Trichomoniasis overview

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Maliha Shakil, M.D. [2]

Overview

Trichomoniasis is a common sexually transmitted disease that affects 7.4 million previously unaffected Americans each year. It is caused by a single-celled protozoan parasite Trichomonas vaginalis. Trichomonas vaginalis was first discovered by Dr. Alfred François Donné, a French physician, in 1836. Trichomoniasis is primarily an infection of the genitourinary tract. The urethra is the most common site of infection in men, and the vagina is the most common site of infection in women. It is most common in women and uncircumcised men. For uncircumcised men, the most common site for the infection is the tip of the penis.

Historical Perspective

Trichomonas vaginalis was first discovered by Dr. Alfred François Donné, a French physician, in 1836.

Causes

Trichomoniasis is caused by the single-celled protozoan parasite, Trichomonas vaginalis. The vagina is the most common site of infection in women, and the urethra is the most common site of infection in men.

Differential Diagnosis

Trichomoniasis must be differentiated from other causes of vaginitis such as bacterial vaginosis, vulvovaginal candidiasis, and atrophic vaginitis.

Epidemiology and Demographics

Trichomoniasis is the most common curable STD in young, sexually active women. An estimated 7.4 million new cases occur each year in women and men. In 2008, the incidence of trichomoniasis was estimated to be 358 cases per 100,000 individuals in the United States. Females are more commonly affected with trichomoniasis than males. Trichomoniasis usually affects African American individuals. Caucasian individuals are less likely to develop trichomoniasis. In the United States, the highest prevalence of trichomonas infection in US women is seen among African-Americans with rates ranging from 13–51%.

Risk Factors

Common risk factors in the development of trichomoniasis include multiple sexual partners, unprotected sexual activity, intravenous drug use, and coexisting veneral disease.

Natural History, Complications, and Prognosis

If left untreated, women with trichomoniasis may progress to develop infection of the adnexa, endometrium, and Skene and Bartholin glands. In men, it can cause epididymitis, prostatitis, and decreased sperm cell motility. Complications of trichomoniasis include pelvic inflammatory disease, increased risk of HIV, increased risk of cervical cancer, increased risk of prostate cancer, and pregnancy related complications such as low birth weight, preterm delivery, and premature rupture of membranes. The prognosis of trichomoniasis is generally excellent with treatment.

Diagnosis

History and Symptoms

A detailed and thorough sexual history from the patient is necessary. Specific areas of focus when obtaining a history from the patient include number and type of sexual partners (new, casual, or regular), contraception use, and previous history of trichomoniasis or other sexually transmitted diseases. The majority of women (85%) and men (77%) with trichomoniasis are asymptomatic. One third of asymptomatic women become symptomatic within 6 months. Common symptoms of trichomoniasis in women include vaginal discharge (which is often diffuse, malodorous, and yellow-green or gray in color), painful urination (dysuria), vulvar irritation and itching, abdominal pain and discomfort during sexual intercourse. Symptoms of trichomoniasis in males include clear or mucopurulent urethral discharge, painful urination, and pruritus or a burning sensation following sexual intercourse.

Physical Examination

Patients with trichomoniasis are usually well-appearing. Common physical examination findings of trichomoniasis include strawberry cervix and a foul-smelling, frothy, and mucopurulent green or gray vaginal discharge. In males, there may be scanty, mucopurulent urethral discharge.

Laboratory Findings

Laboratory tests used in the diagnosis of trichomoniasis include saline microscopy, culture, and nucleic acid amplification tests (NAATs).

Treatment

Medical Therapy

Trichomoniasis can usually be cured with the prescription drug, metronidazole, given by mouth in a single dose. The symptoms of trichomoniasis in infected men may disappear within a few weeks without treatment. However, an infected man, even a man who has never had symptoms or whose symptoms have stopped, can continue to infect or re-infect a female partner until he has been treated. Therefore, both partners should be treated at the same time to eliminate the parasite. Persons being treated for trichomoniasis should avoid sex until they and their sex partners complete treatment and have no symptoms. Metronidazole can be used by pregnant women. Having trichomoniasis once does not protect a person from getting it again. Following successful treatment, people can still be susceptible to re-infection.