Case Presentation
An 18 year old girl presents to her pediatrician with her mother for her pre-college check-up. She has no past medical history. After her mother leaves the room for the social history component, the girl admits to having sex with her boyfriend for the first time two weeks ago and complains of a yellow green malodorous vaginal discharge that started a week ago. She endorses mild pelvic pain. A pelvic exam is performed and mild cervical tenderness is noted. The cervix is pink, nulliparous, inflamed and is covered by small red punctate spots. A thin yellow green frothy discharge of fishy odor is also detected. A wet prep is made and reveals squamous cells and numerous motile organisms.
Discussion
Our patient was diagnosed with Trichomonas vaginalis (TV). TV is a flagellated parasitic protozoan for which humans are the only known host. It is 10-20 um long and 2-14 um wide with multiple flagella projecting from the anterior and posterior sides. It has a single trophozoite stage and does not survive well outside of its host. TV is a predatory obligate parasite that eats bacteria, vaginal epithelial cells, and red blood cells. It uses fermentative metabolism to produce the carbohydrates needed for fuel. TV is a sexually transmitted disease; however, because it is not reportable to local health departments, the true epidemiologic incidence rate is unknown. Its prevalence is highly variable by population and location. For example, some studies cite a prevalence of 3.1% of American pre-menopausal women (2.3% of adolescents) [1], while in certain high-risk populations the rate might be as high as 47% [2]. Most affected patients are asymptomatic; about a third of females become symptomatic within six months of infection. Symptoms for females include vulvar and vaginal irritation and itching, pain with urination and a diffuse, malodorous, yellow-green vaginal discharge. The cervix becomes reddened in a punctuated fashion causing the well-known strawberry cervix seen on colposcopy. In males, urethritis can develop. TV is often diagnosed via wet mount microscopy, where the protozoa can be seen moving around (Video 1). However, the sensitivity is relatively low, especially among males. Detection by nucleic acid probe from urine, endocervical, and vaginal swabs are considered more sensitive. TV can also be incidentally discovered on Pap tests (Figures 1 and 2). Treatment typically consists of a single dose of metronidazole [1,2]. It is critical that partners be treated as well, because otherwise reinfection may occur.
References
- Kissinger P. Trichomonas vaginalis: a review of epidemiologic, clinical and treatment issues. BMC Infectious Diseases. 2015; 15(307): 1-8.
- Meites E et al. A review of evidence-based care of symptomatic trichomoniasis and asymptomatic Trichomonas vaginalis infections. Clinical Infectious Diseases. 2015; 61(S8): S837-48.
-Amanda Strickland, MD, is a 2nd year Anatomic and Clinical Pathology Resident at UT Southwestern Medical Center.
–Erin McElvania TeKippe, PhD, D(ABMM), is the Director of Clinical Microbiology at Children’s Medical Center in Dallas Texas and an Assistant Professor of Pathology and Pediatrics at University of Texas Southwestern Medical Center.
Lablogatory 
My question about this case is whether it is felt that the TV was introduced by the boy or that the girl may have harbored the TV without symptoms and after sex and irritations, perhaps douching, the organism proliferated. Thank you for the case.