I refer to previous correspondence concerning the potential for human health effects of the
proposed widespread release of rabbit calicivirus (RCV). You will recall my initial advice
provided to you on 12 March 1996 expressed a heavily qualified opinion, that in light of the
available information, RCV was unlikely to pose a significant threat to human health.
Since that time you will be aware that a human health study has been undertaken on a group of
269 people,159 of which had been occupationally exposed to rabbits infected with RCV. The
study sought evidence of clinical effects or measurable specific antibody responses in humans
attributable to exposure to RCV within the preceding 12 months. No serological evidence of
human infection with RCV was obtained. In addition, there was also no detectable temporal
association between exposure to RCV and incidents of clinical illness. Reports from
laboratories and people working with RCV overseas have also indicated a lack of clinical
effects associated with exposure to RCV.
While at this stage, there is no guarantee of human safety with respect to exposure to RCV, I
am satisfied that the above findings do not provide evidence that RCV is associated with
infection or disease in humans. On this basis, and with the limitations of the study in mind, I
have no objections to the controlled release of RCV as a means of rabbit control.
Yours sincerely
A. I. Adams
Chief Medical Advisor
23 August 1996