Trichomonas vaginalis

Trichomonas vaginalis is a Flagellate that is a significant cause of vaginitis / urethritis.

Disease / Pathogenesis

The organism is one of the major causes of non-specific vaginitis / urethritis. Though considered a sexually transmitted disease, it can be contracted by sharing infected clothing such as underwear or towels. Infections generally increase in incidence.

Location in the Host

Trichomonas vaginalis is found in the urethra and vaginal/cervical sites of the host.

Geographic Distribution

worldwide distribution

Life Cycle

The life cycle of Trichomonas vaginalis is shown below.

Image courtesy of CDC

Morphology & Diagnosis

The detection of Trichomonas vaginalis has traditionally been by directly observing microscopically the motile flagellates in spun down urine and / or vaginal – urethral saline washes. The detection by direct observation however lacks sensitivity and many infections are missed.

Advances in PCR and other DNA technique technologies have become more commonly used in laboratories to detect the presence of the parasite. This provides the sensitivity lacking in direct observation techniques. As the pricing of these tests become more competitive and economically practical, they will most likely replace in many laboratories, direct observation tests.


Trichomonas vaginalis seen in a urine sediment – located in center – note the flagella at about 11 o’clock on the parasite. Photo by W. Vientos