trichomoniasis

Trichomoniasis, or trich, is a sexually transmitted infection caused by the flagellated protozoan parasite Trichomonas vaginalis. It is one of the most common non-viral sexually transmitted infections worldwide and can affect people of any age who are sexually active.

Symptoms vary and many infected people are asymptomatic. In women, possible signs include vaginal discharge (often yellow-green, frothy), itching or irritation of the vulva, and burning with urination. Some may experience abdominal discomfort or cervicitis. In men, symptoms are less common but can include urethral discharge, burning with urination, or irritation of the urethra; most cases are asymptomatic.

Transmission occurs primarily through sexual contact. Non-sexual transmission is rare, and newborns can be infected during birth, though this is uncommon. In pregnant people, infection can be associated with adverse outcomes such as preterm birth.

Diagnosis is usually made with nucleic acid amplification tests (NAATs) on vaginal swabs, endocervical swabs, urethral samples, or urine. NAATs are preferred due to higher sensitivity; microscopy and culture are less reliable, especially in men.

Treatment involves anti‑parasite medications. The usual regimens are metronidazole or tinidazole, given to the patient and to sex partners. Typical doses include metronidazole 500 mg twice daily for seven days or a single 2 g dose; tinidazole 2 g single dose. Patients should avoid alcohol during treatment and for 24–72 hours after completing metronidazole due to potential interactions. Partners should be treated even if asymptomatic, and sexual activity should be avoided until treatment is complete.

Prevention focuses on safe sex practices, including consistent condom use and regular testing in high‑risk groups. In pregnancy, treatment is advised to reduce risks to the fetus.