Sexually transmitted protozoal infections. Trichomonas vaginalis, Entamoeba histolytica, and Giardia lamblia.

Collectively, protozoa account for the largest number of STDs worldwide. Although these organisms can be eradicated effectively in the individual patient, their high asymptomatic carriage rate appears to have a significant influence on their continued transmission. The best hope for eradication of these organisms lies in a high index of suspicion in high-risk populations and the careful evaluation and treatment of sexual partners of infected persons.