Trichomonas vaginalis

More often known as "trich," trichomoniasis is the most common curable STI in young, sexually active women. In fact, 7.4 million Americans are infected every year and 174 million are infected globally! The infection is caused by a small, single-cell parasite (Trichomonas vaginalis) within the vagina of females or urethra of males. Trich usually causes the onset of certain conditions such as vaginitis, a yeast infection, or bacterial vaginosis (a conditions in which the natural flora--bacteria--overwhelm the body creating unnatural symptoms and discomfort).

How is it transmitted?

This parasite is transmitted through sexual intercourse. Both males and females are susceptible. Other non-sexual forms of transmission are possible but are extremely rare.

How can you protect yourself?

Condoms and spermicides are useful for reducing the rate of infection, but are not 100% effective. Because Trich can be easily treated, routine STI testing is recommended. Trich testing is not part of your normal STI testing, so ask your doctor for an easy trich test if you think you may have been exposed.

What are the symptoms in women?

Almost 50% of infected women are asymptomatic. Symptoms can include discharge (green-yellow frothy odorous secretions) and itching. The symptoms appear 5 to 28 days after infection.

What are the symptoms in men?

Infections in men are usually asymptomatic, which unfortunately is the reason why most men remain untreated and continue to re-infect their partners. Trich causes 5 to 15% of nonspecific urethritis and cystitis in men. Consequently, men can experience slight burning after urinating or ejaculating, irritation inside the penis, and mild discharge. One-third of the infected men experience spontaneous resolution (the infection heals itself), yet the long-term infection may cause prostate inflammation and cancer.

How is it diagnosed?

The most common diagnosis is through an overnight culture, but a visual diagnosis can be obtained through viewing fluids under a microscope for the presence of the Trich parasite. Genital fluid is collected from patients using swabs in both cases. A physical examination along with one of these two laboratory tests is required to diagnose Trich.

What is the treatment?

Trich is treated with a single dose of an oral antibiotic, metronidazole (Flagyl). Other treatments options are currently being researched because drug resistance to the current treatment is growing.

What are the long-term health effects?

New research has found a correlation between infected males and increased risk of prostate cancer. In women, trich has been found to increase the risk of HIV infection, AIDS, and cervical cancer. Pregnancy, while infected with Trich can be very dangerous for the baby (leading to impaired IQ, lower birth rate, etc), yet testing is not routine during or before pregnancy. Trich can also cause short term health effects such as pneumonia, bronchitis and oral lesions.

Additional facts:

  • The Trichomoniasis parasite was first found in birds, but mutated into the human-dwelling parasite Trichomonas vaginalis.
  • It is estimated that a new person is infected every 9 minutes across the globe.
  • In 2004, a new (oral or vaginally inserted) antibiotic, Tinidazole, was approved by the FDA to use along with oral antibiotic Metronidazole. This is successful for treating most Metronidazole resistant strains; however, some strains are resistant to both. Research on treatment of these co-resistant strains persists.

If you or your partner is having symptoms related to Trich, talk to your physician about getting tested. For more information about Trich, you can  email the CDC at or check out their website here.