Worldwide, trichomoniasis is the most common curable sexually transmitted disease (STD). Caused by the parasite Trichomonas vaginalis, the condition usually causes itching and a foul-smelling discharge in women, as well as pain during urination or sex. In men, it is often asymptomatic.
Trichomoniasis can be diagnosed through a number of different tests including urine tests and cultures performed by a doctor or self-collected vaginal and urethral swabs. However, trichomoniasis is most commonly diagnosed by direct observation under a microscope, using a test known as a wet mount.
Because trichomoniasis can be more difficult to diagnose in men than in women, some doctors will presumptively treat an infected woman's male sexual partner, even if he does not test positive, in order to keep him from reinfecting her after she finishes treatment.
Sometimes STD treatment isn't just about taking a drug. When you're being treated for trichomoniasis, you also have to give the drug enough time to eradicate the parasite from your system. This is why when you're undergoing trichomoniasis treatment, you are generally told to wait at least a week after you and your partner have begun treatment to start having sex. The goal is to make certain that the STD treatment has enough time to work in both of your bodies so that you can avoid reinfecting each other.
Another reason to wait a week after treatment to start having sex is to see if STD symptoms reappear. Trichomoniasis treatment is not always 100 percent effective, and if an infection is knocked back but not eliminated, a week gives symptoms some chance to show up again. Then one or both partners can return for treatment. Treatment failure is more common with single-dose treatments than it is with multiple-dose treatments. In addition, there is some data suggesting that tinidazole is more effective than metronidazole, and using tinidazole may decrease the chance of a recurrence.
Although it is a better idea to hold off on sex until treatment has time to work and the infection has been eliminated, if you simply can't wait to have sex, then it is important at least to practice safe sex during treatment. It may not be ideal, but with STDs that are transmitted by fluids and treated with antibiotics, the risk of re-infection is usually relatively low. However, if you are being treated with a topical creme or suppository, safe sex may not be an option. Some of those products degrade latex condoms and other barriers.
If you are concerned about your ability to abstain from sex during STD treatment, talk to your doctor about the potential risks for you and your partner, and seek his or her advice about how to minimize them.
An Important Note About Trichomoniasis and HIV: There is some research suggesting that trichomoniasis infections can elevate viral load in HIV patients. This could increase the possibility of spreading HIV to a sexual partner. Conversely, research suggests that individuals with trichomoniasis also have a higher susceptibility to HIV infection than people who do not have trichomoniasis.
Because of the complex relationship between trichomoniasis and HIV, trichomoniasis treatment could play an important role in reducing the spread of HIV in high-risk populations. Because of this and the increased efficacy of multi-dose trichomoniasis treatments in HIV-positive women, it may be worth asking for a seven-day treatment regimen instead of a single-dose treatment if you are an HIV-positive woman with trichomoniasis. However, if you do not believe that you are capable of taking seven days of pills correctly, then you should stick to the single-dose treatment and consider being re-tested after a month to see if it worked.
Bachmann LH, et al. (2011) "Trichomonas vaginalis genital infections: progress and challenges." Clin Infect Dis. 53 Suppl 3:S160-72.