Trichomoniasis

Trichomoniasis is a sexually transmitted disease (STD) caused by a parasite that is passed from one person to another through sexual contact or through contact with damp objects that contain the parasite. Also known as “trich” or “trick,” it does not pose a major health risk, but can be uncomfortable for those who are infected.

Trichomoniasis infects 7.4 million women and men every year, according to the U.S. Centers for Disease Control and Prevention (CDC). The illness is relatively rare in men and more common in women. In fact, trichomoniasis is the most common, curable STD in young women and affects about 5 to 10 percent of all women, according to the National Women’s Health Resource Center. In addition, some studies have found that up to 50 percent of women infected with other STDs are also infected with trichomoniasis.

A single-celled protozoan parasite called Trichomonas vaginalis causes trichomoniasis. This parasite has a tail resembling a whip that it uses to propel itself through vaginal and urethral mucus. The vagina is the most common site of infection in women, while the urethra is the most common site of infection in men. The parasite that causes trichomoniasis cannot survive in the mouth or rectum.

Women can develop trichomoniasis after sexual contact with infected men or women – e.g., through penis-to-vagina or vulva-to-vulva contact. Infection can also be spread through oral or possibly anal sex. In addition, a woman can become infected if her genitals come into contact with certain objects that contain the parasite. These objects include toilet seats, damp towels or washcloths and wet clothing, such as swimsuits.

Infection is most commonly transmitted during vaginal intercourse. Men usually contract the infection from sexual contact with an infected woman.

Trichomoniasis is considered one of the three main causes of vaginitis. However, many women with trichomoniasis do not experience the symptoms of vaginitis (e.g., burning sensation, discomfort during urination). However, even if no symptoms are present, people with trichomoniasis can still pass the disease on to others.

A trichomoniasis infection makes a person more vulnerable to other STDs, including the human immunodeficiency virus (HIV). A trichomoniasis infection stimulates the immune system, resulting in higher production of the immune system response cells that the HIV virus targets. In addition, women who have both HIV and trichomoniasis are more likely to infect their partners with HIV.

Prolonged infection in women also can cause changes in cervical surface tissues. Complications of trichomoniasis in men include prostatitis (inflammation of the prostate) or epididymitis (inflammation of the tubes that carry and store sperm).

Pregnant women who are infected with trichomoniasis may experience premature labor and delivery, and may give birth to babies who have low birth weight (less than 5 pounds). For this reason, it is important for pregnant women to inform their physician if they are experiencing symptoms of infection.

About one-third to one-half of women infected with trichomoniasis experience no symptoms, according to the National Women’s Health Resource Center. However, other women do experience symptoms, usually between 5 and 28 days after exposure.

Most men infected with trichomoniasis do not experience symptoms. In some cases, men may have urethritis (inflammation of the urethra), itching of the urethra, dysuria (difficulty or pain during urination) or a slight discharge from the penis. Some men also may experience a slight burning following urination or ejaculation.

A man’s symptoms may disappear after about a week or so, even if he has not received treatment. However, men whose trichomoniasis infections are not treated can continue to infect others until they receive treatment.

Women and men who have any of the symptoms associated with trichomoniasis are urged to refrain from having sexual relations until their condition is diagnosed and treated.

To diagnose trichomoniasis, a physician will compile a patient’s medical history and perform a complete physical examination. Female patients will undergo a pelvic examination, during which the physician will open the walls of the vagina and look for small red sores inside the vagina or on the cervix.

A sample of vaginal fluid will be obtained and examined under a microscope to determine the presence of parasites. Additional tests that may be performed include a vaginal culture or DNA test. Physicians frequently also perform tests for other sexually transmitted diseases (STDs) such as gonorrhea and chlamydia, which may accompany trichomoniasis. A Pap smear may be performed to look for changes in cervical surface tissues that are sometimes associated with a prolonged trichomoniasis infection.

Trichomoniasis is often more difficult to diagnose in male patients. Special culture techniques may be necessary to make a definitive diagnosis. Male sexual partners of females infected with trichomoniasis are often assumed to be infected as well.

In most cases, trichomoniasis is treated with a single oral dose of the prescription drug metronidazole which is used to treat bacterial, fungal and parasitic infections. If this fails to cure the infection, a longer treatment regimen of three to five days may be required.

In 2004, the U.S. Food and Drug Administration (FDA) approved another drug, tinidazole, to treat trichomoniasis and other protozoa infections. This drug is now being used in patients who fail to respond to treatment with metronidazole.

Unlike some sexually transmitted diseases, trichomoniasis has not developed strains that are resistant to medications, so the prognosis for patients who take these medications is excellent. In about 5 percent of cases, women do not respond to standard treatments. In such situations, an allergy to the medication may be to blame for the lack of success.

Patients who are allergic to metronidazole or tinidazole may receive a prescription for a topical medication called paromomycin. While topical medications may reduce symptoms, they usually are less effective than metronidazole or tinidazole and may not cure the infection.

The U.S. Centers for Disease Control and Prevention recommends that both partners receive treatment if one partner has been diagnosed with trichomoniasis. This will ensure that any traces of the parasite in either partner are eliminated and will not be further transmitted. Patients should refrain from sexual activity while they are being treated or until their symptoms subside.

Women should not take medications commonly used for this condition during the first three months of pregnancy, according to the FDA. However, after the first trimester, metronidazole or tinidazole may be taken if necessary. The National Women’s Health Information Center suggests treating pregnant women who have symptoms and not treating those who have no symptoms.

There is no medication in the United States that may help prevent trichomoniasis. In Europe, however, a vaccine for trichomoniasis has been marketed but has proven to be largely ineffective.

Having contracted trichomoniasis does not provide immunity against future infection. People who are successfully treated for trichomoniasis can become infected again if they are exposed to the parasite that causes the condition.

Certain preventive measures may help to reduce the risk of contracting trichomoniasis.