STI | Trichomoniasis

Trichomoniasis is a common, curable sexually transmitted infection. Many people with trichomoniasis don’t experience symptoms, which increases transmission.

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Trichomonas vaginalis (T. vaginalis) is a protozoan pathogen that causes trichomoniasis, a common, curable sexually transmitted infection.


According to the Centers for Disease Control and Prevention (CDC), there are about 2.6 million trichomoniasis infections in the United States. The World Health Organization (WHO) estimates there were more than 156 million cases worldwide in 2020. About 70 percent of individuals infected with T. vaginalis do not experience symptoms.


Symptoms of trichomoniasis in women can include:

  • Vaginal discharge
  • Pain, itching, burning of genitals
  • Dysuria

Symptoms of trichomoniasis in men can include:

  • Irritation or itching in the penis
  • Dysuria
  • Urethral discharge

Symptoms fluctuate in intensity and may persist for weeks or months. For women, symptoms usually worsen during menses and pregnancy. Left untreated, trichomoniasis may increase the risk of preterm birth and low birth weight as well as lead to infertility in women.

T. vaginalis  is contagious and transmitted through sexual contact. People with asymptomatic trichomoniasis can infect a partner. Being infected with T. vaginalis can increase the risk of getting or spreading HIV and other sexually transmitted infections.

The likelihood of acquiring T. vaginalis  is directly related to the number of sexual contacts and non-venereal transmission is uncommon. However, transfer of organisms can occur through shared bathwater, damp washcloths and towels, damp toilet seats and public pools that are not clean.

There is no vaccine available for T. vaginalis. The most effective prevention is abstinence; however, sexually active persons can limit risk of infection by practicing safer sex including using latex condoms or polyurethane dental dams to avoid contact with sexual fluids.

Because only 30 percent of people with T. vaginalis  have symptoms, many people spread the disease without knowledge of infection. Getting tested and receiving treatment is recommended to help prevent the problem of reinfection.

Diagnostic testing is recommended for all women presenting symptoms of vaginitis. The diagnosis of trichomoniasis traditionally was based on morphologic identification of the organism in a wet mount preparation of a swab from vaginal discharge fluid in women or urethral exudate in men. Microscopic evaluation of wet mounts has a positive predictive value negative predictive value of only 60 percent, which can be increased to over 80 percent with direct immunofluorescent antibody staining. Parasitic culture, though more sensitive, requires several days to complete and is infrequently done. A rapid diagnostic point-of-care dipstick test is available and has reasonably high sensitivity and very high specificity. Molecular diagnostic methods based on PCR offer high sensitivity and specificity.

Treatment with oral antibiotics is highly effective for curing trichomoniasis. Medications include:

  • Metronidazole
  • Tinidazole
  • Secnidazole

Treatment of sexual partners is recommended to reduce reinfection rates.