TRICHOMONIASIS – Symptoms, Transmission And Treatment


In this article we will address the following points about trichomoniasis:

  • Transmission.
  • Signs and symptoms.
  • Diagnosis.
  • Treatment.
  • Prevention.


Trichomoniasis (“trich”) is a sexually transmitted disease caused by the protozoan Trichomonas vaginalis. It is the most common non-viral sexually transmitted disease (STD) worldwide, affecting about 170 million people. In the United States, an estimated 3.7 million people is infected.

In women, trichomoniasis is a major cause of vaginitis (infection of the vagina), leading to complaints such as foul-smelling vaginal discharge, genital itching and painful urination. On the other hand, in men, the infection is often asymptomatic.

How do you get trichomoniasis?

Trichomoniasis is virtually always sexually transmitted. Although survival on fomites has been reported, this route of transmission has not been proven. Thus transmission through towels, washcloths and clothing is possible, but very unlikely. Trichomonas vaginalis is also not spread through physical contact, such as hugging, kissing, sharing dishes, or sitting on a toilet seat.

Interestingly, transmission occurs only through sex between woman and man or between woman and woman. Transmission of T.vaginalis among men is uncommon. During sex, the parasite usually spreads from the penis to the vagina, from the vagina to the penis or from the vagina to another vagina. Contamination of other parts of the body, such as the hands, mouth and anus is rare.

Trichomonas vaginalis is a parasite that only infects humans. It usually lives inside the genitourinary system. The protozoan causes lesions of the vaginal epithelium, leading to the formation of microscopic ulcers that increase the risk of contamination by other STDs, including HIV, HPV, genital herpes, gonorrhea and chlamydia.

The incubation period, i.e. the time between contamination and the onset of symptoms generally ranges from 4 to 28 days. However, many people can be asymptomatic carriers of the parasite for long periods. Some women have T.vaginalis for months before symptoms appear, making it very difficult to define the date on which the contamination occurred.

Infected people without symptoms can still pass the protozoan on to others.


Trichomoniasis in men

In men, trichomoniasis is usually asymptomatic and transient, with spontaneous healing in many cases. However, in some men, untreated infection can persist for months.

When there are symptoms, the most common are due to urethritis (inflammation of the urethra), such as pain to urinate, itching or irritation inside the penis and purulent urethral discharge. An unusual, but possible, complication is the infection of the prostate by the T. Vaginalis, leading to prostatitis.

Trichomoniasis in women

In women, trichomoniasis may also be asymptomatic, but at least 2/3 of infected women have symptoms.

Women with symptomatic trichomoniasis may notice: itching or soreness of the vagina, painful urination, dyspareunia (pain during sexual intercourse), and a white, yellowish or greenish vaginal discharge with an unpleasant smell.

Without treatment, the infection can last for months or even years, and is a risk factor for infertility, chronic pelvic pain and cervical cancer.

Pregnant women

T. vaginalis infection during pregnancy is associated with many complications, including premature rupture of the membranes, preterm delivery, and delivery of a low birth weight infant.


It is not possible to diagnose trichomoniasis based solely on the symptoms. Laboratory tests are necessary to establish the diagnosis.

To confirm the presence of Trichomonas vaginalis, the gynecologist performs a gynecological examination, which normally detects an inflamed vagina and small ulcers. During the examination a sample of vaginal secretion is collected to be studied under a microscope. In men, the urine or urethral discharge can be used.

Growing a culture used to be the way to diagnose trichomoniasis, but despite being relatively cheap, its sensitivity is still somewhat low (70-80%). Newer tests that look for T. vaginalis DNA (NAAT) are more costly but are highly sensitive (more than 90%).

The Pap smear test may also detect Trichomonas vaginalis, but its sensitivity is low, missing about 50% of the cases. It also has a high false positive rate (positive test in uncontaminated people).


Metronidazole and Tinidazole are the only drugs that provide curative therapy for trichomoniasis. The cure rate with these antibiotics is over 90%. No other drug has such efficacy.

The standard treatment regimen consists of 2 grams of metronidazole or tinidazole (4 tablets of 500 mg) taken by mouth in a single dose.

Pregnant and breastfeeding women can be treated with metronidazole.

Warning: alcohol consumption is strictly prohibited during the treatment with metronidazole or tinidazole. It is necessary to wait for at least 3 days due to the risk of serious reactions.

About 70% of the partners are also infected by the parasite. So, to avoid reinfection, your partner should also be treated, even if he or she is asymptomatic. You will have to wait 7 days after you and your partner have been treated to have sex again.

The symptoms should go away after a week. If they continue longer, talk to your doctor about getting retested and retreated. On the other hand, since the success rate is very high, if the symptoms disappear you do not need to repeat the tests to confirm the cure.

Metronidazole and tinidazole are not effective against other causes of vaginitis, such as gonorrhea, chlamydia and candidiasis. So, if you have vaginal discharge, avoid self-medication and look for your gynecologist to be properly tested and treated.

To know more about the causes of vaginal discharge, read: TYPES OF VAGINAL DISCHARGE: Brown, Yellow, White, etc


To reduce the risk of trich contamination:

  • Always use condoms during sex.
  • Avoid having multiple partners.
  • If you have vaginal or urethral discharge, avoid sexual intercourse until you are treated.
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