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Trichomoniasis

Last updated Dec. 24, 2018

Approved by: Krish Tangella MD, MBA, FCAP

Trichomoniasis is one of the most common sexually-transmitted disease (STD) caused by a small and single-celled protozoan parasite called Trichomonas vaginallis (or T. vaginallis).


What are the other Names for this Condition? (Also known as/Synonyms)

  • Trich
  • Trichomonas Vaginallis Infection

What is Trichomoniasis? (Definition/Background Information)

  • Trichomoniasis is one of the most common sexually-transmitted disease (STD) caused by a small and single-celled protozoan parasite called Trichomonas vaginallis (or T. vaginallis)
  • The infection is usually reported in males and females of reproductive age. However, females get diagnosed at a higher frequency owing to manifestation of symptoms, and subsequently seeking medical treatment
  • Women with the parasite may notice a foul-smelling discharge and vaginal itching. Some women, may not have any symptoms. Men, who contract Trichomoniasis, tend to be more asymptomatic than women, but may have symptoms of non-gonococcal urethritis (i.e., inflammation of the urethra not caused by gonorrhea)
  • Observation of a vaginal or penis swab under the microscope to identify the parasite is the main method of diagnosing Trichomoniasis
  • T. vaginallis infection may render the affected individuals more susceptible to other sexually-transmitted diseases and infections. Also, Trichomoniasis in pregnant women may cause complications including premature birth
  • However, the disease is curable and the prognosis is good for individuals with Trichomoniasis, when both the affected individual and his/her partner are treated with prescription antibiotics

Who gets Trichomoniasis? (Age and Sex Distribution)

  • Trichomoniasis is a common sexually transmitted disease affecting approximately 160 million individuals annually worldwide
  • Individuals of reproductive age in sexual relationships tend to get infected more frequently than individuals belonging to any other age group
  • A sizeable number of adolescent and young adults are being diagnosed with this infection as well. With increase in age, susceptibility to infection and invasion of T. vaginallis also increases
  • Both men and women are affected; although, more women seek medical attention than men, due to the presentation of significant symptoms
  • Non-Hispanic black females are 4 times more prone to getting infected than women of any other ethnic and racial descent

What are the Risk Factors for Trichomoniasis? (Predisposing Factors)

The risk factors for contracting Trichomoniasis may include:

  • Unprotected sexual intercourse
  • Improper use of condoms during intercourse 
  • Having more than one sexual partner (non-monogamous relationships)
  • Individuals belong to low income levels and poor socioeconomic status
  • Drug and alcohol use
  • Being sexually active
  • Douching (using a stream of water to clean the vagina, or as a contraceptive method)

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your health care provider.

What are the Causes of Trichomoniasis? (Etiology)

Infection with Trichomonas vaginallis parasite, which is a single-celled microscopic protozoan, causes Trichomoniasis.

  • The pathogen can be introduced to an uninfected individual through skin-to-skin contact, during unprotected or improperly-protected sexual intercourse with an infected partner
  • T. vaginallis adheres to the epithelial cells of the genital tract. Once it has invaded the host, the
    • Pathogen transforms from an oval to a flat shape, 
    • Which initiates the release of chemicals and toxins,
    • And, these toxins digest the host cells leading to their fragmentation

What are the Signs and Symptoms of Trichomoniasis?

The signs and symptoms of Trichomoniasis may vary in type and severity between the affected individuals. It also depends upon the gender type.

In women, the signs and symptoms may include:

  • A change in one’s normal vaginal discharge, which can be in the amount, thickness, or color of the discharge
  • Foul-smelling vaginal discharge
  • Vaginal itching, burning, stinging, and pain 
  • Burning sensation during urination 
  • Discomfort during sexual intercourse

In many cases of infection in men, Trichomoniasis may be asymptomatic and go unnoticed and undiagnosed. If symptoms are present, then these may include the following:

  • Burning sensation or itching in the penis
  • Stinging, itching, or irritation during urination
  • Burning sensation after ejaculation
  • Unusual discharge during urination or sexual intercourse

How is Trichomoniasis Diagnosed?

The diagnosis of Trichomoniasis is made based on the following tests and exams: 

  • A thorough physical and medical history examination by a healthcare professional 
  • Assessment of signs and symptoms
  • Microscopic observation of vaginal or penile swab: The sample of discharge is placed on a wet mount (type of microscope preparation) and observed for morphology and characteristics of the T. vaginallis, such as, oval shape, jerky movement, and rapidly-changing direction due to flagella on the parasite
  • Direct fluorescent antibody test to check for presence of the parasite
  • Culture of sample for further testing
  • Nucleic acid amplification methods to detect specific DNA sequences of the parasite

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Trichomoniasis?

Trichomoniasis may lead to complications such as the following:

  • Vaginitis or inflammation of the vagina
  • Premature delivery, low birth weight of baby, and transmission of infection to baby during birth, if a pregnant women contracts Trichomoniasis
  • Increased susceptibility to other STDs or STIs

How is Trichomoniasis Treated?

  • Trichomoniasis is treated with oral prescription antibiotics (such as metronidazole, tinidazole) for both partners in a sexual relationship
  • According to US Centers for Disease Control and Prevention (CDC), metronidazole and tinidazole are safe for pregnant women

It is important to note that alcohol should not be consumed for at least 24 hours, after taking the prescription antibiotic.

How can Trichomoniasis be Prevented?

Trichomoniasis may be preventable by considering the following factors:

  • Using latex condoms (properly) for sexual intercourse
  • Being in a monogamous relationship 
  • If sexually-active with multiple partners, then periodic testing for sexually-transmitted diseases/infections is advised
  • Ensuring that a partner has tested negative for STD/STIs, before engaging in a sexual activity
  • Seeking treatment for both partners of a sexual relationship, if one is diagnosed with the infection. Also, waiting 7-10 days after treatment to resume having sex, in order to avoid recurrence of infection

What Is the Prognosis of Trichomoniasis? (Outcomes/Resolutions)

  • The prognosis for Trichomoniasis is good with prompt treatment. Treatment of the condition using anti-parasite drugs can result in a high cure rate (between 80-100%)
  • However, the infection can recur. It has been reported that about 20% of sexually-active individuals get the infection within 3 months of treatment
  • Pregnant women with infection often have undesired pregnancy outcomes, and transmission to the newborn is a possibility

Additional and Relevant Useful Information for Trichomoniasis:

Approximately, over 3 million individuals contract Trichomoniasis every year in the United States.

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Sept. 6, 2017
Last updated: Dec. 24, 2018