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Trichomonas Infection


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What is Trichomonas infection?

Trichomonas vaginalis is a microscopic parasite that infects people throughout the world. Infection with Trichomonas is called trichomoniasis (trick-oh-moe-nye-uh-sis). Trichomoniasis is one of the most common sexually transmitted diseases, mainly causing symptoms in sexually active women. In North America, it is estimated that more than 8 million new cases are reported yearly.

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How is trichomoniasis spread?

Trichomoniasis is spread through sexual activity. Infection is more common in persons who have had multiple sexual partners.

A common misbelief is that infection can be spread by a toilet seat; this isn't likely, because the parasite cannot live long in the environment or on objects.

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What are the signs and symptoms of infection?


Signs and symptoms of infection range from having no symptoms (asymptomatic) to very symptomatic. Typical symptoms include foul smelling or frothy green discharge from the vagina, vaginal itching or redness. Other symptoms can include painful sexual intercourse, lower abdominal discomfort, and the urge to urinate.


Most men with this infection do not have symptoms. When symptoms are present, they most commonly include discharge from the urethra, the urge to urinate, and a burning sensation with urination.

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How long after infection do symptoms occur?

The normal incubation period is 4-28 days. The onset of symptoms such as vaginal or vulval pruritus and discharge is often sudden and occurs during or after menstruation, perhaps as a result of changes in vaginal acidity or homone levels.

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What should I do if I think I have trichomoniasis?

See your health care provider who can test you for infection.

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How is infection diagnosed?


Your health care provider will perform a pelvic exam to collect vaginal samples for examination. Diagnosis is most commonly made by viewing the parasite under a microscope. Culturing for the parasite is another common way to diagnose infection; results may take 3-7 days. In some clinics, detection of parasite DNA or antigens is also used. On occasion, the presence of Trichomonas parasites can be detected in a PAP smear. However, suspected infection detected by a PAP smear should be confirmed by more specific diagnostic methods.


Diagnosis is made by collecting specimens from the urethra or detecting parasite DNA in the urine.

No diagnostic test is 100% accurate; mistakes can be made. Your health care provider may order additional testing to confirm the diagnosis.

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I have trichomoniasis and am pregnant; can I spread infection to my baby?

Yes, but this is rare. Babies born to infected mothers may contract infection during delivery. Infants may develop fever; girls may develop vaginal discharge. Children should be treated if diagnosed. See your health care provider about treatment of trichomoniasis during pregnancy.

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How can a child get trichomoniasis?

Infants: If an infant is infected, it is possible that the mother spread infection during childbirth. The mother should be checked for infection.

Young children: Because trichomoniasis is an STD, infection in a young child may indicate sexual abuse. If sexual abuse is suspected, an evaluation for other STDs is recommended.

Teenagers: Because trichomoniasis is an STD, infection in a teenager may indicate sexual activity or sexual abuse. An evaluation for other STDs is recommended.

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Is infection treatable?

Yes. Your doctor will prescribe an antibiotic for you and all sexual partners you have had since becoming infected. If all current sexual partners are not treated, it is possible to become reinfected during subsequent sexual activity. Infants and children who are infected should be treated.

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Treatment failed, is there another recommendation?

Yes. However, you may be treated with the same drug, for a longer time and at a higher dose. Your doctor may prescribe more than one drug to treat you. All sexual partners should be treated at the same time. Use a latex condom or avoid having sexual intercourse to prevent reinfection during treatment. Lastly, you may have your health care provider contact the CDC for isolate resistance testing and treatment recommendations.

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Can risk of infection be reduced?

Yes. Follow these guidelines.

  • Abstain from sexual intercourse; or,
  • Use a latex condom properly, every time you have sexual intercourse, with every partner.
  • Limit your sexual partners. The more sex partners you have, the greater your risk of encountering someone who has this or other STDs.
  • If you are infected, your sexual partner(s) should be treated. This will prevent you from getting reinfected.

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Once I am infected, am I immune?

No. You can get infected again.

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This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the disease described above or think that you may have a parasitic infection, consult a health care provider.



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This page last reviewed September 3, 2008

Centers for Disease Control and Prevention
National Center for Zoonotic, Vector-Borne, and Enteric Diseases
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