1)Do you believe that RCD differs from the other caliciviruses such that it is entirely specific to one host - the European Rabbit?

2)What would you believe to be the current state of knowledge about RCD? Is it such that you would be confident to recommend its use as a biological agent against rabbits in New Zealand?

3)Is there anything else you believe New Zealanders should know about viruses such as RCD?

4)Can you tell me what procedures are in place in the U.K. to assess and decide about the release of diseases for biological control?

5)Can you suggest others whose opinions I should seek on the questions above?


The letter of reply follows.


Dr. R. Gaskell
Mr M. Glenn
Mr A. Radford
Faculty of Veterinary Science,
University of Liverpool
Wirral, UK

6th November 1996


Dear Ms Van Roy,

Regarding your letter on rabbit calicivirus disease (RCD) and its potential use as a biological control agent in NZ. Firstly, this is a collective reply from our group and represents the thoughts of Dr R.Gaskell, Mr M Glenn and Mr A Radford. Although our work is primarily with the feline calicivirus, we hope you find the following comments in answer to your specific questions useful.

1) We are not aware of any evidence for replication of RCD virus in other species. However, the nature of RNA viruses is to evolve extremely rapidly. We do not know where the majority of caliciviruses came from (spread from marine organisms has been postulated by some) and equally, we do not know where they are going. One thing would appear to be clear - RNA viruses like RCD virus are ideally suited to finding and exploiting new and divergent host species.

2) Although it is possible or even probable that RCD would eventually make it to New Zealand itself, we feel that available knowledge on RCD and RCD virus is still very limited and therefore would not be confident in recommending the use of this virus as a biological control agent.

3)Apart from the above, we have grave concerns about the welfare of rabbits affected by RCD. We have heard supporters of its use claiming that rabbits with RCD are not suffering because for the 24 hours prior to death, they do not move around very much. We have contacted a laboratory animal veterinarian and he would almost reverse the argument to say that because the animals are not struggling, they may be in a lot of pain. Animals do not necessarily express pain in the same way we do. If RCD virus is to be used in NZ, we feel the public should be aware of possible welfare implications.

4) Sorry, that is not our area of expertise: Dr D. Chasey and colleagues at the central veterinary lab., Weybridge may be able to help.

5) See 4: and we presume Alvin Smith has given you other relevant names in the UK.