Answer to the Parasite Case of the Week 626: Trichomonas vaginalis. The images from this case show the classic morphology of this organism. Here are some of these key diagnostic features:
Although T. vaginalis can be seen in vaginal secretions, male urethral secretions, and in urine, the most sensitive detection method is a nucleic acid amplification test (NAAT). This is what we use in my laboratory. Importantly, the NAAT we use does not cross-react with the other trichomonads found in the oral cavity and intestine.
As Sam mentioned, "Treatment with metronidazole would be appropriate. This would be of concern if the patient was pregnant as T. vaginalis can cause premature rupture of membranes, preterm birth, and decreased birth weights." T. vaginalis can also increase the risk of HIV transmission, so treatment is indicated even if the patient is asymptomatic.
Thanks to all who wrote in with comments!