ESCHERICHIA COLI infection of the gastrointestinal tract may cause diarrhea by two pathogenic mechanisms that have been well described in laboratory animals and man: direct invasion of the intestinal mucosa and production of either heat-labile or heat-stable enterotoxin.^{1 2 3 4 5} Recently, a third mechanism has been described by Cantey and Blake, who studied a rabbit model infected by orogastric inoculation with Esch. coli 015 (RDEC-1).⁶ This infection is characterized by destruction of microvilli and adherence of bacteria to the damaged luminal surface of the intestine in the absence of bacterial invasion or enterotoxin production.⁷ To our knowledge, this histologic finding has not . . .