Trichomonas vaginalis is a single-celled parasite that causes trichomoniasis, a common sexually transmitted infection (STI). It infects the genitourinary tract in both men and women, affecting millions globally each year. The infection is treatable with medication.
How the Parasite Spreads
The Trichomonas vaginalis parasite primarily spreads through sexual contact, including vaginal intercourse, where it can be transmitted between the vagina and penis. Transmission can also occur through other forms of sexual contact, such as vulva-to-vulva contact. The parasite does not typically survive well outside the human body, meaning it is not spread through casual contact like hugging, sharing food or drinks, or using public toilets.
Transmission risk increases with certain behaviors. Having multiple sexual partners heightens the likelihood of exposure. A history of other sexually transmitted infections also elevates the risk of acquiring trichomoniasis. Inconsistent or incorrect use of condoms significantly contributes to the spread of this infection during sexual activity.
Common Signs of Infection
Many individuals infected with Trichomonas vaginalis experience no symptoms, making it possible to transmit the parasite unknowingly. About 70% of infected people do not show any signs. When symptoms do appear, they vary between sexes and range in severity.
In women, symptoms often involve changes in vaginal discharge, which may appear frothy, yellow-green, or gray and have a strong, unpleasant odor. Vaginal itching, burning, and redness around the vulva are also common. Some women report discomfort or pain during urination or sexual intercourse, indicating inflammation of the urethra or vagina. These symptoms can sometimes be mistaken for other vaginal infections, such as bacterial vaginosis or yeast infections.
Men are even more likely to be asymptomatic than women. When symptoms occur in men, they are generally milder and may include itching or irritation inside the penis. Some men might experience a slight discharge from the penis or a burning sensation after urinating or ejaculating. Due to the often subtle or absent symptoms in men, the infection can go undiagnosed and untreated for extended periods, potentially leading to continued transmission.
Identifying and Treating the Infection
Diagnosing Trichomonas vaginalis involves examining a sample from the infected area. For women, a vaginal swab is collected; for men, a urine sample or urethral swab can be used. Microscopic examination of fresh samples (wet mount) can sometimes identify the moving parasites. However, this method has limitations in sensitivity.
More sensitive diagnostic methods include rapid diagnostic tests and nucleic acid amplification tests (NAATs). NAATs are accurate and can detect the parasite’s genetic material, even in small amounts. These tests help confirm the infection, particularly in asymptomatic individuals or when symptoms are mild.
Trichomoniasis is a curable infection, typically treated with oral antibiotics. The standard treatment involves a single dose of metronidazole or tinidazole, which are highly effective. It is important for all sexual partners to receive treatment at the same time, even if they show no symptoms, to prevent reinfection. Patients should avoid sexual activity until both they and their partners have completed treatment and any symptoms have resolved.
Following treatment, a retest is often recommended within three months, especially for women, to confirm eradication. This retesting helps ensure treatment success and prevent reinfection. Persistent or recurring infections may require alternative dosing or different medications, emphasizing the need for follow-up with a healthcare provider.
Preventing Future Infections
Preventing Trichomonas vaginalis and other sexually transmitted infections involves adopting safer sexual practices. Consistent and correct use of condoms during every sexual encounter reduces the risk of transmission. Limiting the number of sexual partners also lowers exposure risk to STIs.
Regular STI screenings are important, especially for individuals who are sexually active or have new partners. Open communication with sexual partners about STI status and testing history can help create a safer environment.