Description

• Sexually transmitted urogenital infection caused by a pear-shaped, parasitic protozoan
• Causes vaginitis/urethritis in women, nongonococcal urethritis in men
• Association with infertility in epidemiologic studies
• 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

Incidence

• The most common curable sexually transmitted infection (STI); in 2008, >275 million new cases worldwide, over half of curable STIs
• Estimated 1.1 million new cases annually in United States
  • 10–25% of vaginal infections
  • In males, up to 17% of nongonococcal urethritis; French study shows decreasing prevalence in men since 2007.
• 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.
• Neonatal infections occur most often in the lungs, also vaginal (1)

Prevalence

• 2.1% in U.S. women aged 14 to 59 years
• 0.5% of U.S. men aged 14 to 59 years
• Racial disparity demonstrated
  • 9.6% of black women versus 0.8% of other women
  • 3.4% 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
• Divides by binary fission, does not have a cyst form so does not survive externally
• 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
• Hormonal contraception use does NOT increase risk.

General Prevention

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

Commonly Associated Conditions

• Other STIs, including HIV, increases risk of STI (1)
• Bacterial vaginosis (1)