Key facts
- Trichomoniasis is a common sexually transmitted infection (STI) caused by the protozoan Trichomonas vaginalis. It is treatable and curable.
- In 2020 there were approximately 156 million new cases of T. vaginalis infection among people aged 15–49 years old.
- In females, trichomoniasis is a common cause of vaginal discharge and is associated with poor birth outcomes and increased risk of pelvic inflammatory disease.
- In males, trichomoniasis is often asymptomatic and associated with increased risk of epididymitis, prostatitis and decreased sperm motility.
- Infection with T. vaginalis is also associated with increased risk of HIV acquisition.
Overview
Trichomonas vaginalis is a preventable and curable sexually transmitted protozoan that infects the urogenital tract.
Although the majority of infections are asymptomatic, more than 50% of women with Trichomonas vaginalis infection have vaginal discharge and about 10% of men have urethritis.
The parasite is transmitted during oral, vaginal and anal sex, and in some rare instances during delivery.
Correct and consistent use of condoms during sex can prevent trichomoniasis.
Symptoms
Most infections in men and women are asymptomatic. Symptomatic women can have vaginal discharge (yellow in colour), which may appear purulent. Other symptoms include a red and sore vagina. The person with the infection can also feel pain during intercourse and urination.
When T. vaginalis is present, a yellow or greenish and possibly frothy discharge can be observed in the vagina during a speculum examination by a health provider
Men are often asymptomatic, but some experience penile irritation and urethritis.
Diagnosis
Diagnosis based on signs and symptoms of vaginal or urethral discharge is often the most common approach in settings where laboratory diagnosis is not available.
Nucleic acid amplification tests (NAAT) are the most sensitive laboratory diagnostic method for detecting T. vaginalis. While vaginal swabs are the preferred samples, endocervical samples and urine can also be used for certain laboratory assays. Currently, NAAT is not widely available as a rapid point-of-care test.
Before the emergence of point-of-care antigen tests and NAAT, the primary method for detecting T. vaginalis was through culture. To confirm the absence of infection, the cultures must be incubated for up to seven days, which is a challenge for this method’s use.
In the past, diagnosing T. vaginalis often involved performing wet mount microscopy. While this is not the best method for trichomoniasis diagnosis, it is still commonly used in some settings.
Treatment
Trichomonas vaginalis is treatable and curable. People who suspect they may have trichomoniasis should speak to their healthcare provider. Treatment often requires metronidazole (first choice) or tinidazole administered orally.
Scope of the problem
Trichomonas vaginalis is the most common non-viral STI. There were an estimated 156 million new cases of T. vaginalis infection among people aged 15–49 years old in 2020 globally in 2020 (73.7 million in females, 82.6 million in males).
Approximately one third of new infections in this age group occur in the WHO African Region, followed by the Region of the Americas.
Transmission
Sexually active people can get trichomoniasis by having sex without a condom with a partner who has trichomoniasis.
Complications
Perinatal outcomes
Untreated T. vaginalis is linked to adverse birth outcomes, including low birth weight, preterm delivery and premature rupture of membranes. Although uncommon, perinatal transmission of T. vaginalis can occur, leading to vaginal and respiratory infections in newborns.
HIV transmission
T. vaginalis infections are linked to a 1.5 times increased risk of HIV acquisition.
Other STIs
Trichomonas vaginalis has been linked to the co-occurrence of various other STIs, including Chlamydia trachomatis, Neisseria gonorrhoeae, and human papillomavirus (HPV). It also demonstrates a similar epidemiologic connection with herpes simplex virus type 2 (HSV-2).
Infection with T. vaginalis can alter the usual vaginal microbiota, making it more susceptible to the development of bacterial vaginosis (BV). Around 40–60% of women with T. vaginalis also experience BV, and those with BV have an increased risk of contracting T. vaginalis.
Prevention
Trichomoniasis is a preventable condition.
The most effective method to prevent trichomoniasis and various other STIs is by consistently and correctly using condoms.
People diagnosed with trichomoniasis should inform their sexual partners to prevent further transmission. If that is not possible, they should request support from the health provider to notify their sexual partners.
WHO response
The WHO Global health sector strategies on HIV, viral hepatitis and STIs 2022–2030 aims for a 50% reduction in new cases of trichomoniasis by 2030. WHO collaborates with countries and partners to enhance people-centred STI case management methods, promote suitable treatment recommendations, and implement effective testing and partner services strategies.
WHO also supports the development of accessible and affordable high-quality diagnostics and treatment options, as well as advancements in vaccine development. Additionally, WHO focuses on improving country and global-level monitoring of new infections. As part of its efforts, WHO is updating recommendations for the treatment of T. vaginalis.
Although antimicrobial resistance in T. vaginalis is not widespread, WHO closely monitors patterns of potential antimicrobial resistance of this pathogen to inform treatment recommendations and national policies.