Trichomoniasis, sometimes referred to as "trich", is a common cause of vaginitis

Vaginitis

Vaginitis is an inflammation of the vagina. It can result in discharge, itching and pain, and is often associated with an irritation or infection of the vulva. It is usually due to infection. The three main kinds of vaginitis are bacterial vaginosis , vaginal candidiasis, and trichomoniasis. A...

. It is a sexually transmitted disease

Sexually transmitted disease

Sexually transmitted disease , also known as a sexually transmitted infection or venereal disease , is an illness that has a significant probability of transmission between humans by means of human sexual behavior, including vaginal intercourse, oral sex, and anal sex...

, and is caused by the single-celled protozoan parasite Trichomonas vaginalis

Trichomonas vaginalis

Trichomonas vaginalis is an anaerobic, flagellated protozoan, a form of microorganism. The parasitic microorganism is the causative agent of trichomoniasis, and is the most common pathogenic protozoan infection of humans in industrialized countries. Infection rates between men and women are the...

producing mechanical stress on host cells and then ingesting cell fragments after cell death. Trichomoniasis is primarily an infection of the urogenital tract

Genitourinary system

In anatomy, the genitourinary system or urogenital system is the organ system of the reproductive organs and the urinary system. These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathways, like the male urethra...

; the most common site of infection is the urethra

Urethra

In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...

 and the vagina

Vagina

The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...

 in women.
Typically, only women experience symptoms associated with Trichomonas infection.