Trichomoniasis is a common sexually transmitted disease caused by a parasite of Trichomonas vaginalis.


The pathogen is Trichomonas vaginalis that is pyriform, 10 - 30μm long; with 4 flagella in the head, undulating membrane in the body, and columella in the tail.

Trichomonas vaginalis is very adaptable to different environments and can grow and propagate at 25 ℃ - 42 ℃. The pathogen can survive for 21 days at 3 ℃ - 5 ℃ and for 20 - 60 minutes at 46 ℃.

Trichomoniasis is mainly transmitted through sexual contacts, as well as indirect transmissions, such as public baths, bathtub, swimming pools, toilets, clothes, appliances, and dressings.

Signs and Symptoms

The incubation period is 4 - 28 days.

The manifestations are increased, odorous, yellowish green vaginal discharge; pruritus, burning sensation, dyspareunia, dysuria, frequent urination, and lower abdominal pain. In the physical examinations, vulvovaginal erythema, edema, foamy yellowish grey or green vaginal discharge, and increased pH (pH>6) can be detected, and about 2% of patients have a strawberry cervix. 85% of patients are asymptomatic, 1/3 of patients develop symptoms within 6 months after infection, and 90% of patients have urinary infections.

Video 1 trichomoniasis

Laboratory examinations

The examinations include microscopy, nucleic acid amplification test, cultures, and antigen detection.


On the basis of clinical manifestations and results of laboratory examinations, the disease can be diagnosed.


The recommended treatment regimen is metronidazole 2g orally in a single dose, or tinidazole 2g orally in a single dose, and the alternative is metronidazole 400mg orally twice daily for 7 days.

The regimen for reinfection is metronidazole 2g or tinidazole 2g orally in a single dose.

If the recommended treatment failed, and there is not reinfection, the regimen is tinidazole 2g orally once daily for 7 days.

The regimen for pregnant patients is metronidazole 400mg orally twice a day for 7 days, or metronidazole 2g orally in a single dose.

The regimen for lactating patients is the same as those of pregnant patients. Lactation should be avoided within 12 - 24 hours after oral metronidazole, and lactation should be avoided within 3 days after oral tinidazole.