Description

• Sexually transmitted urogenital infection caused by a pear-shaped, parasitic protozoan
• Causes vaginitis/urethritis in women, nongonococcal urethritis in men
• In pregnancy, increases risk of preterm labor, preterm premature rupture of membranes, small for gestational age infant, and possibly stillbirth
• Synonym(s): trich; trichomonal urethritis

Epidemiology

• The most common curable sexually transmitted infection (STI); in 2008, >275 million new cases worldwide, over half of curable STIs (1)
• Estimated 1.1 million new cases annually in United States
  • 10–25% of vaginal infections
  • In males, up to 17% of nongonococcal urethritis
• Predominant age: middle-aged adults
  • Rare until onset of sexual activity
  • Common in postmenopausal women; age is not protective and long-term carriage is common.

Pediatric Considerations
Rare in prepubertal children; diagnosis should raise concern of sexual abuse.

• 1.8% in United States women age 18 to 59 years
• 0.5% of U.S. men age 18 to 59 years
• Racial disparity demonstrated
  • 8.9% of black women versus 0.8% of other women
  • 4.2% of black men versus 0.03% of other men

Etiology and Pathophysiology

• Trichomonas vaginalis: pear-shaped, flagellated, parasitic protozoan
• Grows best at 35–37°C in anaerobic conditions with pH 5.5 to 6.0
• STI, but nonsexual transmission possible because it can survive several hours in moist environment

Genetics
No known genetic considerations

Risk Factors

• Multiple sexual partners
• Unprotected intercourse
• Lower socioeconomic status
• Other STIs
• Untreated partner with previous infection
• Use of douching or feminine powders

General Prevention

• Use of male or female condoms
• Limiting sexual partners
• Male circumcision may be protective.

Commonly Associated Conditions

• Other STIs, including HIV
• Bacterial vaginosis