Here is a paper produced at a New Zealand Conference in late 1998 showing high RCD antibody
levels in Cats and other animals (antibody levels of over 50%) .
MINISTRY OF RESEARCH, SCIENCE & TECHNOLOGY
RHD Science Seminar RHD - One Year On
3 September 1998
Richard Heyward1, John Parkes2 and Grant Norbury1.
Landcare Research: PO Box 282, Alexandra; P0 Box 69, Lincoln.
Feral cats, ferrets, harrier hawks, and to a lesser extent hedgehogs, use rabbits as a food source either by scavenging or predation By eating rabbits that have died of, or are infected with, RHD they may produce antibodies in response to the virus, as occurs in foxes (e.g., Leighton at at 1995, Journal of Wildlife Diseases 31: 541-44) Hares, a close relative of the rabbit, may be at risk from cross-infection. Our objective was to determine whether any predators, scavengers, or hares produced an antibody response when exposed to rabbits with RHD.
We collected serum samples from predators and scavengers, from an area of mass biociding in the Mackenzie Basin and from spot-baited areas in North Canterbury, during February and May 1998. The samples were tested for RHD antibodies using a competition ELI SA test at' 1:40 diluton. We also tested small numbers of cats, ferrets, and hares from areas without RHD.
Fifty-three percent (n=51) of cats, 10% (n=51) of ferrets, 11% (n=18) of hawks, and 3%(n=30) of hedgehogs were seropositive (Those with greater than 50% inhibition).
There was a bimodal distribution of antibody levels for all animals except cats. The proportion of seropositive animals was higher in February than in May.
Although about equal numbers of male and female ferrets were sampled, only female adults were seropositive. No juveniles were seropositive, which suggests ferrets had to be alive during the epidemic and that RHD was not active at these sites in 1998.
No hares (n=34) from the Mackenzie Basin, where RHD had occurred, were seropositive.
In areas where RHD had apparently not occurred, no predators or scavengers were seropositive. However, one of five hares sampled from inland Canterbury was seropositive (75% inhibition at the 1:40 dilution).
This work was funded by MAF. We thank Canterbury Regional Council and Mr K. Prime and Ngati Hine for providing some of the samples.
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