Trichomoniasis - Symptoms and Treatment

Trichomoniasis is a sexually transmitted disease caused by the parasite Trichomonas vaginalis.

Trichomoniasis is a major cause of vaginitis and vaginal discharge for women, but is often an asymptomatic infection in men. In this paper we address the modes of transmission, symptoms, diagnosis and treatment of Trichomonas vaginalis.



Trichomoniasis is caused by unicellular protozoon Trichomonas vaginalis which can be seen in the image. Trichomoniasis is a major curable STD in the world, affecting approximately 170 million people every year.

The transmission is through sex and, oddly enough, occurs only through sex between woman and man or between woman and woman. Transmission of Trichomonas is rare among men, not known why. The sexual route is virtually the only form of transmission, so it is uncommon to get contamination through clothing, towels or other fomites.

The Trichomonas vaginalis is a parasite that infects only humans, normally lives in the vagina or urethra, but can also be found in other parts of the genitourinary system. The protozoan causes lesions of the vaginal epithelium leading to formation of microscopic ulcers that increase the risk of contamination by other STDs, such as HIV, HPV, herpes, gonorrhea and chlamydia.

The incubation period, i.e. the time between infection and the onset of the symptoms, usually varies between 4 and 28 days, but many people can be asymptomatic carriers of the parasite for longer periods. Some women have the Trichomonas for months before symptoms occur, making it very difficult to define the date on which the contamination occurred.


Trichomoniasis in men

The infection with Trichomonas vaginalis is usually asymptomatic and transient in men, improving spontaneously in many cases. The man is usually an asymptomatic carrier of the parasite. When there are symptoms, the most common framework is urethritis (inflammation of the urethra) leading to pain urinating and purulent urethral discharge. An unusual but possible complication is infection of the prostate gland by Trichomonas, leading to prostatitis.

Trichomoniasis in women

In females Trichomonas vaginalis infection can also be asymptomatic, but at least 2/3 of infected women have symptoms. The framework is the most commonly vaginitis, inflammation of the vagina that leads to runny yellow-green foul smelling associated with dysuria (pain passing urine), dyspareunia (pain during intercourse) and vaginal pruritus (itching).

If untreated Trichomoniasis is risk factor for infertility and cervical cancer. In pregnant women the infection is associated with preterm delivery.


The clinical picture of vaginitis only suggests the most likely cause, it is not possible to establish the diagnosis without further investigation. To confirm the presence of Trichomonas vaginalis gynecologist performs a gynecological examination, usually detects a vagina ignited with small ulcers. During the examination a sample of vaginal secretion is collected for studying under the microscope. In up to 70% of cases it is possible to identify the protozoan moving in secretions.

If the clinical and gynecological examination are very suggestive, but microscopic examination is negative, it is possible to make a culture of secretion, the result of which is usually ready between 3 to 7 days. The PCR (DNA) can also be used, it is more expensive, but presents results faster and more safely.

The Pap test can also detect Trichomonas, but its sensitivity is low and has a high false positive rate.


Trichomoniasis treatment
Trichomoniasis treatment
The Metronidazole and Tinidazole are two treatment options for trichomoniasis. The cure rate with these antibiotics is higher than 90% and no other drug has such effectiveness. The schedule shown consists of two grams of metronidazole or tinidazole orally (4 tablets of 500mg) in a single dose.

The consumption of alcohol is strictly prohibited in those being treated with one of two drugs. You must wait at least 3 days due to risk of serious backlash.

It is important to avoid sex for a week when under treatment and (a) partner(s) should also be treated, even if asymptomatic to prevent reinfection. About 70% of infected patients´┐Ż partners are also infected by the parasite.

As the success rate is very high, if symptoms resolve a patient does not need to repeat tests to confirm healing.

Metronidazole does not treat the other causes of vaginitis, such as gonorrhea and candidiasis. So avoid self medication and call your gynecologist if you have any problems.


To reduce the risk of contamination by Trichomonas:
  • Always use a condom during sex
  • Avoid having multiple partners
  • Avoid relationships with people still contaminated and untreated
  • If you have any problems, avoid sex until be seen by your gynecologist

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