28 May New variant of rabbit hemorrhagic disease virus
In the year of 2010 a new variant of rabbit hemorrhagic disease virus (RHDV2 or RHDVb) was identified in France, and rapidly spreaded throughout the rest of Europe. The vaccine against rabbit hemorrhagic disease that we had been using until then didn’t protect the rabbits from getting infected with the new virus, and in the Barcelona area we witnessed how a few pets passed away. Nowadays the virus has been isolated in islands, like the Canary islands, and places as far away as Australia or Canada. Transmission in this virus occurs just like in RHDV1, through direct contact with excretions and secretions from diseased animals, but also through vectors and fomites.
The virus’ pathogenic potential has not been established. According to epidemiologic studies it is smaller than RHDV1’s (30-70%), while in experimentally induced infections it turns out to be quite simmilar to RHDV1’s (80-100%). Scientists agree that the new variant is replacing the old one in all the rabbit populations in which is has been detected.
The virus' pathogenic potential (...) turns out to be quite simmilar to RHDV1's (80-100%)
The vaccine was registered again in April. In this new registry it is stated that the vaccine is effective 9 months after its administration (which is tested by exposure to the virus). However, vaccinated rabbits were tested 12 months after vaccination and the antibody levels they showed were identical to the antibody levels at 9 months after vaccination. Thus, the vaccine’s duration is probably longer than stated, even though it has not been tested by exposure to the virus.
It’s not necessary to inject the vaccine on the lateral aspect of the thorax, as the prospectus states. European rules say that the prospectus must reflect the exact way the vaccine tests have been carried out at the laboratory, and in this case it was done this way. But it can be safely injected in the interscapular area.
This vaccine can be safely given to pregnant females, and it has also been succesfully tested in dwarf rabbits. None of these dwarf rabbits had any fever after the vaccine was given, although I have seen some cases of fever associated to RHDV2 vaccination which didn’t have any important consequences.
Even though the vial is a multi-dosage one it doesn’t need to be discarded once it has been used for the first time, since it’s an inactivated and already mixed vaccine. The problem with its conservation is not the virus’ viability but the risk of contaminating the vial’s contents after subsequent injections. In any case Hipra is just about to launch a new monodose presentation at the end of June (with a sticker! Just like real veterinarians!).