Enterotoxigenic Bacteroides fragilis was isolated from stool specimens of 8 of 44 diarrheic individuals (ages, 4 months to 69 years). The individuals had watery diarrhea and intestinal cramping; and infants had hyperthermia, vomiting, and blood in the stools. No recognized enteric pathogens were detected in seven of the eight diarrheic individuals positive for enterotoxigenic B. fragilis. The bacterium produced an enterotoxin detectable in concentrated broth that supported bacterial growth. Fifteen adult rabbits with ligated ceca developed fatal enteric disease following intraileal injection with 5 x 109 CFU of enterotoxigenic B. fragilis. Conversely, eight control rabbits injected with nonenterotoxigenic B. fragilis remained clinically normal. As few as 5 x 103 CFU of enterotoxigenic B. fragilis caused fatal enteric disease in the rabbit model. Disease in rabbits was characterized by mucoid, often hemorrhagic, diarrhea. The bacterium colonized the caudal small intestine and the colon of the rabbits and caused moderate to severe necrotizing colitis. Enterotoxigenic B. fragilis is widespread in the intestinal tract of diarrheic humans and is enteropathogenic in adult rabbits with ligated ceca. Its possible role in the enteric disease complex merits further study.

Abstract. Laboratory records and histologic material from 13 cases of naturally occurring, early-to lateterm bovine abortion due to Tritrichomonas foetus were examined. Placentitis was present in all placentas. Pyogranulomatous bronchopneumonia was in six of the 1 1 lungs which were examined. Trichomonad organisms were demonstrated within the placental stroma in all cases and free or phagocytized in pulmonary airways in seven cases.

An epizootic of infectious keratoconjunctivitis occurred in bighorn sheep (Ovis canadensis) in Yellowstone National Park during the winter of 1981-82. The causative organism was identified as Chlamydia sp. Mortality related to the epizootic was approximately 60% of an estimated 500 bighorn sheep in the northern range population. The infection probably affected all sex and age classes, but field surveys of live animals and mortality suggested that mature rams died disproportionately. Limited field observations the following winter on individuals having both normal and cloudy-appearing eyes suggested that half of the bighorns then present on the core units of winter range had contracted the disease and survived. By 1988, there were about 300 bighorn sheep in the population.

This preliminary report describes an adenoviral infection recently recognized in Arabian foals. Clinically, the condition is suggestive of pneumonia and is frequently progressive and fatal. This article refers to 10 cases that had similar histories and postmortem lesions. The presence of large amphophilic intranuclear inclusions in respiratory epithelia of all cases suggested a viral etiology and prompted the current investigation.

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