The Effects Of Calicivirus Essay, Research Paper

What are the effects of Calicivirus?

As rabbit calicivirus kills rabbits quickly and the rabbits die quietly, there are usually no obvious signs of disease in a rabbit that has died from the virus. Some signs may be asessed but reliable diagnosis of the disease can only be made from lab tests on a piece of rabbit liver or spleen.

Possible indications of the disease

+ The coat and body of the rabbit appear in good condition with no outward signs of disease;

+ Watery fluid may run from the nose and mouth – this will be blood stained if the rabbit has been dead for more than about 12 hours;

+ The rabbit’s liver may appear pale and swollen (friable);

+ The spleen will be dark and enlarged at least two-fold;

+ The kidneys may appear dark and enlarged.

What was the success of release in Australia?

The initial impact of rabbit calicivirus in many arid areas of Australia has been a large drop in rabbit numbers. In parts of Western Australia, Northern Territory and South Australia rabbit populations fell by about 95% within a few weeks of being affected by the virus. In other areas, the results have been more unsuccesfull and more research is needed to understand how the virus operates in different land systems and climatic conditions.

How does the virus spread?

The virus mainly spreads in two ways:1 ’spotting’ where it jumps long distances via a vector (such as an insect) is involved and 2. ‘infilling’ where it is transmitted from rabbit-to-rabbit via contact with infected rabbits or their faeces. The rate of spread seems to be affected by climatic conditions. More research is being conducted to better understand how the virus is transmitted.

Where was it tested and released?

Australian trials started in March 1995 on Wardang Island. These were designed to provide more information about the effectiveness of the virus including the impact and persistence of the virus and its rate of spread between and within warren systems. In a trial in September 1995, the virus spread through the quarantine area. The trial was terminated forthwith and all rabbits in the quarantine area were culled. On 16 October, laboratory tests confirmed that rabbits at Point Pearce on the mainland had died of rabbit calicivirus disease.

After the approval of the use of the virus as a biological control against rabbits,

280 release sites were chosen and divided amongst all States and Territories:

NSW 50 QLD 50 ACT 5

VIC 50 WA 40 TAS 5

SA 50 NT 30