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

Abstract

From January 1993 to June 1996, the epidemiology of myxomatosis and viral haemorrhagic disease (VHD) was studied in a free-living population of wild rabbits (Oryctolagus cuniculus) in Spain by means of serological surveys and radiotracking. Myxomatosis was endemic and associated with the breeding period. Its serological pattern was characterised by a 100 per cent prevalence of antibodies in adult rabbits and a rapid increase in antibodies in young rabbits in their first year. No mortality from myxomatosis was detected in adults, and mortality in young rabbits could not be estimated because of interference by predators and scavengers and the deaths of many radiotagged rabbits inside their burrows. VHD was also an endemic disease associated with the breeding period. Adults had a higher prevalence of antibodies against VHD than young rabbits, reaching values of 80 to 90 per cent. During the study, there was an increase in rabbit numbers as a result of a decrease in mortality from predation which was associated with an increase in mortality due to VHD and in the prevalence of antibodies to VHD. Mortality from VHD was lower in rabbits with VHD antibodies than in seronegative rabbits, but some mortality from the disease was also detected in seropositive rabbits. The annual mean mortality rate due to VHD in adult rabbits was estimated to be 21.8 per cent.

Long-term decline of the European wild rabbit (Oryctolagus cuniculus) in south-western Spain

“…Given that hunting is forbidden within the Doñana National Park, the main factors influencing rabbit populations include (1) bad weather (Palomares 2003), (2) net loss of favourable habitat (Moreno and Villafuerte 1995), (3) mortality caused by myxomatosis and RHD (Calvete et al 2002), and (4) changes in the impact of predation on rabbit populations.…”

“…RHD became enzootic and 5 years later estimated mortalities were close to 30% . Some information on rabbit abundance was available for several areas of Spain a few years after the RHD outbreak (Blanco and Villafuerte 1993;Calvete et al 2002;Palomares 2003), or could be inferred by analysing data up to 2002 (the last year of available information) on the number of rabbits estimated to be hunted in each Spanish province based on the Ministry of Agriculture reports (Piorno 2006;Virgós et al 2007). …”

Establishing a serological surveillance protocol for rabbit hemorrhagic disease by combining mathematical models and field data: implication for rabbit conservation

“…The antibody concentration is expressed in terms of a relative index on immunity (RI) ranging from 1 to 10. Sera with an RI> 2 was considered positive because the antibody concentration is high enough to rabbit face the disease (for details see Calvete et al 2002).…”

“…After several field studies, it is assumed that the effect of RHD is lower in areas of high density because the rabbit population has been 6 reduced proportionately less (Blanco and Villafuerte 1993;Delibes-Mateos 2006). Furthermore, mathematical models predict an average annual high prevalence of animals with antibodies in high-density populations (Calvete et al 2002;Calvete 2006). Therefore, to correctly interpret the results of sampling both population abundance and serology are important explanatory variables.…”

Estudio preliminar sobre la abundancia y distribución del conejo (Oryctolagus cuniculus Linnaeus, 1758), en el Parque Natural de la Sierra de Mariola (Alicante-Valencia)

“…Las transformaciones del paisaje han ejercido una fuerte infl uencia en su entorno, provocando alteraciones socioeconómicas, culturales y en la biodiversidad de la zona afectada (Martínez-Pérez, 2000). En general, el abandono de los cultivos, la intensifi cación de la agricultura (Moreno & Villafuerte, 1995), las enfermedades (Calvete et al, 2002;Calvete, 2006) y la sobreexplotación de los recursos cinegéticos han provocado un considerable declive en las poblaciones del conejo de monte. ÍNDICE Muchos estudios muestran que la abundancia y distribución de esta especie está relacionada con la estructura del hábitat y las manchas que componen el mosaico del paisaje mediterráneo (Soriguer & Rogers, 1981).…”