Abstract :
[en] Rabbit haemorrhagic disease (RHD) is a highly infectious and fatal disease of the European
rabbit (Oryctolagus cuniculus), responsible for important economic losses in the rabbit
industry. The aetiological agent of the disease is a RNA virus (RHDV, Lagovirus,
Caliciviridae) first detected in China in 1984. Currently RHDV is endemic in most parts of
Europe, Asia and North Africa. Phylogenetic analyses of RHDV strains have identified 3
distinct groups : the classic RHDV, the variant RHDVa and RHDV2. This latter has been
detected in France for the first time in 2010 in domestic and wild rabbits (Le Gall-Reculé G et
al., 2013) and since then has spread throughout Europe, replacing the circulating
RHDV/RHDVa strains in most european countries. RHDV2 has already been detected in
Belgium in rabbitries (Marlier D et al., 2014). Here, we report for the first time the presence of
RHDV2 in wild rabbits in Southern Belgium.
In november 2015, the Surveillance Network of Wildlife Diseases received seven dead wild
rabbits for necropsy. The discovery of 7 fresh carcasses found at the same time in a same
area (Hainaut province) emphasised the infectious or intoxication hypothesis as cause of
death. Postmortem examinations were performed at the Faculty of Veterinary Medicine
(FVM) of the University of Liege according to a systematic protocol based on gross lesions,
histopathological and targeted microbiological analysis. For necropsy, each rabbit (1) was
weighted and age was determined by the presence/absence of the distal ulna protuberance,
(2) stomach was investigated to exclude poison, (3) spleen was systematically driven into
Yersinia CIN culture media for detection of Yersinia pseudotuberculosis, (4) lungs and livers
were systematically (a) packaged into 10% formaldehyde solution for histopathology analysis
(Service of Pathology, FVM) and (b) frozen at -20°C for RHDV analysis (Scanelis
Laboratory,Toulouse, France) and finally (6) feces were gathered for parasitology (Service of
Parasitology, FVM).
At necropsy, animals (5 adults: 3 males/2 females and 2 juveniles: 1 male/1 female) were in
good condition. No hematomas or broken bones were detected, only one displayed clues of
diarrhoea. Examinations of the carcasses showed congestion of lungs/kidneys and livers
were macroscopically normal. No foreign body or suspicious particles was seen in the
stomachs, only one rabbit was hardly infested by tapeworms in the gut. Histopathological
examination revealed haemorragic lung lesions in one animal while 5 of them presented
severe necrotic hepatitis, sometimes associated with peri-angiocholitis. Only one animal
presented an abnormal high rate of coccidia in feces. Samples of livers were sent to Scanelis
Laboratory for RHDV RT-qPCR diagnostic. The results were positive for the new variant
RHDV2 in 5 out of the 7 rabbit livers. All the samples were negative for the classic RHDV.
To determine if RHDV2 was already present before 2015 in wild rabbits in the region, we
tested a series of livers that had been collected in 2013 and 2014 for a retrospective study.
Among the 25 rabbit livers checked, 12 presented necrotic hepatitis and were sent for
analysis. Ten were confirmed positive by RT-qPCR for RHDV2.
