Trichomoniasis is a sexually transmitted disease (STD) caused by a tiny parasite. Also known as “trich” or “trick,” it infects both sexes but is more common in women. In the United States, about 5 to 10 percent of all women are infected with trichomoniasis, according to the National Women’s Health Resource Center. It is the most common nonviral STD.

Women can become infected with trichomoniasis through penis-to-vagina or vulva-to-vulva contact. Infection can also be spread through oral or anal sex or exposure to certain objects that are infested with the parasite. These objects include:

• Damp towels and washcloths
• Wet clothing, such as bathing suits
• Toilet seats

Trichomoniasis does not usually pose a serious health threat. In many cases, a woman will not experience any symptoms of infection. However, in some cases the condition may cause discomfort. Trichomoniasis increases the risk of becoming infected with other STDs, including the human immunodeficiency virus (HIV), which can cause acquired immune deficiency syndrome (AIDS). In addition, trichomoniasis can result in complications for pregnant women, such as premature labor and delivery and low birth weight of the infant.