RABBIT CALICIVIRUS/RABBIT HAEMORRHAGIC DISEASE - A FACT SHEET
How to limit outbreaks of Rabbit calicivirus in pet, farmed and laboratory rabbits
What can you do?
I. Prevent introduction of the disease in your establishment
1. keep rabbits caged in order to prevent any contact with wild rabbits,
2. avoid direct contacts of any kind with other rabbitries and traditional farms (shows and the like, new introductions of rabbits, sharing equipment, allow no visits to any other person(s) unless precautionary disinfection measures are properly taken),
3. consult a nearest veterinary practitioner on feeding practices (purchase and safe feeding green food and forage),
4. provide for thorough disinfection of hands, clothes, shoes, tools, etc, every time before and after any contact with rabbits,
5. take effective measures to prevent/limit contact of rabbits with other livestock including dogs and cats,
6. take effective measures to control presence of rodents, scavengers and insects to prevent/limit their contact with rabbits,
7. protect your rabbits by an officially approved vaccine.
What needs to be done should you suspect the presence of rabbit calicivirus disease?
Basic characteristics of rabbit calicivirus disease are given in Appendix 1. Should you suspect any signs that correspond to those outlined, the following need be done immediately:
1. Contact your agricultural authority
2. Prevent any kind of movement to or out of your premises until you hear back from Agriculture staff,
3. Do not dispose of rabbits prior to consultation with Agriculture staff.
What actions will be taken by the Ministry of Agriculture?
There are developed contingency plans to deal with outbreaks of rabbit calicivirus should they happen either: in wild rabbits, and/or in pet, farmed or laboratory rabbits (these contingencies aim to prevent introduction and limit the disease spread in these populations of rabbits).
To limit spread of the disease from wild rabbits to pet, farmed and laboratory rabbits the following methods may be applied by Agriculture staff should such an event occur in wild rabbits
a) destruction of affected and in-contact rabbits,
b) strict movement control measures and cleaning, disinfection and disinsection as appropriate (apply to staff involved in managing the disease, farmers, residents, other species of animals within controlled areas, contract machinery and vehicles, and other agricultural products such as wool, hay silage and crops).
In addition to the specific contingency plans to deal with eventual outbreaks of rabbit calicivirus in wild rabbits, Agriculture will further ensure that the following criteria be satisfied when dealing with the disease:
a. Movement of staff involved in managing the disease
No entering or leaving properties without proper cleaning and disinfection of boots, cloths, hands and tools,
b. Movement of other species of animals within controlled area
No restrictions if send for slaughter, if different from the above, not permitted to move from restricted premises
c. Movement of dogs and cats in Controlled area
Not permitted, they would need to be restrained on the property where they belong, rural working dogs would need to be chained or kennelled,
d. Contractors machinery trucks, movers, etc which could have contained grass need to be thoroughly cleaned and disinfected,
e. Wool and other agricultural products (hay, silage, crops)
Not permitted to move out the controlled area while emergency in place.
As mentioned, Agriculture deprtment will maintain the above plans in force. However, some of the criteria above can be efficiently applied by owners at their discretion.
This information is provided:
a) to rabbit breeders, owners and the public dealing with rabbits to support the control measures, and
b) for use of an officially approved vaccine.
A killed RCD vaccine has been registered for use in some parts of the world and may become available if the government approves its use. The vaccine would be available to protect pet, farm and laboratory rabbits prior to any decision to deliberately release rabbit calicivirus virus.
Laboratory rabbits
Laboratories should follow the principles of Good Laboratory Practice in handling laboratory rabbits.
Restocking of rabbits
1. Rabbit sheds, cages, walls floors and tools must be thoroughly disinfected (Virkon, 10% bleaching powder or 3% formalin followed by 2% sodium hydroxide),
2. Sentinel rabbits need to be introduced a month after completion of disinfection and tested in due course with a negative result,
3. Rabbits for restocking should be sourced from negative farms.
Appendix 1. RABBIT CALICIVIRUS DISEASE
Introduction
Rabbit calicivirus disease is an acute fatal disease of rabbits with a high morbidity and mortality. The disease occurs throughout the year. The transmission is by direct and indirect contact and through all routes. There is no evidence of congenital infection.
Aetiology
The disease is caused by a virus and it was first reported in farmed rabbits in China in 1984, but has since been found in many countries in Asia, Europe and Africa and in Mexico.
Epidemiology
Occurrence
Only the European rabbit, Oryctolagus cuniculus is susceptible. Susceptibility is influenced by age; rabbits less than one month old of age are fully resistant to natural infection, those between one and two months of age may be affected but at a low percentage, while rabbits older than two months are highly susceptible.
Transmission
The virus is present in blood, organs, secretions, excretions and on skin and mucous membranes, principally during the late stage of infection and after death. It has been shown that the virus is very stable at low temperatures and survives for 560 days at -20oC, up to 225 days at 4oC, for 105 days at 20oC when dried on cloth and 2 days at 60oC.
Therefore, possible sources of infection are likely to be:
a) Direct
sick and dead rabbits
b) Indirect
fresh and frozen carcasses
rabbit skins, wool, products and by-products,
equipment,
contaminated food (particularly on small farms when diet is composed of green feed and forage),
manure/litter,
scavengers,
people (staff managing the disease, farmers, hunters, research workers, abattoir workers, press staff),
other animals (livestock, but mainly cats and dogs),
The infection can be transmitted either by direct or indirect contact with infected rabbits or their carcasses, excretions and contaminated objects. During the recent escape of the virus in Australia it has been suspected that the virus may be spread by insects and/or airborne dust particles.
Overseas experience indicates that epidemics of disease may occur throughout the year without marked seasonal differences, but there is no knowledge of the precise epidemiology of RCD in the New Zealand environment.
Clinical signs
Predominantly young and adult rabbits die suddenly following 6 to 24 hours fever accompanied by mild clinical signs. Most rabbits appear depressed by 18 hours after exposure to the virus and become progressively quieter and die with minimal apparent distress by 30 -40 hours. Early reports from the epidemic in China of nervous signs have not been a feature of the disease observed in other countries or in the laboratory. A few rabbits have a terminal nasal discharge as a result of acute pulmonary oedema and congestion. Up to 50% of rabbits at the age of 5-6 weeks and 99% of adult rabbits die within 24 hours of the onset of clinical signs.
Gross pathology
The most consistent post mortem findings in adult rabbits are a 4 to 8 fold-enlarged firm dark spleen, pale swollen liver, reddish speckled kidneys and wet lungs which failed to collapse. The trachea is filled with a clear stable froth, which becomes progressively more blood-stained in the hours after death and sometimes exudes from nostrils to superficially resemble terminal bleeding.
Rabbit calicivirus disease is an exotic disease - notify the authorities if you have the disease on your property
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