The parasite passes from an infected person to an uninfected person during sex. In women, the most commonly infected part of the body is the lower genital tract (vulva, vagina, cervix, or urethra). In men, the most commonly infected body part is the inside of the penis (urethra). During sex, the parasite usually spreads from a penis to a vagina, or from a vagina to a penis. It can also spread from a vagina to another vagina. It is not common for the parasite to infect other body parts, like the hands, mouth, or anus. It is unclear why some people with the infection get symptoms while others do not. It probably depends on factors like a person’s age and overall health. Infected people without symptoms can still pass the infection on to others.
Your sex partner(s) should be treated at the same time you are being treated. This increases the cure rate and reduces the possibility of further transmission or reinfection. Sexual intercourse should be avoided during treatment until symptoms are gone and until partners have been treated. It is best to avoid sex for 1 week after treatment with a single dose of metronidazole. Male partners may not have symptoms but still need treatment.
^ Jump up to: a b Vos T, Allen C, Arora M, Barber RM, Bhutta ZA, Brown A, Carter A, et al. (GBD 2015 Disease and Injury Incidence and Prevalence Collaborators) (October 2016). "Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015". Lancet. 388 (10053): 1545–1602. doi:10.1016/S0140-6736(16)31678-6. PMC 5055577. PMID 27733282.
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]
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]
Currently there are no routine standard screening requirements for the general U.S. population receiving family planning or STI testing.[24][25] The Centers for Disease Control and Prevention (CDC) recommends Trichomoniasis testing for females with vaginal discharge[26] and can be considered for females at higher risk for infection or of HIV-positive serostatus.[24]
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]
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]

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]
Watchful waiting is a period of time during which you and your doctor observe your symptoms or condition without using medical treatment. Watchful waiting isn't appropriate if you think you have trichomoniasis (trich). In most cases, trich should be treated to prevent transmitting this sexually transmitted infection to others and to prevent some problems that can happen if you are pregnant.
Use condoms. Condoms are the best way to prevent STIs when you have sex. Because a man does not need to ejaculate (come) to give or get trichomoniasis, make sure to put the condom on before the penis touches the vagina, mouth, or anus. Other methods of birth control, like birth control pills, shots, implants, or diaphragms, will not protect you from STIs. Get tested. Be sure you and your partner are tested for STIs. Talk to each other about the test results before you have sex.
Your sex partner(s) should be treated at the same time you are being treated. This increases the cure rate and reduces the possibility of further transmission or reinfection. Sexual intercourse should be avoided during treatment until symptoms are gone and until partners have been treated. It is best to avoid sex for 1 week after treatment with a single dose of metronidazole. Male partners may not have symptoms but still need treatment.
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