Trichomonas Infection

Wet mount micrograph of T. vaginalis (arrows). Source: CDC.

Signs and Symptoms

Although some infected women have minor or no symptoms, many do have symptoms, which usually appear within 5 to 28 days after they come in contact with the parasite. The symptoms in women include

• Heavy, yellow-green or gray vaginal discharge
• Pain or discomfort during sex
• Vaginal odor
• Painful urination

Women also may have irritation and itching of the genital area and, on rare occasions, lower abdominal pain.

Most infected men do not have symptoms. If they do, the symptoms include a thin, whitish discharge from the penis and painful or difficult urination and ejaculation.

The time between exposure and development of symptoms (incubation period) is usually 4-28 days. The onset of symptoms such as vaginal or vulval irritation and discharge is often sudden and occurs during or after menstruation as a result of the increased vaginal acidity.

Cause

This is an illustration of the life cycle of Trichomonas vaginalis, the causal agent of Trichomoniasis. Source: CDC/Alexander J. da Silva, PhD/Melanie Moser

Trichomoniasis is caused by a single-celled parasite called Trichomonas vaginalis. T. vaginalis is a microscopic parasite found worldwide. Trichomoniasis is primarily an infection of the urogenital tract. The vagina is the most common place for infection in women, and the urethra (urine canal) is the most common place for infection in men.

Diagnosis

When women are infected with trichomoniasis, a pelvic examination usually reveals red sores on the cervix (opening to the womb) or inside the vagina. To confirm the diagnosis, fluid samples from the vagina or penis are used in laboratory tests. Diagnosis is most commonly made by viewing the parasite under a microscope which can be done while the patient is in the clinic. Culturing for the parasite is the most accurate way to diagnose trichomonas infection, but results may take 3 to 7 days.

Treatment

In most men and women, the use of metronidazole, an antibiotic/antiparasitic drug, is curative. This drug can be given by mouth as a single dose. It is very important that sexual partners of the person with trichomonas be treated as well, even if they do not have symptoms.

The disease can recur, either because of re-infection from a sexual partner, or because the initial treatment was inadequate. In some of these cases, higher doses of metronidazole will need to be used.

There have been rare reports of T. vaginalis that is resistant to metronidazole. An alternate drug, tinidazole, can be used, or in some, re-treatment with high dose metronidazole for a longer period of time can be effective.

While being treated for trichomoniasis, people should not engage in sexual intercourse, and if taking metronidazole or tinidazole, alcohol should be avoided for at least 24 hours after metronidazole is stopped, or 72 hours for tinidazole.

People who have trichomoniasis should always be screen for other sexually transmitted illnesses such as HIV, non-gonococcal urethritis and Chlamydia trachomatis.^[1]

Prevention

The surest way to avoid getting trichomoniasis is to abstain from sexual contact, or to be in a long-term mutually monogamous relationship with a partner who has been tested and is not infected. Using a latex male condom consistently and correctly during sex may help prevent the spread of trichomoniasis. The CDC recommends the following to prevent the spread of trichomoniasis:

• 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.

How is trichomoniasis spread?

Trichomoniasis is transmitted through sexual intercourse with an infected partner. Infection is more common in women who have had multiple sexual partners.

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

Although rare, babies born to infected mothers may catch T. vaginalis during delivery.^[2] Infants may develop fever; girls may develop a vaginal discharge. Children should be treated if diagnosed.

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. If infection is found in a teenager, this may indicate sexual activity or sexual abuse. An evaluation for other STDs is also recommended.

Related Problems

Complications

Research has shown a link between trichomoniasis and two serious complications.

• Scientific studies suggest that trichomoniasis is associated with at least a 3- to 5-fold increased risk of HIV transmission.^[3]
• Trichomoniasis may cause a woman to deliver a premature or low-birth-weight baby.
• Rarely, T. vaginalis may spread to the prostate gland, or cause epididymitis in men.

Research

To control vaginitis, research is under way to determine the factors that promote the growth and disease-causing potential of vaginal microbes. This information could help improve efforts to treat and prevent vaginitis. No longer considered merely a harmless annoyance, vaginitis is the object of serious studies as scientists try to clarify its role in such conditions as pelvic inflammatory disease and pregnancy-related complications.

Researchers have completed sequencing the genetic code of Trichomonas vaginalis. Scientists are beginning to understand its biology and to find new and innovative ways to prevent the disease it causes. Trichomonas vaginalis is also of particular interest to medical researchers because of its role in HIV transmission, infant morbidity, and the predisposition to cervical cancer. ^[4]

Epidemiology

It has been estimated that 7.4 million new cases of trichomoniasis occur each year in men and women in the United States. The infection has been found in 9% to 22% of women attending inner-city clinics. The occurrence of the disease is highest in women with multiple sex partners and in groups with high rates of other STDs.

T. vaginalis can be found in 66% to 100% of female partners of infected men, and in 22% to 80% of men whose female sex partner is infected.

The organism may be one of the most important cofactors in helping the spread of HIV, particularly in African American communities in the Unites States.^[5]

References

1. ↑ Reynolds M, Wilson J. Is Trichomonas vaginalis still a marker for other sexually transmitted infections in women? Int J STD AIDS. 1996 Mar-Apr;7(2):131-2. Abstract
2. ↑ Danesh IS, Stephen JM, Gorbach J. Neonatal Trichomonas vaginalis infection. J Emerg Med. 1995 Jan-Feb;13(1):51-4. Abstract
3. ↑ Laga M, Manoka A, Kivuvu M, et al. Non-ulcerative sexually transmitted diseases as risk factors for HIV-1 transmission in women: results from a cohort study. AIDS. 1993 Jan;7(1):95-102. Abstract
4. ↑ JM Carlton, RP Hirt, JC Silva, AL Delcher, M Schatz, Q Zhao et al. Draft genome sequence of the sexually transmitted pathogen Trichomonas vaginalis. 2007 Science 315 (5809), 207. | Abstract | Full Text | Press Release
5. ↑ Sorvillo F, Smith L, Kerndt P, Ash L. Trichomonas vaginalis, HIV, and African-Americans. Emerg Infect Dis. 2001 Nov-Dec;7(6):927-32. Abstract | Full Text

External Links

National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention

CDC: Sexually Transmitted Disease Information