Enterohemorrhagic Escherichia coli
Escherichia coli O157:H7 is the notorious and prototypic enterohemorrhagic E. coli (EHEC) that causes severe disease in humans. Dutch Belted and New Zealand White rabbits are experimentally susceptible to O157:H7 E.
coli infection and disease and natural infections in wild rabbits have been documented. Dutch Belted rabbits have also been found to be naturally infected with an EHEC strains O145:H(-) and O153:H(-). EHEC strains are attaching and effacing, while also producing Shiga toxins, and are thus termed Shiga-toxin-producing E. coli (STEC).Pathology
Clinical signs among affected rabbits varied from profuse diarrhea to acute hemorrhagic diarrhea. Anorexia, lethargy, and dehydration were other presenting signs. Petechiae and ecchymoses may be present on the serosal surface of the cecum and colon, with edema of colonic and cecal walls. On histopathology, sloughing of enter- ocytes, vasculitis, marked edema in the lamina propria and submucosa, and polymorphonuclear cell infiltration are present. Changes in the cecal mucosa vary from erosion to ulceration, with progression to a fibrinone- crotic typhlitis in severely affected animals.
Dutch Belted rabbits naturally infected with EHEC O153 or experimentally infected with the O157:H7 strain develop renal disease similar to the hemolytic-uremic syndrome seen in human subjects. Fibrinoedematous vasculitis and constriction of vascular lumina were typical changes seen in interlobular blood vessels on microscopic examination. There was swelling of glomerular tufts with leukocytic infiltration, and subendothelial deposition of fibrinous exudate in glomerular capillaries. Fibrin thrombi were present in some other renal vessels. Intravenous injection of Shiga toxin (Stx2) induced similar severe enteritis and renal injury. New Zealand White rabbits experimentally infected with 0157:H7 develop similar intestinal disease as Dutch Belted rabbits, but did not develop hemolytic uremic syndrome.