It is funny that we spend so much time talking about the biological impact of the use of transgenic plants for instance, and nobody cares about using an infectious agent, able to kill an animal in two days!

In connection to the above, it is even less admissible the deliberate release of RHDV ignoring:

1)the origin of the virus and the type of changes that converted the hypothetical nonpathogenic ancestor into the virulent derivative.

2)the cell type affected by RHDV and the receptor it uses to infect the susceptible cells.

b)The experiments used to demonstrate the possibility of transmission to humans or other animal species do not rule out that the infection can occur using higher doses, alternative infection routes or a virus inoculum obtained after several passages in susceptible animals. The virus used in the experiments belongs to a particular stage of evolution and this will change after repeated infection rounds.

c)There are naturally resistant or not susceptible rabbits (young animals),which will survive the challenge and that will probably build back rabbit population. These animals might help to select different strains of RHDV with new unpredictable properties.

d)The deliberate release of RHDV in such a large scale will increase the opportunities for the virus to mutate after multiple rounds of infection. On the other hand this will help to spread the disease to other regions (or continents) where the “rabbit problem does not exist.

e)A biological agent as RHDV can not be controlled after it is released. It is very difficult to define for how long it will “survive” in nature and I can not be completely convinced that the actual vaccines will protect against any new strain of RHDV. I have mentioned that some RHD-vaccinated farms in Spain have had outbreaks of RHD. In some cases it seems that this is not due to low immunity but to new strains of RHDV with altered properties.

Concerning your other questions, as a virologist, I would recommend not to consider any kind of virus completely harmless.

As a general rule I would not suggest to eat rabbits dead of RHD or any other disease. It is also advisable to avoid direct contact to dead animals. The use of rubber gloves is always a good idea. In my experience bleach is a good RHDV disinfectant, although other commercial products might be useful as well. I do not find any particular risks for children but it is always advisable that an adult should supervise the disposal of dead animals and the disinfection of hutches.

As a prophylactic measure I will also recommend to vaccinate domestic rabbits to avoid RHD. As far as I know Cylap is an effective vaccine, as many other commercial products. I do not think the problems you have told me can be directly related to the vaccine itself. Certainly I would discard the presence of unkilled pathogens, although considering the complexity of the vaccine I can not rule out some occasional adverse effects.

I would like to thank you for the literature you have sent me. I do not know who you should contact regarding studies of RHD in foxes. Nevertheless, I can give you the address and fax number of Dr J. P. Morisse and G.Le Gall who might be able to inform you about this issue.

Centre National D’etudes Veterinaires et Alimentaires

22440 PLOUFRAGAN (FRANCE)

FAX: 96 01 62 23

After reading the paper you have sent me I realise that they have lost an excellent opportunity to investigate if the seroconversion was due or not to infection. I think they forgot to feed a group of foxes with a RHDV-infected liver extract, after inactivating the virus. This would help to see if the seroconversion occurs, or if it is of the same magnitude than the observed in the animals fed witht the infected liver.