A diagnosis of Trichomoniasis, often called “trich,” can cause significant confusion and distress, especially for individuals in committed relationships. The discovery of a sexually transmitted infection (STI) often leads to a false assumption of infidelity. This infection is caused by a tiny parasite, and its ability to remain undetected often provides a more complex explanation than recent exposure. Understanding the biology of this common STI and its unique patterns of infection can clarify why a diagnosis might occur in a seemingly monogamous setting.
Understanding the Parasite and Its Prevalence
The infection is caused by a single-celled protozoan parasite named Trichomonas vaginalis. This parasite is one of the most widespread curable STIs globally, affecting millions of people each year. It primarily infects the lower genital tract, including the urethra and the vagina in women, and the urethra and prostate gland in men. While many people experience noticeable symptoms like itching, burning, pain during urination, or an unusual discharge, a large number of infected individuals have no symptoms at all. This lack of signs allows the infection to spread unknowingly, making it a silent presence in the population.
The Asymptomatic Factor: Why Diagnosis Doesn’t Mean Recent Exposure
The most common explanation for a late diagnosis in a stable relationship is the parasite’s ability to remain asymptomatic for an extended period. The parasite can live in the body for months or even years without causing outward symptoms. This asymptomatic carriage means the infection could have been contracted long before the current relationship began.
Detection often occurs only when the parasite becomes active, causing symptoms to appear, or when a person undergoes routine screening. A positive test result is a finding of an existing infection, not necessarily a marker of recent transmission. The infection may have been passed between partners years ago, with both individuals remaining unaware until a change in the body’s natural balance caused a flare-up.
This latency means one partner may have been an asymptomatic carrier for a significant period. The current diagnosis may simply be the first time the parasite has caused symptoms in one person, making the other partner’s previous infection visible. Since up to 70% of infected individuals are asymptomatic, the infection can be passed back and forth unknowingly between stable partners.
Beyond Intercourse: Less Common Transmission Scenarios
While sexual contact is overwhelmingly the primary method of transmission, the parasite’s survival characteristics outside the body have led to speculation about other rare scenarios. Trichomonas vaginalis requires a warm, moist environment to survive, but it can persist for a few hours on damp surfaces. These extremely rare non-sexual transmission routes might involve sharing damp towels, wet clothing, or using contaminated toilet seats. However, public health experts stress that these instances are not a significant factor in the spread of the infection. The vast majority of cases are transmitted through skin-to-skin genital contact, which allows the parasite to transfer directly to the genital tract.
Next Steps After Diagnosis
The immediate next step after a positive diagnosis is to receive treatment and inform any recent sexual partners. Trichomoniasis is highly curable with prescription antibiotics, typically metronidazole or tinidazole. Treatment is usually administered as a single, large dose or a seven-day course of pills.
It is necessary for all current sexual partners to be tested and treated, even if they are not experiencing any symptoms. Treating only one partner creates a risk of “ping-pong” transmission, where the infection is passed back and forth, leading to reinfection. Abstinence from sexual activity is advised until seven days after both the individual and all partners have completed their full course of medication and all symptoms have resolved.