Epizootic Rabbit Enteropathy: experimental transmission and clinical characterization

Abstract

In late 1996 in France, a severe digestive disease appeared in fattening domestic rabbits. Named the Epizootic Rabbit Enteropathy (ERE), this digestive syndrome has become the main cause of mortality in rabbit farming. The diagnosis in field conditions is difficult because co-infection with other common rabbit pathogens is frequent. By using specific pathogenic free (SPF) rabbits and starting from a field sample of intestinal contents of diseased animals, a virulent material (inoculum) was obtained free of almost all known pathogens but reproduced the symptoms and lesions of ERE. Four hundred and seven SPF rabbits were used in five trials to describe the disease. ERE is characterized by a high contagiousness, 30 to 40% mortality in a few days and about 100% morbidity whatever the dose of the inoculum used. Clinical signs and lesions evolved acutely with the first sign (rambling noise) appearing one day after inoculation and the disease peaking 4 to 6 days later. Growth was strongly lowered from the second day to the end of the second week. Rambling noise and distended abdomen were frequent, mucus excretion and cecal impaction were frequent but not constant. ERE at necropsy was characterized by the absence of any inflammatory or congestive lesions on the gut or on other organs but with the typical presence of a stomach and/or duodenum dilated by liquid and gas and by the absence of specific histological lesions. The etiological agent has not been identified yet, but we demonstrate that the intestinal content was infectious as early as the second day. This work constitutes the experimental basis for studies on this emerging disease within the framework of etiological research led in different European laboratories working with the infectious material.