Multiple choice The common cause of the vaginal discharge is Entamoeba histolytica Treponema palladium Polio virus Trichomonas vaginalis Reveal answer Fill a bubble to check yourself D Correct answer Explanation Trichomonas vaginalis is a common protozoan parasite that causes trichomoniasis, a frequent cause of vaginal discharge. Treponema pallidum causes syphilis, and Entamoeba histolytica causes amoebiasis.