History

Diarrheal diseases have been important to all soci­eties since the beginning of recorded history. Hippo­crates used the term “dysentery” to denote a condi­tion wherein the affected person, experiencing straining and painful defecation, passed many stools containing blood and mucus.

The modern era of diarrheal diseases began, as was the case with other infectious disorders, with the identification of the causative agents involved. During the mid-1800s, Giardia Iamblia and Enta­moeba histolytica were first identified. Then during the latter part of the nineteenth century, Shigella and Salmonella organisms were characterized, and the two forms of dysentery - bacillary and amebic - were distinguished.

During the 1960s, a series of landmark studies helped to elucidate the mechanisms Ofdisease produc­tion when cholera toxin was purified. As an extension of research with V. cholerae during the 1970s, en­terotoxigenic E. coli were identified as important causes of diarrhea. Soon thereafter, other entero­toxin- or cytotoxin-producing bacteria were discov­ered: Salmonella, Aeromonas, Yersinia, Clostridium perfrigens, C. difficile, enterohemorrhagic E. coli, noncholera vibrios, and Staphylococcus aureus.

Also during the early 1970s, viruses were clearly implicated as causes of diarrhea in humans. Initially, Norwalk virus was shown to produce gastroenteritis in volunteers fed bacteria-free stool filtrates derived from an elementary school outbreak in Norwalk, Ohio, and the 27-millimeter viral particle was visual­ized by electron microscopy. Soon thereafter, larger viral particles were observed in the duodenal mucosa of infants with diarrhea, and within a few years rotaviruses were established as a major cause of infan­tile gastroenteritis. Additional pathogens are being identified in cases of diarrheal disease as the research laboratory discovers novel mechanisms of patho­genesis or as new microbiological techniques for isola­tion and identification are developed. The future will bring studies of organism-specific epidemiology, ther­apy, and disease prevention.