Trichomoniasis: comprehensive clinical features, diagnosis, treatment and partner management

1. Learning objectives

By the end of this topic, a student should be able to:

• Identify the causative organism, its important biological features and routes of transmission.
• Describe presentation in women and men, including asymptomatic infection and pregnancy considerations.
• Take a sensitive history and identify signs requiring urgent assessment for PID or another diagnosis.
• Select and interpret wet mount microscopy, NAAT, culture and supportive bedside findings.
• Differentiate trichomoniasis from bacterial vaginosis, candidiasis and gonorrhoea/chlamydia cervicitis.
• Outline treatment, partner management, prevention, follow-up and a safe approach to persistent symptoms.

2. Causative organism and epidemiology

T. vaginalis is a flagellated protozoan parasite that inhabits the human urogenital tract. It is usually described in its motile trophozoite form and does not have a durable cyst stage. On a fresh wet preparation, trophozoites may be recognised by their motility; they rapidly lose motility after collection, which is why prompt microscopy matters.

Trichomoniasis is one of the most common non-viral STIs worldwide. WHO estimated approximately 156 million new infections among people aged 15–49 years in 2020; a substantial share occurred in the WHO African Region. These are modelled global estimates, not a current prevalence estimate for Uganda or an individual district. Infection may persist for months or longer without treatment, and absence of symptoms does not mean a person is uninfected.

Both women and men can acquire and transmit infection. Symptoms are more often recognised in women, while men are frequently asymptomatic. An infected person may transmit infection before diagnosis.

3. Transmission and risk factors

Transmission is primarily through sexual contact involving infected genital secretions, especially penile–vaginal sex. Transmission between women who have sex with women can occur through transfer of vaginal fluids or contaminated sexual devices. It is not acquired from ordinary casual contact such as sharing a classroom, toilet seat or handshake.

Risk is higher with a current partner who has an STI, new or multiple partners, inconsistent condom use, a previous STI, and limited access to testing or partner treatment. These factors guide a non-judgemental history and testing discussion; they do not prove infection. Avoid stigmatising language or assumptions about behaviour.

4. Pathophysiology

The organism adheres to urogenital epithelium and provokes local inflammation. In the vagina this can disrupt epithelial cells and recruit inflammatory cells, producing irritation, erythema and discharge. Vaginal pH is often above 4.5, but this is not specific: bacterial vaginosis can also raise pH. In men, infection may involve the urethra and cause urethritis, although many infections are clinically silent.

Inflammation can increase genital mucosal vulnerability and is associated with increased HIV acquisition and transmission risk. The association is important in sexual-health care, but it does not mean HIV transmission will necessarily occur. Offer HIV testing and prevention services according to consent and local protocol.

5. Clinical features

5.1 Women

Presentation ranges from no symptoms to bothersome vulvovaginitis or cervicitis. Possible symptoms and signs include:

• Vaginal discharge that may be diffuse, malodorous, purulent, yellow-green or occasionally frothy.
• Vulval or vaginal itching, soreness, burning, redness or irritation.
• Dysuria, urinary frequency, discomfort during intercourse or lower abdominal discomfort.
• Vaginal inflammation and, less commonly, a punctate or “strawberry” appearance of the cervix. This is classically taught but not always visible on routine examination.
• No obvious symptoms, despite infection and potential transmission.

5.2 Men

Most infected men have no recognised symptoms. When present, symptoms may include urethral irritation, dysuria, penile itching or scant urethral discharge. Urethritis is a more practical clinical description than assuming every patient will have visible discharge. Epididymal or prostatic symptoms have been reported but require assessment for other causes as well.

5.3 Symptoms requiring a broader assessment

Fever, significant pelvic or lower abdominal pain, cervical motion tenderness, adnexal tenderness, pregnancy with pain or bleeding, genital ulcers, testicular pain or systemic illness should not be attributed to uncomplicated trichomoniasis without further assessment. Consider PID, ectopic pregnancy, urinary infection, epididymo-orchitis, genital herpes or another urgent condition and refer/escalate as indicated.

6. Complications and special populations

Trichomoniasis is associated with adverse pregnancy outcomes, including premature rupture of membranes, preterm delivery and low birth weight or small-for-gestational-age infants. This is an association and does not prove that infection alone caused an outcome in an individual pregnancy. Symptomatic pregnant patients should receive clinical assessment and treatment according to current guidance. Routine screening of every asymptomatic pregnant patient is not established in all guidelines; follow national policy and individual risk.

Infection is associated with increased HIV acquisition risk. Among women living with HIV, trichomoniasis has also been associated with PID. The infection may coexist with bacterial vaginosis or other STIs, so a positive result should prompt an appropriate broader sexual-health assessment. Persistent symptoms can cause distress, anxiety or relationship concerns; provide confidential, respectful counselling.

7. History and examination

7.1 Focused history

• Symptoms: onset and duration of discharge, odour, itch, soreness, dysuria, dyspareunia, bleeding after sex, pelvic pain, fever or genital lesions.
• Reproductive context: last menstrual period, possibility of pregnancy, pregnancy or breastfeeding status, contraception and relevant antenatal care.
• Sexual-health context: recent exposure, partner symptoms or diagnosis, condom use, new partners and whether a partner received treatment. Ask privately, with consent, and without blame.
• Clinical context: prior STIs or trichomoniasis, recent antibiotics or nitroimidazoles, medication allergies, HIV status/testing preferences and relevant co-morbidities.
• Safety: ask whether contact was consensual when clinically appropriate; follow safeguarding and sexual-violence protocols if abuse or coercion is disclosed.

7.2 Examination

Explain each step, obtain consent and offer a chaperone according to local practice. Examine the abdomen if pain is present. If indicated and acceptable to the patient, inspect the external genitalia, vaginal walls and cervix for erythema, discharge, lesions, bleeding or a foreign body; perform a bimanual examination when pelvic pain or PID is suspected. For men with symptoms, inspect the urethral meatus and discharge and assess the testes/epididymides if pain or swelling is reported. A normal-looking examination does not exclude infection.

8. Investigations and interpretation

Choose a test that is available, acceptable and validated for the specimen and patient population. Follow the laboratory’s collection instructions; a vaginal swab is often preferred for women, while the validated specimen for men depends on the assay and local laboratory. A normal examination or absence of symptoms should not replace testing when testing is indicated.

Important interpretation: a Pap smear is not a diagnostic test for trichomoniasis. If it incidentally reports possible T. vaginalis, confirm with a sensitive test and treat if infection is confirmed. A negative wet mount should be followed by NAAT or another suitable test when clinical suspicion remains and testing is available.

Where reliable laboratory diagnosis is not available, national syndromic management protocols may be used for symptomatic vaginal discharge. Explain that syndromic treatment is designed for settings with limited testing and may treat more than one likely cause; it is not microbiological confirmation. Reassess if symptoms persist.

9. Differential diagnosis of vaginal discharge

10. Treatment principles

Treat confirmed infection and manage symptomatic patients according to current national guidance. Effective medicines are oral nitroimidazoles, principally metronidazole. Intravaginal metronidazole gel alone is not an adequate substitute for systemic treatment of trichomoniasis. Explain the dosing schedule, common adverse effects, the need to complete the course, partner treatment and abstinence during treatment. Do not advise a patient to use another person’s medicine or to self-select a regimen.

Guideline note: treatment recommendations vary by country, population and guideline edition. CDC’s 2021 guidance, for example, uses different recommended regimens for women and men. For practice in Uganda, follow the current UCG/Ministry STI protocol and clinician judgement; the WHO 2024 recommendation above is included for learning and is not for unsupervised self-treatment.

10.1 Practical medicine counselling

• Check allergy history, pregnancy/breastfeeding status, interacting medicines and previous treatment before selecting a regimen.
• Explain that nausea, abdominal discomfort or a metallic taste may occur; advise the patient to contact a clinician for a severe reaction or inability to retain doses.
• Discuss alcohol according to the current Uganda guideline and the medicine’s product information; do not rely on an old slide’s brief dosing note.
• Do not use vaginal douching or topical creams as a substitute for oral treatment of confirmed trichomoniasis.
• If a patient cannot complete or tolerate the regimen, arrange clinical review rather than stopping and restarting medicines without advice.

11. Pregnancy, breastfeeding and HIV

Pregnancy

Assess pregnancy whenever relevant. WHO includes pregnant individuals in its recommendation for metronidazole 400–500 mg orally twice daily for 7 days. CDC notes that metronidazole crosses the placenta but available data indicate low fetal risk; symptomatic pregnant patients should be evaluated and treated. Tinidazole should be avoided during pregnancy in the WHO treatment recommendation because human data are limited and animal data raise concern. Discuss benefits, risks and partner treatment with the patient and follow local antenatal/STI guidance.

Breastfeeding

Ask about breastfeeding and consult current national prescribing guidance or a pharmacist when selecting a regimen, particularly for a single high dose or tinidazole. Do not tell a breastfeeding patient to stop feeding without checking the current recommendation for the specific medicine and dose.

HIV and other STIs

Offer HIV and syphilis testing with informed consent and assess for gonorrhoea and chlamydia as appropriate. Coordinate care with HIV services if the patient is living with HIV. CDC recommends routine trichomoniasis screening at entry to care and at least annually for women with HIV in its US guidance; apply Uganda policy and individual risk rather than importing a screening schedule without context.

12. Partner management and prevention

Current sexual partners should be evaluated and treated promptly according to local STI guidance, even if they have no symptoms. Partner treatment is central to preventing reinfection. Offer confidential partner-notification support and use the pathway available at the health facility. Do not disclose a patient’s diagnosis to a partner without consent except where a specific legal or public-health duty applies.

• Advise the patient and partners to avoid sex until everyone has completed treatment and symptoms have resolved.
• Explain that treatment cures the current infection but does not provide lasting immunity; reinfection can occur.
• Discuss consistent, correct condom use and access to condoms.
• Offer testing for co-infections and prevention services based on the patient’s needs.
• Use neutral language: an infection may have been asymptomatic for a long time, so the result cannot by itself establish when or from whom it was acquired.

13. Follow-up and persistent or recurrent symptoms

Give a clear route back to care if discharge, dysuria, pelvic pain or other symptoms fail to improve or return. For sexually active women, CDC recommends repeat testing at about 3 months because reinfection is common, even if the patient believes partners were treated. Follow national follow-up policy for Uganda; evidence for routine retesting of men is less established in CDC guidance.

When symptoms persist, do not immediately label the organism “drug-resistant.” Work through common explanations first:

1. Check the initial diagnosis: was trichomoniasis confirmed, or was treatment syndromic? Consider NAAT or another appropriate test.
2. Review adherence and tolerability: did the patient complete the course and retain the doses?
3. Assess re-exposure: was a partner untreated, or did sex occur before both parties completed treatment and symptoms resolved?
4. Check repeat-test timing: NAAT performed too soon after treatment may detect residual nucleic acid. CDC advises not using NAAT for recurrent infection before 3 weeks after completion.
5. Consider another diagnosis or co-infection: BV, candidiasis, gonorrhoea, chlamydia, PID, urinary infection or a non-infectious cause.
6. Seek expert guidance for suspected treatment failure: culture and susceptibility advice may be appropriate where available. Do not prescribe prolonged or high-dose regimens without specialist/current guideline input.

14. Worked clinical scenarios

Scenario 1: Vaginal discharge with a negative wet mount

A 23-year-old woman presents to a health centre in Mbarara with four days of malodorous yellow-green discharge and dysuria. She is afebrile and has no lower abdominal pain. A wet mount is negative, but it was examined about 40 minutes after collection.

Reasoning: symptoms are compatible but not diagnostic. A delayed negative wet mount is weak evidence against infection because microscopy sensitivity is low and falls rapidly. Ask about pregnancy and red flags, obtain a vaginal swab/NAAT if available, and test for other STIs according to consent and local policy. If laboratory testing is unavailable, follow the national vaginal-discharge algorithm. Counsel about abstinence and partner assessment rather than assuming candidiasis and giving an isolated antifungal.

Scenario 2: Asymptomatic partner

A patient has a positive NAAT for trichomoniasis. Her current partner says he feels well and asks whether he needs care.

Reasoning: men can be asymptomatic while infected and can reinfect a treated partner. Arrange partner evaluation and presumptive treatment under local STI guidance. Explain confidentiality, avoid blame, and recommend no sex until both have completed treatment and symptoms have resolved.

Scenario 3: Pregnancy and discharge

A pregnant patient reports vaginal irritation and discharge at an antenatal visit. She is stable but worried that treatment will harm the pregnancy.

Reasoning: assess pregnancy context, symptoms and red flags; confirm or manage according to available tests and national protocol. WHO recommends metronidazole 400 or 500 mg twice daily for 7 days for adults/adolescents including pregnant individuals. Explain that symptomatic infection should be reviewed and treated by a clinician; do not substitute tinidazole in pregnancy without appropriate guidance. Include partner treatment and return precautions.

15. Common errors to avoid

• Calling every green discharge trichomoniasis without testing or considering other causes.
• Using a negative or delayed wet mount to rule out infection.
• Relying on a Pap smear as definitive diagnosis.
• Giving intravaginal metronidazole gel alone for confirmed trichomoniasis.
• Leaving current sexual partner(s) untreated, allowing reinfection.
• Advising sex to resume before patient and partner(s) complete treatment and symptoms resolve.
• Using an old SlideShare dose or another country’s regimen instead of the current Uganda protocol.
• Attributing fever, pelvic pain, pregnancy-related pain or testicular pain to uncomplicated trichomoniasis without evaluating urgent alternatives.

16. Exam revision: questions and model answers

17. Key takeaways

• Trichomoniasis is a curable protozoal STI; many infections are asymptomatic.
• Discharge appearance and vaginal pH are clues, not confirmation.
• NAAT is generally the most sensitive test where available; wet mount must be examined promptly and a negative result does not rule out infection.
• Use a current guideline. WHO 2024 suggests metronidazole 400–500 mg orally twice daily for 7 days for adults/adolescents, including pregnant individuals; single-dose options are for serious adherence concerns.
• Evaluate and treat current partners, counsel on abstinence until treatment is complete and symptoms resolve, and offer testing for other STIs.
• Pregnancy, pelvic pain, fever, HIV, persistent symptoms and medication allergy call for individualized clinical review.

18. References and further learning

1. World Health Organization. Recommendations for the treatment of Trichomonas vaginalis, Mycoplasma genitalium, Candida albicans, bacterial vaginosis and human papillomavirus (anogenital warts). Geneva: WHO; 2024.
2. World Health Organization. Trichomoniasis: Fact sheet. Updated 21 November 2025.
3. Centers for Disease Control and Prevention. STI Treatment Guidelines: Trichomoniasis. CDC; last reviewed 2022.
4. Ministry of Health, Uganda. Uganda Clinical Guidelines 2023. Consult current national STI/vaginal-discharge guidance and local facility protocol for clinical practice.
5. Supplemental student revision resource: 03. TRICHOMONIASIS.pptx (SlideShare). Use for a quick review of the organism, clinical picture, investigations and partner prevention. This uploaded slide deck is not a clinical guideline; some dosing and complication statements are dated or not sufficiently qualified, so verify clinical decisions against WHO and Uganda guidance above.

Educational note: This chapter supports study and does not replace clinical assessment, laboratory advice or current Uganda Clinical Guidelines. Medication choice and treatment of pregnant patients, children, people with HIV, drug allergy or persistent infection should be supervised by a qualified health professional.