Epidemiology of viral haemorrhagic disease and myxomatosis in a free-living population of wild rabbits

Study of mxymatosis and VHD in Spanish rabbits

source: C Calvete et al
Veterinary Record, vol 150, no 25 June 22 2002
starts p 776, 7 pages long

Wild rabbits are important in Spanish ecosystems, and are also hunted for sport. The population dropped after mxymatosis arrived in the 1950s, then rose until the 1980s, when viral haemorrhagc disease (VHD) led to many local populations being wiped out, and numbers overall to drop. There have been efforts to restock, but their success or otherwise is not clear, and research on these diseases has tended to focus on domestic rabbits.

This study of the epidemiology of VHD and mxymatosis in wild rabbits was carried out from January 1993 until June 1996. The location was 250 hectares in the Ebro valley, an area with a semi-arid climate, small fields, and scrub on hillocks where burrows are common. Rabbits were trapped and blood samples taken, and dead rabbits were also examined. Rabbits were also radiotagged.

Rabbits were most likely to die from predation or disease, though some died from flooding. The incidence of disease may be masked by diseased animals being caught more easily by foxes and raptors.

All adult rabbits had antibodies to mxymatosis, and only young rabbits were found with clinical signs of the disease, and this only in spring and winter. Most young rabbits were infected before reaching a year old, and probably caught the disease through fleas.

The population density increased during the study, as did the prevalence of antibodies to VHD. This could be because a less lethal form of the disease had appeared, or it may be that there were fewer predators, with foxes having been affected by sarcoptic mange. Adult rabbits did die from VHD, especially during the winter. This may be because they tended to use their burrows more during the winter, and were more likely to be infected in their burrows. 
RB,HD