Canada’s National Center for Foreign Animal Diseases (NCFAD) has reported positive results for rabbit hemorrhagic disease (RHD) virus by conventional RT-PCR and the finding of a Calicivirus-like agent by electron microscopy.
On March 30 a domestic neutered male rabbit presented at a local veterinary clinic with lethargy and a yellow matter was observed on its fur. It was diagnosed with liver failure and died during treatment. The body was forwarded to the Manitoba Ministry of Agriculture, Food and Rural Initiatives (MAFRI) laboratory.
Findings included jaundice, hepatic necrosis, some hemorrhages, moderate meningoencephalitis and mild nephritis. A liver sample was sent to the Canadian Food Inspection Agency (CFIA) and NCFADto rule out RHD virus.
The positive sample’s nucleotide sequence had the closest match in Genbank with an RHD virus isolate from China from 2006. On April 20 and 21, histopathology confirmed lesions consistent with RHD and positive staining for RHD virus antigens was shown by immunohistochemistry.
Three test rabbits were inoculated with material from the MAFRI submission on April 26. All inoculated rabbits were strongly positive for RHD virus by conventional RT-PCR. Histopathology on tissue from the inoculated rabbits showed lesions consistent with RHD.
Immunohistochemistry on liver, spleen and kidney from inoculated rabbits showed positive immunoreactivity for RHD virus and electron microscopy of a liver homogenate was positive for Calicivirus-like particles. Sequencing of the PCR amplicons from liver material from the three inoculated rabbits were 100 percent identical with one another as well as the original amplicon from the submitted pet rabbit.
The infected pet was kept in an apartment with two other pet rabbits for more than a year before becoming ill. None of the pet rabbits had contact with commercial or wild rabbits.
After confirmation of the diagnosis on the index case, the two other pet rabbits were inspected and tested by the CFIA with negative results (RT-PCR on blood and cELISA for antibodies) which were released on May 6. Presently, these two pet rabbits remain clinically healthy. The apartment owners cleaned and disinfected the cage and the contact areas of the infected rabbit.
CFIA considers this event in a non-commercial rabbit as resolved.