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Micrograph showing a positive result for trichomoniasis. A trichomonas organism is seen on the top-right of the image.
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. 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
Typically, only women experience symptoms associated with Trichomonas infection. Symptoms include inflammation of the cervix (cervicitis), urethra (urethritis), and vagina (vaginitis) which produce an itching or burning sensation. Discomfort may increase during intercourse and urination. 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 in women within 5 to 28 days of exposure. In many cases, men may hold the parasite for some years without any signs (dormant). Some sexual health specialists have stated that the condition can probably be carried in the vagina for years, despite standard tests being negative. While symptoms are most common in women, some men may temporarily exhibit symptoms such as an irritation inside the penis, mild discharge or slight burning after urination or ejaculation.
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.
The human genital tract is the only reservoir for this species. Trichomonas is transmitted through sexual or genital contact.
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. 
Use of male condoms may help prevent the spread of trichomoniasis, 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.
Treatment for both pregnant and non-pregnant patients usually utilizes metronidazole (Flagyl), but with caution especially in early stages of pregnancy 2000 mg by mouth once. Sexual partners, even if asymptomatic, should be treated concurrently.
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, 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.
Additional research is needed to fully explore these relationships.
Globally trichomoniasis affects approximately 152 million people as of 2010 (2.2% of the population). It is more common in women (2.7%) than males (1.4%). 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.
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- eMedicine Health Trichomoniasis
- Trichomonas columbae video
- Can trichomoniasis be dormant?