Trichomonas vaginalis
Anaerobic flagellated protozoan causing trichomoniasis.
Trichomonas vaginalis is an anaerobic, flagellated protozoan parasite and the causative agent of the sexually transmitted disease trichomoniasis. The parasite infects both men and women at similar rates, though women are usually symptomatic while men are usually asymptomatic.
- field
- Parasitology, Infectious disease
- known_for
- Causing trichomoniasis, the most common non-viral sexually transmitted disease
- binomial_name
- Trichomonas vaginalis
- morphology
- Trophozoite only; no cyst form
- treatment
- Metronidazole or tinidazole
Lore & Background
He created the binomial name Trichomonas vaginalis. The parasite exists only as a trophozoite, lacking a cyst form, though a nonmotile, round pseudocystic form with internalized flagella has been observed under unfavorable conditions. It measures approximately 9 × 7 μm, slightly larger than a white blood cell, and has five flagella—four anterior and one posterior—along with a barb-like axostyle. The axostyle may aid attachment and cause tissue damage.
Reader's Guide
Infection is curable with a single dose of oral metronidazole or tinidazole, though resistance is a rising concern. The parasite adheres to vaginal epithelial cells, secretes extracellular vesicles that disrupt immune function, and is associated with disruptions to vaginal microflora. Complications in women include preterm delivery, low birth weight, increased mortality, and predisposition to HIV infection and cervical cancer. Diagnosis is commonly via overnight culture (sensitivity 75–95%), with newer methods like rapid antigen testing and transcription-mediated amplification offering greater sensitivity. Prevention relies on consistent condom use and screening, as no vaccine exists.
Did You Know?
- Trichomonas vaginalis can survive for up to 24 hours in urine, semen, or water samples despite lacking a cyst form.
- The parasite has an amoeboid form on vaginal epithelial cells that increases surface area contact for infection.
- Neutrophils can kill T. vaginalis through trogocytosis.
- The parasite contains hydrogenosomes instead of mitochondria for energy production.
Frequently Asked Questions
Who is Trichomonas vaginalis?
Trichomonas vaginalis is a single-celled, oxygen-averse protozoan parasite that colonizes the human urogenital tract. It exists exclusively as a motile trophozoite with no dormant cyst stage, and it is the organism responsible for the sexually transmitted infection called trichomoniasis.
How does Trichomonas vaginalis's story end?
The parasite is eliminated by nitroimidazole antibiotics, most commonly metronidazole or the closely related tinidazole, which disrupt its anaerobic metabolism and kill the trophozoite. Because no resistant cyst form exists to survive the drug, a complete course of treatment is generally enough to clear the infection.
Why is Trichomonas vaginalis important?
It is the most frequently diagnosed non-viral sexually transmitted pathogen in industrialized nations, infecting men and women at roughly comparable rates. Its enormous global prevalence makes it a persistent public-health burden and a cornerstone topic in parasitology and infectious-disease education.
More in Microbial Pathogens 1-20
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record