Prevalence of intestinal pathogens in HIV patients with diarrhea: implications for treatment

Patients infected with the human immunodeficiency virus (HIV) commonly experience diarrhea at some time during their illness. A variety of enteric pathogens are identified in 50-80% of these patients, depending on the intensity of the diagnostic work-up that is done. In addition to the common enteric pathogens, several unusual enteric pathogens are recognized to cause diarrhea especially in HIV patients. These include protozoan parasites such as Cryptosporidia, Isospora belli, Cyclospora cayatenensis and Microsporidium species bacteria such as enteropathogenic Escherichia coli and Mycobacterium avium-intracellulare, fungi including Candida albicans and Histoplasma capsulatum, and viruses such as astroviruses and caliciviruses. Diagnosis of these infections sometimes involves special procedures not readily available every where, and empiric therapy based on knowledge of the likely pathogens has been advocated for developing countries. This article reviews the currently available data on geographic variation of enteric pathogens in HIV patients with diarrhea and outlines a rational strategy for empiric therapy of these patients.