Rabbit haemorrhagic disease and the biological control of wild rabbits, Oryctolagus cuniculus, in Australia and New Zealand

Abstract

This review considers the history of the discovery of the rabbit haemorrhagic disease virus (RHDV) and its spread throughout the world in domestic and wild rabbits, which led eventually to its deliberate release into Australia and New Zealand for the control of a major pest, the introduced wild rabbit. The physical and genetic structure of RHDV is now well understood, and its pathogenic effects are also well known. The epidemiology of rabbit haemorrhagic disease (RHD) has been clearly documented in the field in European countries, Australia and New Zealand. Since its initial spread through largely naïve populations of wild rabbits it has established a pattern of mainly annual epizootics in most areas. The timing of epizootics is dependent on climatic variables that determine when rabbits reproduce and the appearance of new, susceptible rabbits in the population. The activity of RHDV is also influenced by climatic extremes that presumably affect its persistence and the behaviour of insect vectors, and evidence is growing that pre-existing RHDV-like viruses in some parts of Australia may interact with RHDV, reducing its effectiveness. The timing of epizootics is further modified by the resistance to RHD shown by young rabbits below 5 weeks of age and the presence of protective maternal antibodies that also protect against fatal RHD. RHD has reduced rabbit abundance, particularly in dry regions, but rabbits in cooler, high-rainfall areas have been able to maintain their populations. In Australia and New Zealand, RHD has raised the prospects for managing rabbits in low rainfall areas and brought substantial economic and environmental benefits.

Origin and Phylodynamics of Rabbit Hemorrhagic Disease Virus

“…RHD occurred in Italy in 1986 in farmed domestic rabbits and subsequently in farmed rabbits in other parts of Europe, Russia, India, the Americas, and the Middle East (reviewed in reference 6). In Europe, RHDV is believed to have spread into the wild rabbit population from domestic rabbits and is now established in wild rabbit populations throughout continental Europe, the United Kingdom, and Ireland, with substantial ecological consequences, particularly in the Iberian peninsula (5,6). After its accidental release in 1995, the Czech v351 strain of RHDV was deliberately spread in Australia and subsequently New Zealand as a biological control for the wild European rabbit (5,6).…”

Timing and severity of immunizing diseases in rabbits is controlled by seasonal matching of host and pathogen dynamics

“…This is because we know that rabbit recruitment varies spatio-temporally in response to climatic variation [24], most probably conditioning host -pathogen dynamics. Although we have provided robust simulation evidence that seasonal interactions can explain RHD epidemics in Australia, future studies should target factors such as the occurrence of possible arthropod vector species, the timing of epidemics and their subsequent relationship to recruitment to further improve our predictions [26]. We therefore emphasize that parameter estimates from our ABC approach should be interpreted cautiously [61].…”

“…Reproduction in this species is adapted to optimize resource use in variable environments, and such plasticity is likely to have enhanced the invasiveness of rabbits, which are now found in many temperate and Mediterranean ecosystems around the world [24]. Rabbit haemorrhagic disease virus (RHDV, an RNA calicivirus) and myxoma virus (MYXV, a DNA poxvirus) have caused significant reductions in rabbit abundances in their native range [25], and they have been used successfully as biocontrol agents in the rabbits' exotic range [26]. Epizootics of RHD (the disease caused by RHDV) are highly seasonal in some rabbit populations, and in cooler regions of Australia, RHDV is less effective as a biocontrol agent than in drier regions [26].…”

“…Rabbit haemorrhagic disease virus (RHDV, an RNA calicivirus) and myxoma virus (MYXV, a DNA poxvirus) have caused significant reductions in rabbit abundances in their native range [25], and they have been used successfully as biocontrol agents in the rabbits' exotic range [26]. Epizootics of RHD (the disease caused by RHDV) are highly seasonal in some rabbit populations, and in cooler regions of Australia, RHDV is less effective as a biocontrol agent than in drier regions [26].…”

The future biological control of pest populations of European rabbits, Oryctolagus cuniculus

“…RHDV resulted in initial reductions of rabbit numbers that ranged from major in arid areas (~85%, approaching 100% in some areas), to small or non-existent in cool, moist areas (Cooke 1999a;Fenner and Fantini 1999;Cooke and Fenner 2002;Edwards et al 2002;Henzell et al 2002). Following its initial success, subsequent RHD outbreaks usually occurred in the presence of the acquired immunity of recovered rabbits, often at different times of the year from the first outbreak, and in rabbit populations that had been reduced in numbers by earlier RHDV outbreaks.…”