Yes, trichomoniasis is a sexually transmitted disease (STD), and it is actually the most common curable one in the world. An estimated 2.6 million people in the United States are infected at any given time. It’s caused by a microscopic parasite called Trichomonas vaginalis that passes between partners during sex.
How Trichomoniasis Spreads
The parasite spreads during vaginal sex, moving from a penis to a vagina, from a vagina to a penis, or from one vagina to another. It does not commonly infect the hands, mouth, or anus, which makes it different from STDs like herpes or gonorrhea that can affect multiple body sites.
While sexual contact is overwhelmingly the primary route, non-sexual transmission has been documented in rare cases. A study in Zambia found a surprisingly high rate of trichomoniasis among adolescent girls who had never had sex, traced to shared bathing water. Separate case reports have identified transmission through shared bath towels. These situations are uncommon, but they explain how someone with no sexual history could occasionally test positive.
Many Infections Have No Symptoms
Trichomoniasis is easy to miss because a large portion of infected people never develop noticeable symptoms. Only about 30% of those carrying the parasite experience any signs at all. When symptoms do appear, they tend to show up within 5 to 28 days of exposure, though some people develop them much later.
In women, the most recognizable symptom is an unusual vaginal discharge that may be yellow-green, frothy, or foul-smelling. Itching, burning, or redness around the genitals is common, along with discomfort during urination or sex. In men, symptoms are even less likely to appear, but can include irritation inside the penis, a mild discharge, or a burning sensation after urination or ejaculation.
Because most infections are silent, you can carry and transmit the parasite without knowing it. This is a major reason trichomoniasis remains so widespread.
Who Is Most Affected
Trichomoniasis affects women more often than men. Population-level data from the U.S. shows a prevalence of 2.1% among women compared to 0.5% among men. The rates are not evenly distributed across demographics: Black women have a prevalence of 9.6% and Black men 3.6%, compared to 0.8% among non-Hispanic white women and 1.4% among Hispanic women. These disparities reflect differences in access to screening and treatment, not differences in sexual behavior.
Why It Matters Beyond Discomfort
Trichomoniasis is often dismissed as a minor infection, but untreated cases carry real health risks. The parasite causes inflammation in the genital tract, which makes it easier to acquire or transmit HIV. The irritated tissue essentially creates an easier entry point for the virus.
During pregnancy, the stakes are higher. Trichomoniasis has been linked to preterm labor, premature rupture of membranes, low birth weight, and post-delivery infections. These complications make screening and treatment during pregnancy particularly important.
How It’s Diagnosed
The traditional test for trichomoniasis is a wet mount, where a sample of vaginal fluid is examined under a microscope for moving parasites. It’s fast and cheap, but it catches only 36% to 75% of infections, even when performed by experienced lab professionals. That means it misses a significant number of cases.
Molecular tests, known as nucleic acid amplification tests (NAATs), are far more accurate, with sensitivities above 90% and often approaching 100%. These tests can detect the parasite’s genetic material even when the organism count is too low for a microscope to pick up. NAATs can detect three to five times more infections than wet mount microscopy. If you’re being tested, it’s worth knowing which method your provider is using, since a negative wet mount doesn’t reliably rule out infection.
Treatment and Follow-Up
Trichomoniasis is curable with prescription antibiotics, typically taken by mouth. Treatment is straightforward, but a few details matter for making sure the infection actually clears.
Your sexual partner needs to be treated at the same time, even if they have no symptoms. Having sex before both partners finish treatment, particularly without a condom, is a common reason infections bounce back. Reinfection from an untreated partner is one of the biggest challenges in controlling trichomoniasis.
After completing treatment, you should get retested to confirm the parasite is gone. The timing of that retest matters: three weeks after finishing treatment if you took a multi-day course, or four weeks if you took a single-dose treatment. Testing too early can produce a false negative because remnants of dead parasite DNA may still be clearing from your body.
How to Reduce Your Risk
Condoms significantly lower the chance of transmission but don’t eliminate it entirely, since the parasite can infect areas of skin not covered by a condom. Limiting the number of sexual partners reduces your overall exposure risk. Because trichomoniasis so often has no symptoms, regular STD screening is the most reliable way to catch an infection early, especially if you have a new partner or multiple partners. If you test positive, getting your partner treated before resuming sexual contact is the single most effective step to prevent reinfection.