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If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
Trichomoniasis is the most common non-viral sexually transmitted infection (STI) globally, accounting for an estimated 156 million cases (Rowley, 2019). And in the U.S. alone, more than 3.7 million people have trich. Yet, many haven’t heard of it and may not even know they have it (Partin, 2021).
About 80% of people who have trichomoniasis don’t have symptoms and don’t know they could be giving it to a partner. Though usually mild and treatable, trich can impact pregnancy, fertility, and increase the risk of getting other STIs and cervical cancer (Menezes, 2016; Yang, 2018).
What is trichomoniasis?
Unlike chlamydia or gonorrhea, which are caused by bacterial infections, trichomoniasis is a sexually transmitted infection caused by the parasite trichomonas vaginalis.
This parasite is very small, and it lives in the human genitourinary tract (the vagina or penis), where it can survive—often unnoticed—for months or years. There, it damages and consumes cells, which can lead to red dots of raw skin inside the vagina (Kissinger, 2015).
How do you get trichomoniasis?
The transmission of trich nearly always occurs through some type of sexual activity or the exchange of body fluids in the genital area. Vaginal sex is the most common route. Vulva-to-vulva sexual contact can also lead to a trich infection, along with passing vaginal fluids or semen via fingers or sex toys. Oral and anal sex, however, rarely transmit the infection (Carter-Wicker, 2016).
And while non-sexual transmission is very rare, trichomonas vaginalis can form cyst-like structures that allow for survival outside the human body in wet or moist areas for a short time. Researchers say this may explain rare cases of reported non-sexual transmission in bath water or on towels (Beri, 2020).
Symptoms of trichomoniasis
Only about 20% of people notice trich symptoms. These may present from 4 to 28 days after exposure or develop much later. Symptoms can also come and go (Menezes, 2016).
Trichomoniasis symptoms in women include (Menezes, 2016):
- Increased vaginal discharge that can be clear, yellow, or greenish (sometimes frothy) that may have a fishy odor
- Itching, irritation, redness, pain
- Discomfort or burning during urination
- Discomfort or pain during sex
STI vs. STD: what’s the difference?
Trichomoniasis symptoms in men include (Menezes, 2016):
- Itching or irritation inside the penis (urethra)
- Pain during urination
- Mild itching or burning after ejaculation
- Discharge from the penis (clear or containing mucus/pus)
It’s important to reach out to your healthcare provider if you notice any of these symptoms so that you can receive the right diagnosis and treatment.
Risks of trichomoniasis
As with other STIs, there are health risks associated with trich. Trichomoniasis may increase the risk of preterm labor, infertility, contracting other STIs, and cervical cancer. These risks are highest when trich remains untreated, emphasizing the importance of recognizing symptoms and receiving the appropriate treatment.
Preterm labor and low birth weight
Pregnant women with trich are at risk for preterm delivery, having low birth weight infants, and rupture of the amniotic sac that surrounds the baby before week 37 of pregnancy. If the sac breaks, it can increase the risk of infection and having the baby early (Van Gerwen, 2021).
Trich can also be spread to a baby during birth, impacting the baby’s lungs or urinary tract. These infections often resolve on their own but may require treatment (Coleman, 2013).
Infertility or subfertility
Untreated trichomoniasis is linked to inflammation and decreased fertility in men and women. In men, trich can cause urethritis, prostatitis, and epididymitis. These conditions can negatively affect male fertility. Research also shows trichomonas vaginalis can reduce sperm motility (Henkel, 2021; Schuppe, 2017).
In women, untreated trich has been linked to pelvic inflammatory disease (PID), which can scar the fallopian tubes, preventing the fertilization of eggs (Wiringa, 2020).
Can STDs cause infertility in men and women?
Sexually transmitted infections
Trichomonas vaginalis creates small sores inside the vagina, including around the cervix. Researchers believe by breaking down the vaginal wall, a trich infection makes it easier to contract sexually transmitted infections such as HIV (human immunodeficiency virus) and HPV (human papillomavirus) (Coleman, 2013; Belfort, 2021).
Research shows trich infections lead to an increased risk of cervical cancer. Studies show inflammation may play a role by making HPV infections—which are linked to cervical cancer—more severe (Belfort, 2021; Yang, 2018).
How is trichomoniasis diagnosed?
Even if you do notice signs of infection, symptoms alone are not enough to diagnose trich. A diagnosis typically includes one of the following tests (Schumann, 2021):
- Nucleic acid amplification test: Called NAAT for short, some STI and HIV clinics currently use these tests for routine screening programs. NAAT has been a gold standard for testing for gonorrhea and chlamydia. The test often shows greater than 90% sensitivity and specificity when testing for trichomonas vaginalis.
- Wet Mount (microscope): This traditional approach uses a microscope to find moving trichomonas vaginalis. It’s convenient and low cost. However, it’s only about 40%–60% effective since it only shows what’s in a small sample.
During a consultation, a healthcare provider will usually ask about your sexual history and symptoms. They may suggest ruling out other conditions such as bacterial vaginosis if you’re a woman or prostatitis if you’re a man (Schumann, 2021).There are three separate treatment strategies for trich that involve oral medications. Healthcare providers typically use one of the following approaches (Schumann, 2021):
- A single dose (2-gram) of metronidazole
- A single dose (2-gram) of tinidazole
- For patients with HIV infection, a 7-day course of 500 mg metronidazole twice daily may be recommended.
It’s important for pregnant women to receive treatment to prevent preterm labor.
You should not consume alcohol while using these medications. Healthcare providers typically advise avoiding alcohol until 24 hours after the final dose of metronidazole and 72 hours after the tinidazole dose.
Pelvic inflammatory disease: causes, symptoms, and treatment
Avoiding trichomoniasis reinfection
To avoid reinfection, sexual partners should receive treatment simultaneously and avoid sex until the treatment is complete. Expedited partner therapy laws (in many states) may allow a provider to prescribe treatment to a sexual partner without an exam or patient relationship.
Additionally, your healthcare provider may ask you to schedule a follow-up appointment after about two weeks to ensure your body has cleared the infection. The CDC recommends follow-up testing within three months from the initial test. Follow-ups are important because some people have drug-resistant strains of trich, which may require a different medication.
Healthcare providers outline the following ways to reduce your chances of getting trichomoniasis if you’re sexually active:
- Talk with your partner about risks for STIs.
- Use condoms correctly. Research shows the consistent and correct use of condoms does provide a good amount of protection against STIs like trich (Crosby, 2012).
- Assume any fluids from the vagina or penis may harbor trichomonas vaginalis; experts suggest not sharing intimate items like sex toys and point out that you don’t have to have intercourse to be infected.
Condom sizing: how to choose the right condom size
When to see a healthcare provider
Any time you have symptoms of an STI or concerns about your sexual health, it’s important to seek medical advice. A healthcare provider may ask about your sex partners and whether you are pregnant or plan to become pregnant.
Ask your healthcare provider about what types of STIs you should be aware of and whether you should have a trichomoniasis screening. If you receive a diagnosis of trichomoniasis, know that it’s common and treatable.
- Belfort, I. K., Cunha, A. P., Mendes, F. P., Galvão-Moreira, L. V., Lemos, R. G., de Lima Costa, L. H., et al. (2021). Trichomonas vaginalis as a risk factor for human papillomavirus: A study with women undergoing cervical cancer screening in a Northeast region of Brazil. BMC Women’s Health, 21(1). doi: 10.1186/s12905-021-01320-6. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6653813/
- Beri, D., Yadav, P., Devi, H. R., Narayana, C., Gadara, D., & Tatu, U. (2020). Demonstration and characterization of cyst-like structures in the life cycle of trichomonas vaginalis. Frontiers in Cellular and Infection Microbiology, 9. doi: 10.3389/fcimb.2019.00430. Retrieved from https://www.frontiersin.org/articles/10.3389/fcimb.2019.00430/full
- Carter-Wicker, K., Utuama, O., & Omole, F. (2016). Can trichomoniasis cause pharyngitis? A case report. SAGE Open Medical Case Reports, 4. doi: 10.1177/2050313×16682132. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5308532/
- Coleman, J. S., Gaydos, C. A., & Witter, F. (2013). Trichomonas vaginalis vaginitis in obstetrics and gynecology practice. Obstetrical & Gynecological Survey, 68(1), 43–50. doi: 10.1097/ogx.0b013e318279fb7d. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3586271/
- Crosby, R. A., Charnigo, R. A., Weathers, C., Caliendo, A. M., & Shrier, L. A. (2012). Condom effectiveness against non-viral sexually transmitted infections: A prospective study using Electronic Daily Diaries. Sexually Transmitted Infections, 88(7), 484–489. doi: 10.1136/sextrans-2012-050618. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3502658/#!po=76.3158
- Henkel, R. (2021). Long-term consequences of sexually transmitted infections on men’s sexual function: A systematic review. Arab Journal of Urology, 19(3), 411–418. doi: 10.1080/2090598x.2021.1942414. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8451632/
- Kissinger, P. (2015). Epidemiology and treatment of trichomoniasis. Current Infectious Disease Reports, 17(6). doi: 10.1007/s11908-015-0484-7. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5030197/
- Menezes, C. B., Amanda Piccoli Frasson, A. P., & Tasca, T. (2016). Trichomoniasis – are we giving the deserved attention to the most common non-viral sexually transmitted disease worldwide? Microbial Cell, 3(9), 404–418. doi: 10.15698/mic2016.09.526. Retrieved from https://microbialcell.com/researcharticles/trichomoniasis-are-we-giving-the-deserved-attention-to-the-most-common-non-viral-sexually-transmitted-disease-worldwide/
- Partin, A. (n.d.). Trichomoniasis – an overview | ScienceDirect Topics. Retrieved Feb. 18, 2022 from https://www.sciencedirect.com/topics/medicine-and-dentistry/trichomoniasis
- Rowley, J., Vander Hoorn, S., Korenromp, E., Low, N., Unemo, M., Abu-Raddad, L. J., et al. (2019). Chlamydia, gonorrhoea, trichomoniasis and syphilis: Global prevalence and incidence estimates, 2016. Bulletin of the World Health Organization, 97(8). doi: 10.2471/blt.18.228486. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6653813/
- Schumann, J. A. (2021). Trichomoniasis. [Updated Dec. 13, 2021]. In: StatPearls [Internet]. Retrieved Feb. 18, 2022 from https://www.ncbi.nlm.nih.gov/books/NBK534826/
- Schuppe, H. C., Pilatz, A., Hossain, H., Diemer, T., Wagenlehner, F., & Weidner, W. (2017). Urogenital infection as a risk factor for male infertility. Deutsches Ärzteblatt International. doi: 10.3238/arztebl.2017.0339. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5470348/
- Van Gerwen, O. T., Craig‐Kuhn, M. C., Jones, A. T., Schroeder, J. A., Deaver, J., Buekens, P., et al. (2021). Trichomoniasis and adverse birth outcomes: A systematic review and meta‐analysis. BJOG: An International Journal of Obstetrics & Gynaecology, 128(12), 1907–1915. doi: 10.1111/1471-0528.16774. Retrieved from https://pubmed.ncbi.nlm.nih.gov/34036690/
- Wiringa, A. E., Ness, R. B., Darville, T., Beigi, R. H., & Haggerty, C. L. (2019). Trichomonas vaginalis, endometritis and sequelae among women with clinically suspected pelvic inflammatory disease. Sexually Transmitted Infections, 96(6), 436–438. doi: 10.1136/sextrans-2019-054079. Retrieved from https://pubmed.ncbi.nlm.nih.gov/31719170/
- Yang, S., Zhao, W., Wang, H., Wang, Y., Li, J., & Wu, X. (2018). Trichomonas vaginalis infection-associated risk of cervical cancer: A meta-analysis. European Journal of Obstetrics & Gynecology and Reproductive Biology, 228, 166–173. doi: 10.1016/j.ejogrb.2018.06.031. Retrieved from https://pubmed.ncbi.nlm.nih.gov/29980111/
Dr. Steve Silvestro is a board-certified pediatrician and Senior Manager, Medical Content & Education at Ro.