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Trichomoniasis refers to an infection of the genital and urinary tract. It is the most common sexually transmitted disease, affecting about 120 million women worldwide each year.


Trichomoniasis is caused by a protozoan (the smallest, single-celled members of the animal kingdom). Trichomonas vaginalis is passed almost 100% of the time through sexual contact. Trichomoniasis is primarily an infection of women's vaginal and urinary tracts. A woman is most susceptible to infection just after having completed her menstrual period. Men may carry the organism unknowingly, since infection in men may cause mild or no symptoms.

Causes and symptoms

Because trichomoniasis is a sexually transmitted disease, it occurs more often in individuals who have multiple sexual partners. The protozoan is passed to an individual by contact within the body fluids of an infected sexual partner. It often occurs simultaneously with other sexually transmitted diseases, especially gonorrhea.
In women, the symptoms of trichomoniasis include an unpleasant vaginal odor, and a heavy, frothy, yellow discharge from the vagina. The genital area (vulva) is often very itchy, and there is frequently pain with urination or with sexual intercourse. The labia (lips) of the vagina, the vagina itself, and the cervix (the narrowed, lowest segment of the uterus which extends into the upper part of the vagina) will be bright red and irritated.
In men, there are usually no symptoms at all. Occasionally, a man will notice a small amount of yellowish discharge from his penis, usually first thing in the morning. There may be some inflammation of the urethra, or urethritis, which produces mild discomfort while urinating.
The use of antibiotics is a contributing factor to recurrent trichomoniasis in some women because antibiotics affect the balance of bacteria in the vagina, allowing such organisms as T. vaginalis to multiply more rapidly.


Diagnosis is easily made by taking a sample of the discharge from the women's vagina, or from the opening of the man's penis. The sample is put on a slide, and viewed under a microscope. The protozoa, which are able to move about, are easily viewed.
Trichomoniasis tends to be underdiagnosed in men because of the relative mildness of symptoms in men and insufficiently sensitive diagnostic tests. The recent introduction of DNA amplification, however, indicates that the incidence of trichomoniasis in men is much higher than was previously thought.


The usual treatment is a single large dose of metronidazole, or split doses over the course of a week. Sexual partners of an infected individual must all be treated, to prevent the infection being passed back and forth.
Women who are taking antibiotics for other illnesses should speak to their health care provider about the possibile effects of the medication(s) on the balance of organisms in their vagina.
As of late 2003, the number of cases of metronidazole-resistant trichomoniasis appears to be increasing rapidly. Some success has been reported with the broad-spectrum anti-parasitic drug nitazoxanide, but further research needs to be done. A group of researchers in Thailand is currently investigating the effectiveness of a group of drugs known as bisquaternary quinolinium salt compounds in treating trichomoniasis.

Key terms

Metronidazole — An anti-infective agent regarded as the best available drug for treating trichomoniasis. It is sold under the trade names Flagyl and MetroGel.
Protozoan — A one-celled organism belonging to the simplest phylum of the animal kingdom. Trichomoniasis is caused by a protozoan.
Urethritis — Inflammation of the urethra, which is the canal that carries urine from the bladder to the outside of the body.

Alternative treatment

Cure of trichomoniasis may be difficult to achieve with alternative treatments. Some practitioners suggest eliminating sweets and carbohydrates from the diet and supplementing with antioxidants, including vitamins A, C, and E, and zinc. Naturopaths may recommend treatment with two douches (a wash used inside the vagina), alternating one in the morning and one at bedtime. One douche contains the herbs calendula (Calendula officinalis), goldenseal (Hydrastis canadensis), and echinacea (Echinacea spp.); the other douche contains plain yogurt. The herbal douche helps to kill the protozoa, while the yogurt reestablishes healthy flora in the vagina. Another herbal remedy that is sometimes used is tea tree oil. Acidifying the vagina by douching with boric acid or vinegar may also be useful.


Prognosis is excellent with appropriate treatment of the patient and all sexual partners. Without treatment, the infection can smolder on for a very long time, and can be passed to all sexual partners.


All sexually transmitted diseases can be prevented by using adequate protection during sexual intercourse. Effective forms of protection include male and female condoms.



Pelletier, Kenneth R., MD. The Best Alternative Medicine, Part II, "CAM Therapies for Specific Conditions: Vaginitis." New York: Simon & Schuster, 2002.


Chavalitshewinkoon-Petmitr, P., M. Ramdja, S. Kajorndechakiat, et al. "In vitro Susceptibility of Trichomonas vaginalis to AT-Specific Minor Groove Binding Drugs" Journal of Antimicrobial Chemotherapy 52 (August 2003): 287-289.
Ching, Susanne, and Phuong H. Nguyen. "Vaginitis." eMedicine April 5, 2002.
Dunne, R. L., L. A. Dunn, P. Upcroft, et al. "Drug Resistance in the Sexually Transmitted Protozoan Trichomonas vaginalis." Cell Research 13 (August 2003): 239-249.
Pirotta, M. V., J. M. Gunn, and P. Chondros. "'Not Thrush Again!' Women's Experience of Post-Antibiotic Vulvovaginitis." Medical Journal of Australia 179 (July 7, 2003): 47-49.
Schwebke, J. R., and E. W. Hook, 3rd. "High Rates of Trichomonas vaginalis Among Men Attending a Sexually Transmitted Diseases Clinic: Implications for Screening and Urethritis Management." Journal of Infectious Diseases 188 (August 1, 2003): 465-468.


Centers for Disease Control and Prevention (CDC). "Fact Sheet: Trichomonas Infection."
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


a sexually transmitted disease caused by Trichomonas vaginalis. In females, vaginal or urethral infections may be asymptomatic or may produce itching or burning, dysuria, and green, yellow, or white vaginal or urethral discharge. Males can be asymptomatic carriers or they can develop urethritis, enlargement of the prostate, and epididymitis from the infection. Trichomonacides such as metronidazole (Flagyl) are used in treatment. Both symptomatic patients and their sexual partners must be treated to avoid reinfection.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


Disease caused by infection with a species of protozoon of the genus Trichomonas or related genera.
Farlex Partner Medical Dictionary © Farlex 2012


n. pl. trichomonia·ses (-sēz′)
1. A vaginal infection caused by a trichomonad (Trichomonas vaginalis) and marked by vaginal discharge and itching.
2. An infection caused by trichomonads, as a disease of cattle that commonly results in infertility or abortion in infected cows.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


STD A urogenital infection by Trichomonas vaginalis transmitted through sexual contact but also contact with contaminated surfaces–eg, wet wash cloths, toilet seats; ♂ only contract it from infected ♀ Clinical In ♂, infection is usually banal, and clears spontaneously; some ♂ experience urethral itching or discharge, burning after urination or ejaculation, or develop prostatitis or epididymitis; ♀ have voluminous fizzy, stinky, purulent, and generally nasty vaginal discharge, itching on labia and inner thighs and labial swelling; over  half ♀ with gonorrhea also have trichomonas Diagnosis Pap smear, culture Management Metronidazole, econazole, tinidazole. See Sexually transmitted disease.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


Disease caused by infection with a protozoan of the genus Trichomonas; often used to designate trichomoniasis vaginitis.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


Infection with the single-celled, flagellated PROTOZOON Trichomonas vaginalis , most commonly in the vagina but sometimes in the URETHRA or the PROSTATE gland in men. Trichomoniasis causes irritation, burning and itching and a frothy, yellowish, offensive discharge. Treatment is with the drug metronidazole (Flagyl). Both partners must be treated.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
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