It is my great pleasure to participate in this Symposium honoring Paul Beaver, who has taught us so much about parasitic diseases. Entamoeba histolytica is one of many human parasites now subject to intense investigation with the newest methodologies in in vitro cell biology, protein biochemistry, and molecular biology. Recent work has advanced our knowledge of parasite virulence, pathogenic mechanisms, and host immune responses. However, basic questions raised in clinical and animal studies regarding the biology of E. histolytica have yet to be answered.

D'Alessandro has pointedly summarized the contributions of Dr. Beaver to amebiasis research including epidemiology and treatment of human amebiasis, experimental human and animal infection, and in vitro viability of E. histolytica cysts. In October of this year, Dr. Beaver identified important questions which we must answer before we can truly understand E. histolytica infection and disease causation.

In this study of naturally acquired amebiasis in New and Old World monkeys by Beaver and coworkers,1 fatal amebiasis was found to be more common in New World monkeys, suggesting species specificity for susceptibility to invasive disease.