Vaginal infections are often accompanied by vaginitis, which is an inflammation of the vagina characterized by discharge, irritation, and/or itching. The cause of vaginitis cannot be adequately determined solely on the basis of symptoms or a physical examination. Laboratory tests allowing microscopic evaluation of vaginal fluid are required for a correct diagnosis. A variety of effective drugs are available for treating vaginal infections and accompanying vaginitis.

Trichomoniasis, sometimes referred to as "trich", is a common STD that affects 2 to 3 million Americans yearly. It is caused by a single-celled protozoan parasite called Trichomonas vaginalis. Trichomoniasis is primarily an infection of the urogenital tract; the urethra is the most common site of infection in men, and the vagina is the most common site of infection in women.


Trichomoniasis, like many other STDs, often occurs without any symptoms. When symptoms occur, they usually appear within 4 to 20 days of exposure, although symptoms can appear years after infection. The symptoms in women include a heavy, yellow-green or gray vaginal discharge, discomfort during intercourse, vaginal odor, and painful urination. Irritation and itching of the female genital area, and on rare occasions, lower abdominal pain also can be present. The symptoms in men include a thin, whitish discharge from the penis and painful or difficult urination. However, most men do not experience any symptoms.


Trichomoniasis is usually diagnosed in women by examining vaginal fluid under the microscope for evidence of the parasite; in some cases it can be detected on a Pap smear. Because only small numbers of parasites may be present during infection in a male, microscopic examination of discharge from the penis often does not reveal the presence of parasites. However, a sample of fluid from the penis may be taken from which the parasite can be grown in culture in the laboratory. Cultures may be required to establish the diagnosis in women who have no symptoms but are at high risk of infection. Cultures can also confirm the diagnosis in symptomatic women whose microscopic examinations are negative.


Although symptoms of trichomoniasis in men may disappear within a few weeks without treatment, men can transmit the disease to their sex partners even when symptoms are not present. Therefore, it is preferable to treat both partners to eliminate the parasite. Metronidazole is the drug used to treat trichomoniasis. It is administered in a single dose. People taking this drug should not drink alcohol; mixing the two substances can cause severe nausea and vomiting.


Although previously trichomoniasis was not thought to result in any important complications, recent studies have linked it to two serious sequelae. Data now suggest that trichomoniasis may increase the risk of transmission of human immunodeficiency virus (HIV), the virus that causes AIDS, and may cause delivery of low-birth-weight or premature infants. Additional research is needed to fully explore these relationships.


Condoms and diaphragms may be helpful in preventing the spread of trichomoniasis. Although there is some laboratory evidence that spermicides can kill STD organisms, scientists are still evaluating the usefulness of spermicides in preventing STDs. Some studies have found that frequent use of spermicides (more than three times a week) may cause vaginal inflammation.


Although most vaginal infections in women are due to bacterial vaginosis, trichomoniasis, and vulvovaginal candidiasis, it is clear that there are other causes. These causes may include allergic and irritative factors or other STDs.

Noninfectious allergic symptoms can be caused by spermicides, vaginal hygiene products, detergents, and fabric softeners. Cervical infections are also often associated with abnormal vaginal discharge, but these infections can be distinguished from true vaginal infections by appropriate tests. Finally, in uninfected women, vaginal discharge may be present during ovulation and may become so heavy that it raises concern.

In an effort to control vaginal infections, research is under way to determine the factors that promote the growth and disease-causing potential of vaginal microbes. No longer considered merely a benign annoyance, vaginitis is the object of serious investigation as scientists attempt to clarify its role in such conditions as pelvic inflammatory disease and pregnancy-related complications.

Prepared by: Office of Communications National Institute of Allergy and Infectious Diseases National Institutes of Health, Bethesda, Maryland 20892