In 1984 the first outbreak of RHD 1 virus was documented in China. Within 12 months it had killed 140 million domestic rabbits. RHD 2 virus emerged in France in 2010, spreading to the UK in 2014. With outbreaks spreading throughout the UK devastating wild populations, wiping out years of blood lines in studs and killing many pet rabbits.
The quarantine period was decided by the BRC in 1992, as a result of the original outbreak of RHD 1, to limit the spread of RHD 1 and protect the lives of many rabbits, after studying the available research data.
Review of more recent research has confirmed that 4 months is still the most suitable quarantine period and not prolonged.
Rabbits that become infected with RHD and survive, develop an immunity, but continue to be contagious for up to 2 months excreting virus particles into the environment through saliva urine and faeces. These particles can retain infectivity for 1 – 1.5 months in the environment, providing a reservoir which could lead to delayed outbreaks. Ultraviolet light and drying will decrease virus survival whilst cool moist conditions prolong the virus survival time period. Viral particles in rabbit carcases can remain infectious for at least 3 months, but hopefully carcases would not be left on a breeder’s premises after an outbreak, although this is a likely situation in wild rabbit populations. With this information it would be best to double bag carcases and arrange incineration, rather than bury the carcases. Newly infected rabbits show symptoms within 3 – 9 days (the incubation period for RHD 2). So 4 months quarantine in only a narrow margin assuming each of these phases reaches its limits.
RHD virus outbreaks in the UK tend to peak in the Summer and Autumn due to flies and other insects spreading the virus, and an increased population of young non immune rabbits. Rabbits become infected through direct contact with infected animals, water/food bowls, cages, bedding, handlers clothing, contaminated fur, insects and wild animals. Predators such as foxes can spread RHD virus in their faeces after eating infected rabbits.
After an outbreak of RHD, to limit spread to local studs, pets and wild rabbit populations, biosecurity is paramount, using disinfectants such as 10% household bleach, 1% sodium hydroxide and some commercial disinfectants. Alcohol hand scrubs are more effective than chlorhexidine scrubs. Changing clothing and footwear, using foot baths, control of insects and rodents, limit access to essential personnel only (and no visits to any premises with rabbits), careful disposal of bedding and carcases, and halting breeding programs.
Vaccination is paramount but cannot provide total protection to young stock. The vaccinated doe will pass on immunity to babies but there will be a period between 4 and 10 weeks where this immunity starts to wane and the response of the baby rabbit to vaccination is variable leaving some susceptible to infection. Suspension of shows and 4 months quarantine are vital to limit spread to your stud.
Jason Burgess B.V.Sc.,(Hons) M.R.C.V.S.,
Veterinary Advisor to the BRC