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History of rabbit haemorrhagic disease (RHD)

Timeline

1984: A highly lethal disease broke out in rabbits in China (Liu et al. 1984). In less than a year, there was a loss of over 140 million rabbits (Abrantes et al. 2012). The disease was characterised by haemorrhages around the body and a calicivirus was identified as the cause. The disease was named ‘viral haemorrhagic disease’ (VHD) or ‘rabbit haemorrhagic disease’ (RHD) and the latter name has become the standard term in recent years. RHD was transmitted from China to rabbits in Korea by the importation of infected rabbit fur. Subsequently, the disease spread to other parts of the world, almost certainly by trade in rabbit meat and fur, or by consignments of infected rabbits (Cooke, 2016).  

1986: RHD was diagnosed in Italy (Morisse et al. 1991) and by 1988, the disease was reported in other parts of Europe where it had escaped into the wild rabbit population.

1988: Development of inactivated vaccines against RHD (Huang, 1991).

1990: RHD reached Scandinavia. Wild rabbits in the densely populated island of Gotland became nearly extinct within 1 week with hundreds of rabbits dead in the fields and many more dying in their burrows.

1991: RHD was first reported in UK in a group of exhibition rabbits (Fuller et al. 1993) before spreading through the wild and domestic rabbit population.  

1995: RHD was released onto Wardang Island, off Southern Australia, during an investigation into using the virus as biological control of the wild rabbit population. The virus escaped to the mainland where it spread rapidly and became endemic, killing millions of wild rabbits. Within weeks, there was a 95% reduction in the wild rabbit population in a National Park close to the source of the outbreak (Mutze et al. 2013).  

1997: RHD was illegally introduced into New Zealand. 

2000:  The first confirmed case of RHD in the United States occurred in a small breeding colony of exhibition rabbits in Iowa. Twenty-five of the 27 rabbits died with no indication of the source of the infection. Subsequently, sporadic outbreaks of RHD occurred in US, but the disease was contained, probably because the European Rabbit (Oryctolagus cuniculus) does not live in the wild population (Campagnolo et al. 2003). The most common rabbits in the Eastern Cottontail (Sylvilagus floridanus), which was not susceptible to the original RHD virus.

2000-2010: Although RHD was endemic, vaccination programmes were effective in controlling the disease in domestic rabbits. Wild rabbit populations recovered.

Arrival of RHDV2

In 2010, an outbreak of RHD occurred on a rabbit farm in France in which 25% of vaccinated breeding does died. Further outbreaks in vaccinated rabbits took place in north-western France and during the same period, several outbreaks were reported in the wild rabbit population. Tissue samples collected during these outbreaks revealed the presence of a virus that was genetically related to, but different from known strains of RHDV (Le Gall- Reculé et al. 2013). This new virus was named RHDV2.

After its emergence in 2010, RHDV2 disseminated throughout Europe and in 2014, it was reported in the UK where it spread rapidly (Westcott and Choudhury, 2015). By 2016, outbreaks were killing rabbits in rescue centres, breeding colonies and show rabbits as well as individual pets. In 2015, RHDV2 was detected in Australia although it is not clear how the infection was introduced. There was a rapid decline in the wild rabbit population ( Mutze et al. 2018) and, as in many parts of the world, RHDV2 was replacing RHDV1 as the cause of  RHD (McGowan and Choudhury, 2016; Marschang et al. 2018). In April 2018, RHDV2 was reported in a large colony of feral rabbits on a university campus on Vancouver Island, Canada before spreading to other areas of British Columbia. In May 2018, RHDV2 was confirmed in New Zealand. Again, it is not clear how the virus arrived. By July 2019, outbreaks were also occurring in the United States (OIE, World Organisation for Animal Health).