonas vaginalis may cause up to 11% to 13% of nongonococcal urethritis (NGU) in males, but urethral infection in males is frequently asymptomatic ⁵. Men with Trichomonas vaginalis infection may also present with prostatitis or epididymitis ⁶.

Trichomoniasis rarely causes symptoms in men. When men do have signs and symptoms, however, they might include:

• Irritation inside the penis
• Burning with urination or after ejaculation
• Discharge from the penis

How does trichomoniasis affect a pregnant woman and her baby?

Pregnant women with trichomoniasis are more likely to have their babies too early (preterm delivery) ⁷. Also, babies born to infected mothers are more likely to have a low birth weight (less than 5.5 pounds) ⁸.

How do you get trichomoniasis?

The Trichomonas vaginalis parasite passes from an infected person to an uninfected person during sex. In women, the most commonly infected part of the body is the lower genital tract (vulva, vagina, cervix, or urethra). In men, the most commonly infected body part is the inside of the penis (urethra). During sex, the parasite usually spreads from a penis to a vagina, or from a vagina to a penis. Trichomoniasis can also spread from a vagina to another vagina. It is not common for the Trichomonas vaginalis parasite to infect other body parts, like the hands, mouth, or anus. It is unclear why some people with the trichomoniasis infection get symptoms while others do not. It probably depends on factors like a person’s age and overall health. Infected people without symptoms can still pass the infection on to others.

Resumption of Sexual Activity

Patients should be instructed to avoid sex until they and their sex partners have been treated, and until they no longer have any symptoms of trichomoniasis. This usually takes about 7 days.

Post-Treatment Follow-Up

All sexually active women who are diagnosed and treated for Trichomonas vaginalis infection (including pregnant women and women with HIV infection) should be retested 3 months after initial treatment to evaluate the possibility of reinfection. Retesting in men is not routinely recommended.

Trichomoniasis symptoms

About 70% of infected people with trichomoniasis do not have any signs or symptoms. When trichomoniasis does cause symptoms, they can range from mild irritation to severe inflammation. Some people with symptoms get them within 5 to 28 days after being infected. Others do not develop symptoms until much later. Symptoms can come and go.

Trichomoniasis symptoms in men

Men don’t usually get symptoms from trichomoniasis, but there may be a discharge from the penis, or pain when urinating ⁹.

Men with trichomoniasis may notice:

• Itching or irritation inside the penis;
• Burning after urination or ejaculation;
• Discharge from the penis.

Trichomoniasis in women

Women with trichomoniasis may notice:

• Itching, burning, redness or soreness of the genitals;
• Vaginal itching or burning;
• Pain during sex;
• Discomfort with urination;
• Pain low in the tummy;
• A change in their vaginal discharge (i.e., thin discharge or increased volume) that can be clear, frothy, white, yellowish, greyish or greenish with an unusual fishy smell.

Having trichomoniasis can make it feel unpleasant to have sex, but many women are asymptomatic ¹⁰. Without treatment, the infection can last for months or even years.

Chronic Trichomonas vaginalis infection may be associated with minimal vaginal discharge, mild itch and/or pain during sex (dyspareunia) ¹⁰. The presence of cervical punctate hemorrhages (Figure 2), often referred to as a “strawberry cervix,” strongly suggests a diagnosis of trichomoniasis, but this occurs in fewer than 5% of women with trichomoniasis ¹⁰, ¹¹.

Figure 2. Trichomoniasis and Cervical Petechiae (“strawberry cervix”)

Footnote: This photograph shows multiple petechiae on the cervix of a women with trichomoniasis. This manifestation in a woman with vaginal discharge strongly suggests a diagnosis of trichomoniasis and is often referred to as a ‘strawberry cervix‘.

[Source ⁴ ]

Trichomoniasis in pregnancy

Infection with Trichomonas vaginalis in pregnant women is associated with both obstetrical and gynecologic adverse outcomes, including low birth weight, premature rupture of membranes (PPROM) and preterm labor; trichomoniasis in pregnancy increases the risk of preterm birth by about 30% ¹², ¹³, ¹⁴. Neonatal trichomoniasis is unusual but can occur ¹⁵, ¹⁶.

Trichomoniasis in people with HIV

Among women with HIV, more than half are coinfected with Trichomonas vaginalis, and they have been shown to have an increased risk for pelvic inflammatory disease (PID) and for shedding of HIV in the genital tract ¹⁷, ¹⁸. Antiretroviral therapy appears to lessen the potentiating effects of trichomoniasis infections on HIV transmission risk ¹⁷. Infection with HIV does not make a woman more likely to have persistent or recurrent trichomoniasis ¹⁹.

Trichomoniasis causes

Trichomoniasis is caused by Trichomonas vaginalis, which is a single-celled flagellated anaerobic protozoan parasite, a type of tiny parasite that travels between people during sexual intercourse. The incubation period between exposure and infection is unknown, but it’s thought to range from five to 28 days.

Trichomonas vaginalis is the only known protozoan parasite that infects the genital tract. Trichomonas vaginalis has four anterior flagella and one flagellum embedded in an undulating membrane (Figure 1) ²⁰. The flagella are responsible for the jerky motility of this organism that is seen under a microscope. After attaching to vaginal epithelial cells, this globular, pear-shaped organism transforms into a thin, flat, ameboid shape ²¹. Trichomoniasis is almost always sexually transmitted; fomite transmission is extremely rare. T. vaginalis may persist for months to years in epithelial crypts and periglandular areas of the genital tract ²⁰. Distinguishing persistent, subclinical infection from remote sexual acquisition is not always possible.

Risk factors for trichomoniasis

Investigators have identified multiple risk factors associated with trichomoniasis that include the following ²²:

• Older age
• Multiple sex partners
• Drug use (marijuana, crack cocaine, alcohol, cigarettes)
• Sex without a condom
• Presence of sexually transmitted infections (STIs) at baseline
• Low socioeconomic status
• Douching
• Black race.

Trichomoniasis complications

Trichomoniasis can increase the risk of getting or spreading other sexually transmitted infections (STIs). For example, trichomoniasis can cause genital inflammation that makes it easier to get infected with human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS), or to pass the HIV virus on to a sex partner ²³.

Pregnant women who have trichomoniasis might:

• Deliver too early (prematurely)
• Have a baby with a low birth weight
• Give the infection to the baby as the baby passes through the birth canal

Trichomoniasis is also associated with an increased risk of cervical or prostate cancer.

Untreated, trichomoniasis infection can last for months to years.

Trichomoniasis prevention

The only way to avoid STDs (sexually transmitted diseases) is to not have vaginal, anal, or oral sex. The best way to avoid trichomoniasis is by using condoms every time you have sex. Safe sex also helps stop the spread of other sexually transmitted diseases (STDs).

To prevent re-infection with trichomoniasis, make sure any partner is treated too. It is best to avoid having sex for seven days after your or your partner’s treatment to lower the chance of you both getting the infection again.

If you are sexually active, you can do the following things to lower your chances of getting trichomoniasis:

• Be in a long-term mutually monogamous relationship with a partner who has been tested and has negative STD test results;
• Use latex condoms the right way every time you have sex. This can lower your chances of getting trichomoniasis. But the parasite can infect areas that are not covered by a condom – so condoms may not fully protect you from getting trichomoniasis.

Another approach is to talk about the potential risk of STDs before you have sex with a new partner. That way you can make informed choices about the level of risk you are comfortable taking with your sex life.

If you or someone you know has questions about trichomoniasis or any other STD, talk to a health care provider.

Trichomoniasis diagnosis

Your doctor is likely to take a sample from inside the vagina to test for trichomoniasis. Men can be checked with a urine test or a swab from the opening of the penis.

If the Trichomonas vaginalis parasite can be seen under the microscope, no further tests are needed.

If the test doesn’t show the parasite, but your doctor thinks you may have trichomoniasis, other tests may be done. Your doctor may order tests done on a sample of vaginal fluid, a penis uretheral swab or sometimes urine. Tests include a rapid antigen test and nucleic acid amplification test (NAAT).

If you have trichomoniasis, your doctor may also want to test you for other sexually transmitted infections (STIs) so they can also be treated.

Trichomoniasis test

In clinical practice, wet mount preparation has been the most commonly used method for diagnosing trichomoniasis, primarily because of the low cost, convenience, and point-of-care diagnosis ²⁴, ²⁵. The wet mount preparation however has a sensitivity (44 to 68%) that is significantly lower than with newer molecular nucleic acid amplification tests (NAATs) ²⁶. Papanicolaou (PAP) testing is not considered an appropriate diagnostic tool for trichomoniasis; if Trichomonas vaginalis infection is identified on routine Papanicolaou (PAP) testing, a standard trichomonas diagnostic test should be used to verify infection ²⁷. The following summarizes the major methods used to diagnose trichomoniasis.

Wet Mount Preparation

The traditional diagnostic method for trichomoniasis has been wet mount with microscopic visualization of motile Trichomonas vaginalis parasites on slide preparations from vaginal or urethral secretions. Ideally, specimens should be examined within 10 minutes to observe motile parasites, which are diagnostic. Wet mount is an inexpensive diagnostic test; however, sensitivity is estimated at 51-65%, and varies based on the individual performing the test and how promptly the slide is interpreted ²⁸.

Figure 3. Trichomonas vaginalis on Wet Mount preparation

Footnote: This photomicrograph taken of a vaginal discharge wet mount sample shows numerous oval Trichomonas vaginalis protozoan parasites; the black arrow on left indicates two characteristic Trichomonas vaginalis organisms (the thin flagellum can be faintly seen).

[Source ²⁹ ]

Culture

Obtaining a culture using modified Diamond’s medium was the previous gold standard for diagnosis of trichomoniasis prior to the availability of highly sensitive NAATs. Culture has been considered the gold standard for diagnosis of trichomoniasis with a specificity approaching 100%, but it is not widely used and its sensitivity can be as low as 75–96% ²⁸. Culture is a more sensitive diagnostic tool than wet mount alone, but results are not immediately available. Clinical specimens can be inoculated into transport systems such as Amies gel medium to maintain viability for up to 24 hours at room temperature ³⁰. Specialized culture systems (i.e. InPouch System [Biomed Diagnostics]) are available to allow for transport of cultures when shipping to an off-site laboratory. Additionally, these systems can be used to transport specimens after inoculation. Such systems are useful when immediate transportation of specimens to the laboratory is not available. The specimen should be inoculated as soon as possible (within an hour of collection) to maintain viability of the organism.

Culture may be used for diagnosing Trichomonas vaginalis in both men and women. Culture in men may be performed on samples of urethral secretions, urine sediment, or semen, but testing in women requires sampling of vaginal secretions, as the sensitivity is low in urine culture ³¹. Trichomonas vaginalis culture is categorized by the Clinical Laboratory Improvement Amendments (CLIA) as moderately complex as it is time-consuming and requires incubation ²⁶. If Trichomonas vaginalis is isolated in culture, drug susceptibility testing can be performed, particularly in cases of persistent infection.

Nucleic Acid Amplification Testing (NAAT)

Several NAAT-based methods are available for diagnosis of Trichomonas vaginalis, including transcription-mediated amplification and polymerase chain reaction (PCR). There are no data to suggest Trichomonas vaginalis causes anorectal infection, and therefore use of NAAT to detect Trichomonas vaginalis anorectal infection is not recommended ³¹, ³², ³³.

• Aptima Trichomonas vaginalis Assay (Becton Dickinson): This assay uses transcription-mediated amplification for detection of Trichomonas vaginalis RNA ⁹. This test is FDA-cleared for detection of Trichomonas vaginalis in symptomatic and asymptomatic women ³⁴. The test can be performed on clinician-collected vaginal swabs, clinician-collected endocervical swabs, female urine specimens, or liquid endocervical Pap smear specimens collected in PreservCyt Solution ³⁵. The Aptima Trichomonas vaginalis assay has a sensitivity of 95.3 to 100% and specificity of 95.2 to 100%, which are considerably higher than wet mount or culture ³⁶, ⁹, ³⁷. The Aptima Trichomonas vaginalis assay is not FDA-cleared for use in men, but it may be used to test urine or urethral swabs from men if the assay is internally validated in accordance with CLIA regulations ³⁴.
• Probe Tec TV Qx Amplified DNA Assay (Becton-Dickinson): This assay uses Strand Displacement Amplification technology and is FDA-cleared for detection of Trichomonas vaginalis from vaginal swabs (clinician-collected or self-collected), endocervical swabs (clinician-collected), and female urine specimens ³⁴. This assay can be used to detect Trichomonas vaginalis in symptomatic and asymptomatic females. The Probe Tec TV Qx Amplified DNA assay has a sensitivity of 98.3% and specificity of 99.6% for detecting Trichomonas vaginalis ³⁸.
• GeneXpert TV (Cepheid): This PCR-based NAAT is FDA-cleared for detection of Trichomonas vaginalis genomic DNA using self-collected or clinician-collected vaginal specimens, female urine specimens, clinician-collected endocervical swab specimens, and male urine specimens ³⁴, ³⁹. With this assay, the results are available within 63 minutes; for samples that have a clear positive result after 45 PCR cycles have been completed, the Early Assay Termination function will provide the positive result earlier, typically within 40 minutes ³⁹. The GeneXpert TV has a sensitivity of 99.5 to 100% and a specificity of 99.4 to 99.9% ⁴⁰.
• Max CTGCTV2 Assay (Becton Dickinson): This FDA-cleared PCR assay for gonorrhea and chlamydia has been modified to test concurrently for Trichomonas vaginalis ⁴¹. This test is FDA-cleared for detection of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis from vaginal specimens (self-collected or clinician-collected), female urine specimens, and male urine specimens ³⁴. The Max CTGCTV2 Assay has a sensitivity of 96.2 to 100% and specificity of 99.1 to 100% for detecting Trichomonas vaginalis ⁴⁰.
• Cobas TV/MG (Roche Diagnostics): This PCR-based NAAT is FDA-cleared for detection of Trichomonas vaginalis and M. genitalium using vaginal specimens (self-collected or clinician-collected), clinician-collected endocervical swab specimens, female urine specimens, male urine specimens, and clinician-collected meatal specimens ⁴². This assay is FDA-cleared for both symptomatic and asymptomatic patients. The Cobas TV/MG has a sensitivity and specificity greater than 99.5% ⁴², ⁴³.

Point-of-Care Testing

There are multiple point-of-care tests available for diagnosing trichomoniasis in women ⁴⁴:

• Osom Trichomonas Rapid Test (Sekisui Diagnostics): This is an antigen-detection point-of-care test for use with clinician-collected vaginal samples. The test requires about 10 to 15 minutes for test results to become available; this test has a sensitivity of 82 to 95% and a specificity of 97 to 100% ⁴⁵. The Osom Trichomonas Rapid Test is not FDA-cleared for use in men.
• Solana Trichomonas Assay (Quidel): This point-of-care test uses isothermal Helicase-Dependent Amplification technology to detect Trichomonas vaginalis DNA from asymptomatic and symptomatic female urine specimens or clinician-collected vaginal specimens, with a sensitivity greater than 92% for urine specimens and greater than 98% for vaginal samples ⁴⁶. Results are available within 40 minutes. This test is not FDA-cleared for use in men.
• Sexual Health Click Test (Visby Medical): This point-of-care PCR test is a single-use, disposable test that can detect chlamydia, gonorrhea, and trichomonas using self-collected vaginal swabs ⁴⁷. The compact test device provides results within 30 minutes. In an analysis of self-collected vaginal swabs obtained in 1,449 women, this test had a sensitivity of 99.2% and specificity of 96.9% for detection of Trichomonas vaginalis ⁴⁷. This assay received FDA clearance and a CLIA waiver in August 2021.

Trichomoniasis treatment

Trichomoniasis can be treated with oral antibiotic (either metronidazole or tinidazole or secnidazole). These pills are taken by mouth. It is safe for pregnant women to take this medication. Don’t drink alcohol for 24 hours after taking metronidazole, 48 hours after taking secnidazole or 72 hours after taking tinidazole. Drinking alcohol during and for a few days after treatment can cause severe nausea and vomiting.

Oral antibiotic options may include:

• Megadose. Your doctor may recommend one large dose (megadose) of either metronidazole (Flagyl), tinidazole (Tindamax) or secnidazole (Solosec). You only take these oral medications one time.
• Multiple doses. Your provider might recommend several lower doses of metronidazole or tinidazole. You take the pills two times a day for seven days. To help clear up the infection completely, keep taking this medicine for the full time your provider prescribed the drug, even if you begin to feel better after a few days. If you stop using this medicine too soon, your infection may not go away completely.

Recommended oral antibiotic regimen for Women ³⁴:

• Metronidazole 500 mg orally twice a day for 7 days

Recommended oral antibiotic regimen for Men ³⁴:

• Metronidazole 2 g orally in a single dose

Alternative oral antibiotic regimen for Women and Men ³⁴:

• Tinidazole2 g orally in a single dose

People who have been treated for trichomoniasis can get it again. About 1 in 5 people get infected again within 3 months after receiving treatment. To avoid getting reinfected, make sure that all of your sex partners get treated. Also, wait 7- 10 days after you and your partner have been treated to have sex again. This usually takes about a week after finishing the last antibiotic dose.  Get checked again if your symptoms come back.

Your doctor will typically retest you for trichomoniasis after treatment. A retest two weeks to three months after treatment can check to be sure the infection is gone and that you haven’t been reinfected.

Even if you’ve had treatment that gets rid of trichomoniasis, it’s possible to get it again if you’re exposed to someone with the infection.

Trichomoniasis cure

Recommended oral antibiotic regimen for Women ³⁴:

• Metronidazole 500 mg orally twice a day for 7 days

Recommended oral antibiotic regimen for Men ³⁴:

• Metronidazole 2 g orally in a single dose

Alternative oral antibiotic regimen for Women and Men ³⁴:

• Tinidazole2 g orally in a single dose

The nitroimidazoles are the only class of antimicrobial medications known to be effective against Trichomonas vaginalis infections. Of these drugs, metronidazole and tinidazole have been cleared by FDA for the oral or parenteral treatment of trichomoniasis ⁴⁸. Tinidazole is generally more expensive, reaches higher levels in serum and the genitourinary tract, has a longer half-life than metronidazole (12.5 hours versus 7.3 hours), and has fewer gastrointestinal side effects ⁴⁹. In randomized clinical trials, recommended metronidazole regimens have resulted in cure rates of approximately 84%–98% ⁴⁹, and the recommended tinidazole regimen has resulted in cure rates of approximately 92%–100% ⁵⁰. Randomized controlled trials comparing single 2 g doses of metronidazole and tinidazole suggest that tinidazole is equivalent or superior to metronidazole in achieving parasitologic cure and resolution of symptoms ⁵¹.

Metronidazole gel does not reach therapeutic levels in the urethra and perivaginal glands. Because it is less efficacious than oral metronidazole, it is not recommended.

Treatment of persistent or recurrent trichomoniasis

The most likely reasons for persistent or recurrent trichomoniasis are reinfection from an untreated partner or lack of adherence with treatment, but in some individuals, antimicrobial-resistant Trichomonas vaginalis infection can occur. Currently, rates of metronidazole resistance range from 4 to 10%, and the rate of tinidazole resistance is about 1% ⁵², ⁵³. Tinidazole retains activity against many metronidazole-refractory strains. The following summarizes the approach to treatment in persons with persistent or recurrent trichomoniasis ³⁴.

• Treatment Failure with Reexposure: For women and men who received standard treatment for trichomoniasis and have treatment failure due to reexposure from an untreated partner, retreatment should consist of the same regimen they initially received ³⁴.
• Treatment Failure without Reexposure: For men who have treatment failure after receiving an initial single-dose therapy of metronidazole 2 grams orally (and reexposure has not occurred), the recommended retreatment is metronidazole 500 mg orally twice daily for 7 days ³⁴. For women who have failed the initial regimen of metronidazole 500 mg twice daily for 7 days and have not been reexposed, repeat treatment should be given with a 7-day regimen of either metronidazole 2 grams given once per day or tinidazole 2 grams once per day ³⁴. Tinidazole should not be used in pregnant women.
• Treatment Failure after Second-Line Treatment without Reexposure: If an individual experiences persistent infection after receiving treatment with a second-line regimen (and reexposure to a partner with trichomoniasis has not occurred), the clinician should request a special kit from the Centers for Disease Control and Prevention for 5-nitroimidazole drug-resistance testing (Trichomonas Susceptibility Testing) ³⁴.
• Treatment of 5-Nitroimidazole-Resistant Trichomonas: If drug-resistance testing reveals nitroimidazole resistance and treatment with a 7-day regimen of either metronidazole 2 grams given once per day or tinidazole 2 grams once per day has been unsuccessful, then the next option is oral tinidazole 2 grams daily plus intravaginal tinidazole 500 mg twice daily for 14 days ³⁴. If this option fails, then consider using high-dose oral tinidazole (1 gram 3 times daily) plus intravaginal paromomycin (4 grams of 6.25% intravaginal paromomycin cream nightly) for 14 days ³⁴. Note that tinidazole should not be used in pregnant women. Intravaginal boric acid has been used to treat trichomoniasis in women allergic to nitroimidazole and thus could be considered as an option for women with treatment-refractory nitroimidazole-resistant trichomoniasis ³⁴.

Other Management Considerations

You should abstain from sex until you and your sex partners are treated and until you and your partners no longer have any symptoms of trichomoniasis. This usually takes about 7 days after completion of treatment ³⁴.

Testing for other STDs including HIV should be performed in people infected with Trichomonas vaginalis.

Follow-up

Because of the high rate of reinfection among women treated for trichomoniasis (17% within 3 months in one study) ⁵⁴, retesting for T. vaginalis is recommended for all sexually active women within 3 months following initial treatment regardless of whether they believe their sex partners were treated. Testing by nucleic acid amplification can be conducted as soon as 2 weeks after treatment ⁵⁵. Data are insufficient to support retesting men ³⁴.

Management of Sex Partners

Concurrent treatment of all sex partners is critical for symptomatic relief, microbiologic cure, and prevention of transmission and reinfections. Current partners should be referred for presumptive therapy to avoid reinfection. Partners should be advised to abstain from intercourse until they and their sex partners have been adequately treated and any symptoms have resolved. EPT might have a role in partner management for trichomoniasis ⁵⁶ and can be used in states where permissible by law; however, no one partner management intervention has been shown to be superior in reducing reinfection rates. Though no definitive data exist to guide treatment for partners of persons with persistent or recurrent trichomoniasis in whom nonadherance and reinfection are unlikely, partners benefit from undergoing evaluation and receiving the same regimen as the patient (see Persistent or Recurrent Trichomoniasis).

Treatment of women during pregnancy

Trichomonas vaginalis infection in pregnant women is associated with adverse pregnancy outcomes, particularly premature rupture of membranes, preterm delivery, and delivery of a low birthweight infant ⁵⁷. Pregnant women with symptomatic trichomoniasis, in any trimester, should receive treatment with metronidazole 500 mg orally twice daily for 7 days ³⁴. Treatment of asymptomatic trichomoniasis in pregnancy, however, has not been shown to reduce preterm birth ⁵⁸. One trial suggested the possibility of increased preterm delivery in women with Trichomonas vaginalis infection who received metronidazole treatment ⁵⁸, yet study limitations prevented definitive conclusions regarding the risks of treatment. More recent, larger studies have shown no positive or negative association between metronidazole use during pregnancy and adverse outcomes of pregnancy ⁵⁹. Symptomatic pregnant women, regardless of pregnancy stage, should be tested and considered for treatment. Treatment of Trichomonas vaginalis infection can relieve symptoms of vaginal discharge in pregnant women and reduce sexual transmission to partners. Although perinatal transmission of trichomoniasis is uncommon, treatment also might prevent respiratory or genital infection of the newborn ⁶⁰. Clinicians should counsel symptomatic pregnant women with trichomoniasis regarding the potential risks for and benefits of treatment and about the importance of partner treatment and condom use in the prevention of sexual transmission.

Although metronidazole crosses the placenta, data suggest that it poses a low risk to pregnant women ⁶¹. No evidence of teratogenicity or mutagenic effects in infants has been found in multiple cross-sectional and cohort studies of pregnant women ⁶².

Both metronidazole and tinidazole are secreted in breast milk (https://www.ncbi.nlm.nih.gov/books/NBK501922). Metronidazole is secreted in breast milk. With maternal oral therapy, breastfed infants receive metronidazole in doses that are lower than those used to treat infections in infants, although the active metabolite adds to the total infant exposure. Plasma levels of the drug and metabolite are measurable, but remain less than maternal plasma levels. Although several reported case series found no evidence of adverse effects in infants exposed to metronidazole in breast milk, some clinicians advise deferring breastfeeding for 12–24 hours after taking a dose of metronidazole ³⁴, ⁶³. Tinidazole is not recommended during pregnancy due to limited animal studies suggesting fetal risk; women who are breastfeeding should wait 72 hours after taking tinidazole before breastfeeding ³⁴.

Treatment of women with HIV

Up to 53% of women with HIV infection also are infected with Trichomonas vaginalis ⁶⁴. Trichomonas vaginalis infection in these women is significantly associated with pelvic inflammatory disease ⁶⁵, and treatment of trichomoniasis is associated with significant decreases in genital-tract HIV viral load and viral shedding ⁶⁶. For these reasons, routine screening and prompt treatment are recommended for all women with HIV infection; screening should occur at entry to care and then at least annually thereafter. A randomized clinical trial involving women with HIV infection and Trichomonas vaginalis infection demonstrated that a single dose of metronidazole 2 g orally was less effective than 500 mg twice daily for 7 days ⁶⁷. Thus, to improve cure rates, women with HIV infection who receive a diagnosis of Trichomonas vaginalis infection should be treated with a 7-day treatment course of metronidazole 500 mg twice daily (rather than with a 2-g single dose of metronidazole) ³⁴. This longer course of therapy has been shown to have higher cure rates than single-dose metronidazole therapy in women with HIV ¹⁸, ⁶⁸, ⁶⁹.

Factors that might interfere with standard single-dose treatment for trichomoniasis in these women include high rates of asymptomatic bacterial vaginosis co-infections, use of antiretroviral therapy, changes in vaginal ecology, and impaired immunity ⁷⁰.

In women with HIV infection who receive a diagnosis of T. vaginalis infection, retesting is recommended within 3 months following initial treatment; NAAT is encouraged because of higher sensitivity of these tests. Data are insufficient to recommend routine screening, alternative treatment regimens of longer duration, or retesting in men.

Pregnant women with HIV who are treated for Trichomonas vaginalis infection should be retested 3 months after treatment.

Allergy, Intolerance, and Adverse Reactions

Metronidazole and tinidazole are both nitroimidazoles. Patients with an IgE mediated-type allergy to a nitroimidazole can be managed by metronidazole desensitization according to a published regimen ⁷¹ and in consultation with a specialist.

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