Amebiasis: introduction, current status, and research questions.

This series of five papers on the worldwide problem of amebiasis, its current status, research needs, and opportunities for progress has grown out of a renewal of investigative interest in amebiasis. The recent development of in vitro culture methods and of means to distinguish strain differences and the application of modern tools of cellular biology and biochemistry have raised new questions regarding strain definitions, virulence traits, host defenses, and the mechanism of invasive disease sometimes caused by Entamoeba histolytica. The clinical manifestations of amebic infections range from prolonged asymptomatic carriage to extensive, invasive intestinal and extraintestinal disease. The virulence traits of the parasite, whether stable in each strain or alterable by environmental or genetic factors, and the host factors involved in the development of disease and in protection have been investigated. From this series of reviews on the definition of amebiasis, its manifestations, its global magnitude, the methods for its detection, and the current understanding of its epidemiology, pathogenesis, cellular biology, and host defenses, a list of key questions that can now be addressed in work on amebiasis has been derived. Amebiasis is the third leading parasitic cause of death in the world. The need for work in this field is great, and the time is ripe for the application of new research tools to a better understanding of this remarkable tissue-lysing protozoan parasite and to the control of the disease it causes.