Selected fungal and protozoan enteric infections caused by Candida, Blastocystis, Cryptosporidium, and Giardia species

Abstract

With the appreciation of a growing range of enteric pathogens, our understanding of the etiologies of many cases of acute and prolonged diarrhea once undiagnosed are now better understood. Furthermore, there is an increased appreciation for the problem of diarrhea in the nosocomial setting and in immunocompromised patients, where such agents such as Cryptosporidium and Candida organisms appear to play a role. This review discuses recent developments regarding four selected fungal and protozoan enteric infections caused by Candida, Blastocystis, Cryptosporidium, and Giardia species. Reports on Candida enteritis, diagnostic methods, and pathogenic mechanisms for invasive candidiasis are reviewed. Evidence for the pathogenicity of Blastocystis hominis is summarized. Active work on new animal models, immunology, epidemiology, and treatment of cryptosporidiosis is reviewed, with evidence of frequent asymptomatic small bowel carriage in one report. Reports are given of culture and immunologic diagnostic methods, asymptomatic infections, and a role for cellular immunity in pathogenesis of giardiasis. Finally, a useful evaluation of water treatment methods is summarized.