For 95-97% of cases, infection is resolved after one dose of metronidazole.[26][35] Studies suggest that 4-5% of trichomonas cases are resistant to metronidazole, which may account for some “repeat” cases.[33][9] Without treatment, trichomoniasis can persist for months to years in women, and is thought to improve without treatment in men.[9] Women living with HIV infection have better cure rates if treated for 7 days rather than with one dose.[31][36]
Trichomoniasis is a sexually transmitted infection (STI) caused by a parasite. The parasite is spread most often through vaginal, oral, or anal sex. It is one of the most common STIs in the United States and affects more women than men. It is easily treated with antibiotics, but many women do not have symptoms. If left untreated, trichomoniasis can raise your risk of getting HIV.

For 95-97% of cases, infection is resolved after one dose of metronidazole.[26][35] Studies suggest that 4-5% of trichomonas cases are resistant to metronidazole, which may account for some “repeat” cases.[33][9] Without treatment, trichomoniasis can persist for months to years in women, and is thought to improve without treatment in men.[9] Women living with HIV infection have better cure rates if treated for 7 days rather than with one dose.[31][36]
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]
Evidence from a randomized controlled trials for screening pregnant women who do not have symptoms for infection with trichomoniasis and treating women who test positive for the infection have not consistently shown a reduced risk of preterm birth.[29][30] Further studies are needed to verify this result and determine the best method of screening. In the US, screening of pregnant women without any symptoms is only recommended in those with HIV as trichomonas infection is associated with increased risk of transmitting HIV to the fetus.[31]

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.
Bacterial vaginosis is an abnormal vaginal condition with signs and symptoms of vaginal discharge, vaginal odor, and vaginal pain. Bacterial vaginosis results from an overgrowth of normal bacteria in the vagina. Although it may cause some disturbing symptoms (discharge and odor), it is not dangerous and cannot be passed by sex. Diagnosis becomes important to exclude serious infections like gonorrhea and Chlamydia. Many treatment options are available such as oral antibiotics and vaginal gels.
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]
Evidence from a randomized controlled trials for screening pregnant women who do not have symptoms for infection with trichomoniasis and treating women who test positive for the infection have not consistently shown a reduced risk of preterm birth.[29][30] Further studies are needed to verify this result and determine the best method of screening. In the US, screening of pregnant women without any symptoms is only recommended in those with HIV as trichomonas infection is associated with increased risk of transmitting HIV to the fetus.[31]

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.

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]
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