When it comes to sexually transmitted infections (STIs), most people immediately think of chlamydia, gonorrhea, or HIV. But there’s another extremely common, and often overlooked, parasite that affects millions worldwide: Trichomoniasis. Caused by Trichomonas vaginalis, this parasitic STI can lead to many problems, yet many people don’t even know they have it.

What makes trichomoniasis particularly tricky is that its symptoms can easily be mistaken for other infections like bacterial vaginosis, or in many cases, may not appear at all. Without proper diagnosis and treatment, it can increase the risk of serious reproductive health issues and the transmission of other STIs, including HIV.

In this blog, we’ll break down everything you need to know about trichomoniasis—from how it spreads and what symptoms to look for, to the best testing options, and treatments.

What Is Trichomoniasis?

Trichomoniasis is a sexually transmitted infection (STI) caused by the parasitic protozoan Trichomonas vaginalis. It’s one of the most common non-viral STIs worldwide, infecting approximately 156 million people aged 15–49 each year. While it often affects adults, it can also impact newborns and increase vulnerability to other infections.

The Parasite: Trichomonas vaginalis

The culprit behind this condition is Trichomonas vaginalis, a single-celled, flagellated protozoan. Thriving in moist environments such as the genitals and urethra, this parasite feeds on epithelial cells and body fluids.

How Do You Get the Infection?

Transmission occurs almost exclusively through sexual contact; vaginal intercourse is the most common route. You can also get infected via genital-to-genital touch and, more rarely, through oral or anal contact. Pregnant women can pass the infection to their babies during childbirth, potentially leading to neonatal complications.

Trichomoniasis Symptoms:

How long after exposure do symptoms appear?

Symptoms typically start 5–28 days post-infection

What to Watch For

  1. Genital Itching / Irritation
    A primary sign—especially among women—is persistent genital itching, burning, and irritation around the vulva or penile area. This discomfort often worsens with urination and intercourse.
  2. Frothy, FoulSmelling Discharge
    In women, the infection typically causes a yellow-green, frothy, foul-smelling discharge—often described as fishy. This is a hallmark symptom of trichomoniasis.
  3. Burning During Urination
    Pain or burning sensation during urination is common in both sexes. Although sometimes confused with urinary tract infections, discomfort during urination in sexually active individuals should raise suspicion of trichomoniasis.
  4. Men May Not Notice
    Up to 70–85% of male carriers show no symptoms, though some may experience mild urethral irritation or penile discharge. Even without symptoms, men can transmit the parasite to partners.
  5. Incubation Period
    Symptoms typically emerge 5–28 days after exposure, with most cases appearing around the second week.

Why Is Trichomoniasis Often Underdiagnosed?

Many cases go unnoticed for several reasons:

  • High rate of asymptomatic cases: about 80% of infections show no signs.
  • Low sensitivity of basic tests: wet-mount microscopy—while quick—is only about 50–70% accurate.
  • Limited testing protocols: Routine screening isn’t standard for all patient groups.

These factors result in missed diagnoses, ongoing transmission, and untreated health risks.

Tests for Trichomoniasis:

What’s the best test for trichomoniasis?

NAAT is the most accurate and reliable. For quick results, antigen tests are effective.

NAAT (Nucleic Acid Amplification Test)

  • The current gold standard—detects T. vaginalis DNA or RNA.
  • Can be done using urine or swab samples.
  • Sensitivity and specificity are excellent, often >95%.

Wet Mount Test (Microscopy)

  • A genital fluid sample (vaginal or urethral) is placed on a slide with saline and examined under a microscope.
  • Live, motile parasites confirm the infection—but sensitivity drops sharply if not examined immediately.
  • Sensitivity ranges from 44–68%.

Antigen Detection Test

  • Rapidly identifies parasite proteins using an immunochromatographic dipstick.
  • Results are available in 10–15 minutes.
  • Sensitivity is higher than wet mount (82–95%), though slightly lower than NAAT.

Culture Test

  • Involves growing the parasite in specialized media.
  • Takes up to 7 days: sensitivity ranges from 44–75%.
  • Now mainly used for confirmatory testing or in research.

AtHome Test Kits

Home testing kits make diagnosis easier:

  • Include a urine collection cup (for both sexes) or vaginal swab (for women).
  • Follow clear instructions, then mail the sample to a lab.
  • Results are typically returned in a few days—convenient for discreet and early testing.

Trichomoniasis Treatment & Cure

Is the infection curable?

Yes—prompt antibiotic treatment plus partner treatment is essential. Metronidazole is highly effective.

Metronidazole or Tinidazole

A single dose of metronidazole or tinidazole under close medical supervision is the standard treatment, curing over 95% of infections. In cases of treatment failure, a 7-day metronidazole course is recommended, particularly in HIV-positive individuals.

Partner Treatment

To prevent reinfection, all sexual partners should be treated, even if symptomless. Abstain from sex until at least 7 days after treatment completion.

Reinfection Risk:

Can men get reinfections?

Yes—men can be reinfected if they resume sex with untreated partners.

Reinfection occurs in about 20% of individuals within three months, highlighting the need for follow-up testing and safer sex practices.

Complications of Untreated Infection

If left untreated, trichomoniasis can cause:

  • Pelvic inflammatory disease (PID) and increased risk of infertility in women
  • Preterm birth and low birth weight infants 
  • Increased risk of acquiring or transmitting HIV 
  • In men, accessory gland infections like prostatitis and epididymitis, possibly affecting fertility 
  • Chronic inflammation in the genital tract

Prevention Strategies

Condom Use

Consistent use of male or female condoms significantly reduces trichomoniasis transmission.

Safe Sexual Practices

Limiting partners, mutual monogamy, and regular STI screening protect against reinfection and partner spread.

Routine Screening

Women with symptoms of vaginitis and individuals at high risk (e.g., multiple partners, history of STIs, HIV-positive) should receive regular screening.

Trichomoniasis vs. Bacterial Vaginosis: What’s the Difference?

AspectTrichomoniasisBacterial Vaginosis (BV)
CauseParasitic infection caused by Trichomonas vaginalisBacterial imbalance, often overgrowth of Gardnerella vaginalis
Type of InfectionSexually transmitted infection (STI)Not classified as an STI (but more common in sexually active women)
TransmissionSpread through vaginal, oral, or anal sexNot spread through sexual contact but linked to sexual activity
SymptomsGenital itching, frothy yellow-green discharge, foul odor, burning urinationThin gray/white discharge, strong fishy odor, mild or no irritation
Common inBoth men and women (more symptoms in women)Primarily affects women
Asymptomatic CasesVery common, especially in menAlso common, especially in mild cases
Testing MethodsNAAT, Wet Mount, Antigen Detection, CultureVaginal swab, pH test, clue cell microscopy, amine test
Itching/IrritationCommonRare
Burning During UrinationFrequently reportedOccasionally
Pain During IntercourseSometimesRarely
Risk If UntreatedInfertility, PID, increased HIV risk, pregnancy complicationsIncreased STI risk, preterm birth, and miscarriage
Partner Treatment Needed?Yes, to prevent reinfectionNo, usually not required
Can You Have Both?Yes, co-infection is commonYes, often occurs with trichomoniasis or other STIs

Conclusion

Trichomoniasis is a silent yet widespread public health issue that demands attention. Despite often mild or absent symptoms, genital itching, frothy discharge, and burning urination are red flags. With advanced diagnostic tools like NAAT and rapid antigen tests, we can detect and treat infections early, especially important given the rising asymptomatic cases.

Treatment is simple and effective with metronidazole but requires treating all sexual partners and abstaining until fully cured. Prevention through condom use, regular screening, and honest partner communication remains critical.

By enhancing awareness and adopting regular testing habits, we can better control this common yet underdiagnosed STI. If you’re experiencing symptoms or have had new or multiple partners, don’t wait get tested, treated, and protect your sexual health.

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Written By
Dr. Rahaf Wagdy

Medical Content Writer

Dr. Rahaf Wagdy is an Egyptian nuclear radiologist and medical content creator who merges her clinical expertise with digital creativity. With over five years of experience in medical content writing in both Arabic and English, she is dedicated to simplifying...

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