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"Trich" redirects here. For the hair-pulling disorder, see Trichotillomania.
Not to be confused with Trichinosis or Trichuriasis.
Classification and external resources
Trichomonas pap test.jpg
Micrograph showing a positive result for trichomoniasis. A trichomonas organism is seen on the top-right of the image.
ICD-10 A59
ICD-9 131,007.3
DiseasesDB 13334
MedlinePlus 001331
eMedicine med/2308 emerg/613
MeSH D014246

Trichomoniasis, sometimes referred to as "trich", is a common cause of vaginitis. It is a sexually transmitted disease, and is caused by the single-celled protozoan parasite Trichomonas vaginalis producing mechanical stress on host cells and then ingesting cell fragments after cell death.[1] Trichomoniasis is primarily an infection of the urogenital tract; the most common site of infection is the urethra and the vagina in women.

Signs and symptoms[edit]

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.[2] In many cases, men may hold the parasite for some years without any signs.


Trichomoniasis is diagnosed by visually observing the trichomonads via a microscope. In women, the examiner collects the specimen during a pelvic examination by inserting a speculum into the vagina and then using a cotton-tipped applicator to collect the sample. The sample is then placed onto a microscopic slide and sent to a laboratory to be analyzed.

Trichomoniasis has been difficult to diagnose due to the poor sensitivity of the tests, and some sexual health specialists have speculated that the condition can probably be carried undetected in the vagina for years as a consequence.[3] In 2011, a study reported that nucleic acid testing was a more reliable test.[4]


Lifecycle of Trichomonas

The human genital tract is the only reservoir for this species. Trichomonas is transmitted through sexual or genital contact.[5]

Genetic sequence[edit]

A draft sequence of the Trichomonas genome was published on January 12, 2007 in the journal Science confirming that the genome has at least 26,000 genes, a similar number to the human genome. An additional ~35,000 unconfirmed genes, including thousands that are part of potential transposable elements, brings the gene content to well over 60,000.[6]


Use of male condoms may help prevent the spread of trichomoniasis,[7] 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.[8]


Treatment for both pregnant and non-pregnant patients usually utilizes metronidazole (Flagyl),[9] but with caution especially in early stages of pregnancy[10] 2000 mg by mouth once. Sexual partners, even if asymptomatic, should be treated concurrently.[8]

Although both men and women are susceptible to suffer the infection, it is suspected that more than one half of men who are infected will naturally expel the parasite within 14 days,[11] while in women it will persist unless treated.


Research has shown a link between trichomoniasis and two serious sequelae. Data suggest that:

  • Trichomoniasis is associated with increased risk of transmission of HIV.
  • Trichomoniasis may cause a woman to deliver a low-birth-weight or premature infant.
  • Trichomoniasis is also associated with increased chances of cervical cancer
  • Evidence implies that infection in males potentially raises the risks of prostate cancer development and spread due to inflammation.[12][13]

Additional research is needed to fully explore these relationships.


Globally trichomoniasis affects approximately 152 million people as of 2010 (2.2% of the population).[14] It is more common in women (2.7%) than males (1.4%).[14] The American Social Health Association estimates trichomoniasis affects 7.4 million previously unaffected Americans each year and is among the most frequently presenting new infection of the common sexually transmitted diseases.[15]


  1. ^ Midlej V., Benchimol M. (2010). "Trichomonas vaginalis kills and eats- evidence for phagocytic activity as a cytopathic effect". Parasitology 137 (1): 65–76. doi:10.1017/S0031182009991041. PMID 19723359. 
  2. ^ Trichomoniasis symptoms.
  3. ^ [1]. Can trichomoniasis be dormant? MedHelp
  4. ^ Andrea SB, Chapin KC (2011). "Comparison of Aptima Trichomonas vaginalis Transcription-Mediated Amplification Assay and BD Affirm VPIII for Detection of T. vaginalis in Symptomatic Women: Performance Parameters and Epidemiological Implications.". J Clin Microbiol 49 (3): 866–9. doi:10.1128/JCM.02367-10. PMC 3067695. PMID 21248097. Lay summary. 
  5. ^ "Trichomoniasis - CDC Fact Sheet". Retrieved 12 January 2011. 
  6. ^ Scientists crack the genome of the parasite causing trichomoniasis. Jan. 12, 2007.
  7. ^ Vaginitis/Trichomoniasis :Reduce your risk, American Social Health Association. Retrieved March 12, 2008.
  8. ^ a b Rob, Lukáš; Martan, Alois; Citterbart, Karel et al. (2008). Gynekologie (in Czech) (2nd ed.). Prague: Galen. p. 136. ISBN 978-80-7262-501-7. 
  9. ^ Vaginitis/Trichomoniasis :Treatment for trichomoniasis, American Social Health Association. Retrieved March 12, 2008.
  10. ^ Cudmore SL, Delgaty KL, Hayward-McClelland SF, Petrin DP, Garber GE (October 2004). "Treatment of infections caused by metronidazole-resistant Trichomonas vaginalis". Clin. Microbiol. Rev. 17 (4): 783–93, table of contents. doi:10.1128/CMR.17.4.783-793.2004. PMC 523556. PMID 15489348. 
  11. ^ Heather Feldman. Scientists fighting STD with research, education. 
  12. ^ Jennifer R. Stark et al (2009). Prospective Study of Trichomonas vaginalis Infection and Prostate Cancer Incidence and Mortality: Physicians' Health Study, Retrieved May 20 2014.
  13. ^ BBC (2014). Prostate cancer 'may be a sexually transmitted disease', Retrieved May 20 2014.
  14. ^ a b Vos, T (Dec 15, 2012). "Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010.". Lancet 380 (9859): 2163–96. doi:10.1016/S0140-6736(12)61729-2. PMID 23245607. 
  15. ^ Associated Press, Abstinence students still having sex, MSNBC, April 16, 2007. Retrieved March 12, 2008.

External links[edit]