Most people infected with Trichomonas vaginalis do not have any symptoms and can be undetected for years.[6] Symptoms experienced include pain, burning or itching in the penis, urethra (urethritis), or vagina (vaginitis). Discomfort for both sexes may increase during intercourse and urination. For women there may also be a yellow-green, itchy, frothy, foul-smelling ("fishy" smell) vaginal discharge. In rare cases, lower abdominal pain can occur. Symptoms usually appear within 5 to 28 days of exposure.[7] Sometimes trichomoniasis can be confused with chlamydia because the symptoms are similar.[8]
Trichomoniasis is a sexually transmitted infection (STI) which is most often spread through vaginal, oral, or anal sex.[1] It can also spread through genital touching.[1] People who are infected may spread the disease even when symptoms are not present.[2] Diagnosis is by finding the parasite in the vaginal fluid using a microscope, culturing the vagina or urine, or testing for the parasite's DNA.[1] If present other STIs should be tested for.[1]
The first is known as saline microscopy. This is the most commonly used method and requires an endocervical, vaginal, or penile swab specimen for examination under a microscope.[17] The presence of one or multiple trichomonads constitutes a positive result. This method is cheap but has a low sensitivity (60-70%) often due to an inadequate sample, resulting in false negatives.[18][19]
There were about 58 million cases of trichomoniasis in 2013.[38] It is more common in women (2.7%) than males (1.4%).[39] It is the most common non-viral STI in the U.S., with an estimated 3.7 million prevalent cases and 1.1 million new cases per year.[40][41] It is estimated that 3% of the general U.S. population is infected,[21][42] and 7.5-32% of moderate-to-high risk (including incarcerated) populations.[43][44][45][46][47][48][49][50]
Use of male condoms or female condoms may help prevent the spread of trichomoniasis,[22] although careful studies have never been done that focus on how to prevent this infection. Infection with Trichomoniasis through water is unlikely because Trichomonas vaginalis dies in water after 45–60 minutes, in thermal water after 30 minutes to 3 hours and in diluted urine after 5–6 hours.[23]

The advent of new, highly specific and sensitive trichomoniasis tests present opportunities for new screening protocols for both men and women.[24][27] Careful planning, discussion, and research are required to determine the cost-efficiency and most beneficial use of these new tests for the diagnosis and treatment of trichomoniasis in the U.S., which can lead to better prevention efforts.[24][27]