Infectious agents associated with epizootic rabbit enteropathy: Isolation and attempts to reproduce the syndrome

Abstract

Epizootic rabbit enteropathy (ERE), a highly lethal (30-80% mortality) disease of broiler rabbits aged 6-14 weeks, first appeared in 1997 in French intensive enclosed rabbitries and is of unknown aetiology. Bacteriological, virological and parasitical examination of the intestinal contents of rabbits that had died either in spontaneous field cases or after experimental reproduction of ERE, were undertaken in an attempt to identify infectious agents that may play a role in the disease. Two bacterial strains, Clostridium perfringens and non-enteropathogenic Escherichia coli were repeatedly isolated at high faecal counts from naturally infected animals. In field cases, a correlation between typical gross lesions of epizootic enteropathy and the presence of the alpha toxin of Cl. perfringens was observed (P<0.0001; Chi-squared test). Although attempts to reproduce the disease by inoculation with different pools of cultivable bacterial strains failed, the disease was successfully reproduced by inoculation with one French and two Belgian samples of caecal contents.

Epizootic Rabbit Enteropathy: experimental transmission and clinical characterization

“…The search for a possible pathogenic agent has only revealed the presence of rotavirus and Clostridium perfringens in all our inocula, but their role remains questionable [5,9,27,28]. Nevertheless, further etiological investigations are necessary, particularly in bacteriology.…”

Characterisation of Clostridium perfringens presence and concentration of its α-toxin in the caecal contents of fattening rabbits suffering from digestive diseases

“…In fact, this toxin hydrolyses lecithin, phospholipids and sphingomyelin and causes membrane disruption (Songer, 1996). In this scope, Marlier et al (2006) established a correlation (P<0.001) between the appearance of ERE typical gross lesions and the presence of the C. perfringens α-toxin. However, it should be acknowledged that in this work some of rabbits for which the α-toxin was not detected presented similar lesions to those with high concentrations of α-toxin.…”

“…Eleven out of these 15 rabbits had caecal concentrations of C. perfringens below the threshold of 6.0 log cfu/g (3.30 log cfu/g, on average). Likewise, Marlier et al (2006) failed to detect the presence of the α-toxin in the intestinal contents of 31.2 and 83.3% of the rabbits that had died of ERE or other digestive disorders, respectively. These negative results are certainly due to the fact that the α-toxin concentration was under the detection limit of the assay.…”

“…Elevated counts (4 to 7 log cfu/g) are often found in the intestinal contents of lambs suffering from enterotoxaemia (Songer, 1996). Marlier et al (2006) isolated C. perfringens in more than 80% of rabbits affected by ERE while Licois et al (2005) and Huybens et al (2009) identified it in the reference inoculum used to reproduce the disease. Additionally, in 83% of the rabbits affected by ERE in which Marlier et al (2006) managed to isolate C. perfringens, faecal counts were above 4 log cfu/g.…”

“…Marlier et al (2006) isolated C. perfringens in more than 80% of rabbits affected by ERE while Licois et al (2005) and Huybens et al (2009) identified it in the reference inoculum used to reproduce the disease. Additionally, in 83% of the rabbits affected by ERE in which Marlier et al (2006) managed to isolate C. perfringens, faecal counts were above 4 log cfu/g. Furthermore, bacitracin, which acts on Gram-positive bacteria like C. perfringens, has been shown effective to control ERE mortality (Duperray et al, 2003; Maertens et al, 2005;Richez et al, 2007).…”