Trichomoniasis, an infection caused by a protozoan organism called Trichomonas vaginalis (TV), is one of the most commonly occurring sexually transmitted infections (STI/STD) in the world. There are more than 200 million new cases of trichomoniasis around the world each year.1

Of these, about 5 million new infections occur in the United States each year 2 —more cases then are attributed to either chlamydia or herpes in a year.

TV affects about a fifth of all women in their reproductive years.3 It is most prevalent in African American women—as many as one quarter to one half have TV. TV has been found in 3% of college students attending a student health clinic and in 37% of commercial sex workers.4 TV rates in men at STD clinics range from 3 - 17%.5 TV causes about a fifth (20%) of the cases of nongonococcal urethritis (inflammation of urethra not caused by gonorrhea) in men.6

What Happens if I get TV?

50-75% of persons with TV have no symptoms.1
 
In men, inflammation of the urethra or mild discharge may occur, although most men with TV (85%) have no symptoms at all.1,2
 
Only one-fifth to one-half of infected women have symptoms. Typically there is a yellow-green vaginal discharge.  Red spots—visible in only few cases (10%)—are called “strawberry spots” or colpitis macularis and are highly specific for TV.3

In addition to the discharge, the infection may cause irritation, an unpleasant odor, and serious consequences if not treated. Abdominal pain may also occur in 12% of women due to severe vaginitis.

References:
1.1. Sorvillo F, Smith L, Krendt P, Ash L, et al. Trichomonas Vaginalis, HIV, and African-Americans. Emerg Infect Dis 2001;7(6):927-932.
2.2. Schwebke JR, Hook EW, III. High rates of Trichomonas Vaginalis among men attending a sexually transmitted diseases clinic: Implications for screening urethritis management. J Infect Dis. 2003;188(3):465-8.
3.3. Wendel KA, Erbelding EJ, Gaydos CA, Rompalo AM, et al. Use of urine polymerase chain reaction to define the prevalence and clinical presentation of Trichomonas Vaginalis in men attending STD clinic. Sex Transm Infect. 2003;79(2):151-3.
4.4. Kreiger JN, Alderete JF. Trichomonas Vaginalis and Trichomoniasis. In:  Holmes et al, eds. Sexually Transmitted Diseases. New York: McGraw-Hill. 1999.
What are the Long-Term Effects of TV?

In pregnant women, TV infection can cause premature rupture of membranes and preterm (early) delivery.1  Between 2-17% of female infants born to infected women develop vaginal infections.2  This is usually asymptomatic although vaginal discharge may sometimes occur.
 
Untreated infections in women may persist for 3-5 years.3

References:
1.1. Centers for Disease Control and Prevention. Trichomoniasis Fact Sheet. Updated 2003. Available at http://www.cdc.gov/std/Trichomonas/STDFact-Trichomoniasis.htm. Accessed April 3, 2004.
2.2. Kreiger JN, Alderete JF.  Trichomonas Vaginalis and Trichomoniasis. In:  Holmes et al, eds. Sexually Transmitted Diseases. New York: McGraw-Hill. 1999.
3. Golden MR. Sexually Transmitted Diseases. In:  Dale DC, ed.  Infectious Diseases: The clinical guide to diagnosis, treatment, and prevention. New York: WebMD. 2003.

How is TV Diagnosed and Treated?

Clinical signs are not very helpful in diagnosis. Most commonly used lab tests include the wet mount and pap smears to identify the typical TV organisms. These tests have an accuracy of only 50-70%.1 Culture techniques are also used to identify TV, although these are not available at all clinics.
 
TV is usually quite easily treated with a single dose of metronidazole. In clinical trials this regimen successfully treats most (90-95%) infections. Follow up of patients is recommended even after becoming asymptomatic.2 Metronidazole-resistant trichomoniasis has been widely reported and is hard to treat.3 There is a reported increase in the number of such cases and due to its role as a HIV cofactor some experts recommend improved surveillance of such cases of resistance.4 

The main danger of this STD is that is causes premature breaking of the amniotic sac and thus premature birth of babies whose mothers are infected.  This is, of course, a serious health threat for the baby.

References:
1.1. Sorvillo F, Smith L, Krendt P, Ash L, et al. Trichomonas Vaginalis, HIV, and African-Americans. Emerg Infect Dis 2001;7(6):927-932.
2.2. Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines -- 2002. MMWR [online] 2002;51(RR06);1-80. Available at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5106a1.htm. Accessed March 30, 2004.
3.3. Sobel JD, Nyirjesy P, Brown W. Tinidazole therapy for metronidazole-resistant vaginal trichomoniasis. Clinical Infectious Diseases. 2001;33:1341-1346.
4.4. Dunne RL, Dunn LA, Upcroft P, O’Donoghue PJ, Upcroft JA. Drug resistance in the sexually transmitted protozoan Trichomonas vaginalis. Cell Research. 2003;13(4):239-249.

[from The Medical Institute, www.medinstitute.org]