At press time in late August, the Department of Agriculture's Foreign Animal Disease Diagnostic Laboratory confirmed the identification of the foreign rabbit-calicivirus disease on the basis of hemagglutination tests and electron microscopy from a rabbitry in Utah County, Utah. Prior to the outbreak being confirmed as RCV, the owner had allegedly sold and/or shipped rabbits to sites in Montana, Idaho, and Illinois.
The laboratory released a statement Aug. 23 stating that from the epidemiologic data gathered so far, it seems that the outbreak had been contained to the mentioned locations.
Utah state veterinarian Dr. Michael L. Marshall canceled all rabbit shows until the outbreak concluded, and ordered depopulation of the original infected herds.
In Yellowstone County, Montana, the three rabbits brought from the infected premises in Utah were euthanatized, and samples were taken. The preliminary test results for the three rabbits were negative, and final test results were pending.
The remaining rabbits on the premises were under quarantine. As a result of possible exposure at the Montana state fair, state veterinarian Dr. Arnold A. Gertonson placed 15 premises under quarantine as well.
In Idaho, movement restrictions were placed on a truck carrying approximately 3,600 rabbits, considered to be contacts. The rabbits were euthanatized, after which test results proved negative.
Mercer County, Illinois received 72 rabbits from the infected Utah premises. At press time, this area was under quarantine, and plans for depopulating the rabbits were under way.
Tracing in affected areas of the four states has revealed no other rabbit movements before quarantines were placed. The state departments of agriculture in Utah, Montana, Idaho, and Illinois were working with the USDA to address and control the situation.
Rabbit calicivirus, also known as viral hemorrhagic disease of rabbits, damages the liver, intestines, and lymphatic tissue and causes terminal, massive blood clots. Another U.S. outbreak of RCV occurred in April 2000.
The disease was classified as a foreign animal disease because the causative agent has never been previously confirmed in a rabbit within the borders of the United States. No vaccine is legally available for use in the United States.