Providing Information About Rabbits

CEI Impact Worksheet Iowa April 2000

April 13, 2000 - Statement from: Patrick G. Halbur DVM, PhD, Iowa State Univeristy
April 19 2000 - Statement from: Dr. Alfonso Torres, Administrator, Veterinary Services, USDA (Via Peter Cowen)
May 25, 2000 - Statement from: Barbara Bischoff, USDA

Emergency Management Warning:
 

Viral Hemorrhagic Disease CONFIRMED in USA

On April 7, 2000, Rabbit hemorrhagic disease was confirmed in the USA, killing 25 out of 27 rabbits in a backyard rabbitry in Iowa. This is the first case of Viral Hemorrhagic Disease to be reported in the USA. The remaining two rabbits were euthanized.
 

RABBIT HEMORRHAGIC DISEASE VIRUS - USA (IOWA)
 

ProMED-Mail, Rabbit Hemorrhagic Disease Virus - USA (Iowa), ProMED-Mail 2000;20000413.0527, <http://www.promedmail.org>, Accessed 03 January 2006.

Date: 13 Apr 2000
From: Patrick G. Halbur DVM, PhD <pghalbur@iastate.edu>

Rabbit Calicivirus Disease (also known as Viral Hemorrhagic Disease of Rabbits) [caused by rabbit hemorrhagic disease virus, a calicivirus] was confirmed in a group of 27 rabbits in Crawford County, Iowa. As of April 6th, 25 of 27 rabbits had died and the remaining 2 were euthanized on April 8th. The rabbits were Palominos and California Whites. The premises is quarantined and the disease appears to be contained on the premises.

The first rabbit, one allowed to roam near the house, died on 9 Mar 2000. Rabbits housed in hutches started dying on 16 Mar 2000.

The source of infection has not been determined. There have been no introductions of rabbits onto the premises in the last 2 years. August 1999 was the last time rabbits left the farm and returned. In January 2000, six rabbits, all healthy and greater than 2 months old, were sold. There are no known premises with rabbits in the near vicinity. Veterinary Services and the Iowa Department Agriculture and Land Stewardship are continuing the investigation.

A private veterinarian forwarded samples to Iowa State University Diagnostic Laboratory on 22 Mar 2000. Microscopic examination revealed severe acute periportal hepatic necrosis and hemorrhage, pulmonary edema, and fibrinous thrombi in renal glomeruli. Rabbit calicivirus or toxic hepatopathy was suspected based on the clinical history and microscopic lesions. Cultures for _Pasteurella multocida_ and other bacteria were negative. A mycotoxin screen of the feed was negative.

On 24 Mar 2000, a second rabbit was submitted with similar lesions. The state and federal officials were notified on 27 Mar 2000, and a foreign animal disease investigation began immediately. Epidemiologic information was collected and samples were sent to the USDAs Foreign Animal Disease Diagnostic Laboratory (FADDL). FADDL suspected rabbit calicivirus disease based on hemagglutination (HA) tests and electron microscopy. FADDL forwarded samples to Spain for confirmation; the laboratory in Spain further confirmed the diagnosis by polymerase chain reaction assay.Rabbit calicivirus was first reported in 1984 in the Peoples Republic of China. From 1985-1986 it spread through the domestic and wild rabbit populations in continental Europe. The first report of the virus in the Western Hemisphere was in Mexico City in 1988. Mexico was successful in eradicating the virus by 1992. Recent outbreaks of rabbit calicivirus disease have occurred in Australia (1995), New Zealand (1997) and Cuba (1997). In 1995, as a result of a laboratory accident in southern Australia, the virus escaped and killed 10 million rabbits in 8 weeks. Rabbit Calicivirus Disease is a disease of the European rabbit (_Oryctolagus cuniculus_). This is the species from which all U.S. domestic and commercial rabbits are derived. Rabbits native to North America (cottontail rabbits and jackrabbits) do not develop clinical disease and are not susceptible to rabbit calicivirus.

Humans and other mammals are not infected by the rabbit calicivirus.

Rabbit calicivirus is a highly contagious virus transmitted by direct contact with infected rabbits or indirectly by contact with objects contaminated with virus. Morbidity is often near 100% and mortality 60-90%. Infection results in a peracute febrile disease of domestic rabbits causing hepatic necrosis, enteritis, and lymphoid necrosis followed by massive coagulopathy resulting in hemorrhages in a variety of organs. Rabbits die acutely within 6 to 24 hours of the onset of a fever with few clinical signs.

If you have any questions please contact USDA, APHIS, Veterinary Services, Emergency programs staff at 301-734-8073, 800-940-6524, or EMOC@USDA.GOV. A Factsheet, an Impact Worksheet, and a Questions and Answers document can be accessed on the APHIS website: <http://www.aphis.usda.gov/>
--
Patrick G. Halbur DVM, PhD
Iowa State University
Veterinary Diagnostic Laboratory
<pghalbur@iastate.edu>

 

RABBIT HEMORRHAGIC DISEASE VIRUS - USA: OIE REPORT

ProMED-Mail, Rabbit Hemorrhagic Disease Virus -USA: OIE Report, ProMED-Mail 2000;20000419.0571, <http://www.promedmail.org>, Accessed 03 January 2006.
 

Date: 19 Apr 2000
From: Peter Cowen <Peter_Cowen@ncsu.edu>
Source: OIE Disease Information 14 Apr 2000.
<http://www.oie.int/info/AIS_49.HTM>

[Below is the official text to OIE from Dr. Torres. It contains a few additional details over and above the excellent earlier posting from Patrick Halbur referenced above. The outstanding questions at this point - how did these bunnies get the virus and will we ever know the genesis of the outbreak? - Mod.PC]

Text of a fax received on 12 April 2000 from Dr Alfonso Torres, Deputy Administrator, Veterinary Services, United States Department of Agriculture (USDA), Washington, DC:

Report date: 10 Apr 2000.

Nature of diagnosis: clinical, postmortem and laboratory.

Date of initial detection of animal health incident: 31 Mar 2000.

Estimated date of first infection: 7 Mar 2000.

Description of affected population: all rabbits on the affected premises, which is in a rural location, were being raised for the purposes of exhibition. They were all Palominos or California Whites.

Total number of animals in the outbreak:

susceptible 27
cases 25
deaths 25
destroyed 2
slaughtered 0

Diagnosis:

- The first rabbit, one allowed to roam near the house, died on 9 Mar 2000.
- Rabbits housed in hutches started dying on 16 March.
- On 22 March, a private veterinarian forwarded samples to Iowa State University Veterinary Diagnostic Laboratory. Rabbit haemorrhagic disease (RHD) or toxic hepatopathy was suspected based on the clinical history and microscopic lesions in the liver.
- On 24 March, a second rabbit was submitted with similar lesions.
- The State and Federal offices were notified on 27 March and a foreign animal disease investigation began immediately. Epidemiological information was collected and samples were sent to the USDA's Foreign Animal Disease Diagnostic Laboratory (FADDL), Orient Point, State of New York.
- On 31 March FADDL tentatively diagnosed RHD based on haemagglutination test on liver homogenate from inoculated rabbits and electron microscopy.
- FADDL forwarded samples to the National Institute for Agrarian Research (INIA), Madrid, Spain, for confirmation.
- Confirmation of RHD was received from INIA on 7 April, based on polymerase chain reaction tests.

Epidemiology:

A. Source of agent / origin of infection: despite extensive investigations, the source of the introduction of the virus onto the site has not yet been identified.

B. Mode of spread: spread has been confined to one premises. Spread on that premises has been by close contact with infected rabbits and indirect spread by materials contaminated with virus is also suspected.

C. Other epidemiological details:

- There have been no introductions of rabbits onto the premises for the last two years.
- The first week of August 1999 was the last time rabbits left the farm and returned.
- In January 2000, six rabbits, all healthy and over two months old, were sold.

Control measures during reporting period:

- The affected premises are quarantined by the State authority.
- The State authority destroyed the remaining two rabbits on 8 Apr 2000.
- Cleaning and disinfection will be controlled by the State authority.
- Premises with rabbits in the near vicinity are being located, and owners are being contacted to determine whether similar circumstances have occurred elsewhere.
--
ProMED-mail
e-mail: promed@promedmail.org

 

RABBIT HEMORRHAGIC DISEASE VIRUS - USA (IOWA) (02)
 

ProMED-Mail, Rabbit Hemorrahgic Disease Virus - USA (Iowa) (02), ProMED-Mail 2000; 20000526.0836, <http://www.promedmail.org>, Accessed 03 January 2006.


Date: Thu, 25 May 2000 15:44:39 -0400
From: Barbara Bischoff <Barbara.A.Bischoff@usda.gov>

APHIS' Emergency Management Operations Center (EMOC) announced on May 12 that the investigation of RCD in rabbits in Crawford County, Iowa, was closed. There have been no new cases of RCD [sic: rabbit hemorrhagic disease, RHD; the etiologic agent of which is rabbit hemorrhagic disease virus, RHDV - Mod. CHC]. An extensive epidemiological investigation failed to determine how the rabbits were infected.

USDA's Foreign Animal Disease Diagnostic Laboratory (FADDL) provided the following information about the characterization of RCV/USA/Iowa/2000. RT-PCR products of a 1993 FADDL experimental case of rabbit calicivirus infection (from field material of Mexico 1989) were sequenced. The Iowa isolate is significantly different from the virus that caused the outbreak in Mexico in 1989, and is most similar to the European isolates from the late 1980s. Additional support for an Italy/Germany origin is the monoclonal antibody reactivity profile that compares the RCV/USA/Iowa/2000 to strains that occurred in those two European countries in 1996-1997. This variant is known in Europe as "RHDVa". FADDL thanks ARS colleagues at Plum Island for their support in sequencing the PCR products of the Mexican isolate and colleagues of the Brescia lab in Italy for the monoclonal antibody profiles.

Dr. Kevin Petersburg, area veterinarian in charge (AVIC) for Illinois, provided a summary of the investigation (see below).

/s/ Joseph F. Annelli

Chief Staff Veterinarian, Emergency Programs
USDA, Animal and Plant Health Inspection Service, Veterinary Services
4700 River Road, Unit 41
Riverdale, MD 20737-1231
TEL: (301) 734-8073

Report from Dr. Kevin Petersburg, Iowa AVIC

On March 27, 2000, a veterinarian from the ISU Diagnostic Laboratory called the Area office of USDA, APHIS, VS to report that a rabbit that he had necropsied had liver damage that appeared consistent with Viral Hemorrhagic Disease of Rabbits, also known as Rabbit Calicivirus Disease (RCD) [sic: see above].

Veterinary Services personnel picked up the tissues and slides from this case and sent the samples to the USDA, Foreign Animal Disease Laboratory at Plum Island, New York.

The Foreign Animal Disease Laboratory and a laboratory in Spain confirmed that the rabbits were infected with Rabbit Calicivirus Disease. The rabbits were raised on an acreage in Crawford County, Iowa. The acreage was quarantined by the Iowa Department of Agriculture and Land Stewardship by the order of the State Veterinarian. Some of the rabbits were housed in hutches and some were allowed to run free. The free-roaming rabbits were fed pellets on the ground in front of the rabbits in hutches. The free-roaming rabbits were the first to get sick and die. The rabbits in hutches were affected soon after that. The rabbits tended to show no clinical signs before the owner found them dead. Twenty-five of twenty-seven rabbits died from March 9 - March 30. The two remaining rabbits were euthanised by Veterinary Services personnel and the carcasses were incinerated at the National Veterinary Services Laboratory in Ames, IA. The hutches and a building that housed a couple of the hutches were burned and the ashes were buried under the supervision of the Iowa Department of Agriculture and Land Stewardship.

The acreage remains quarantined until such time as the remaining virus on the acreage would likely have been inactivated by exposure to the natural elements. An extensive epidemiological investigation has failed to determine how the rabbits got infected. The investigation included questions about any visitors to the acreage who own rabbits (one), any shows in which the rabbits may have participated (none since August 1999), any visits to other rabbit sites by the owner or his daughter (none), any sales of rabbits (a few sold and slaughtered in January), and the source of feed for the rabbits and the source of hutches and utensils for the rabbits. All premises within 1 mile of the acreage were visited and no domestic rabbits were found. Local veterinary clinics were contacted and none had seen sick rabbits recently. Only one individual who had contact with the rabbits also raised rabbits, and his rabbits were healthy until May 2, 2000 when one [of his] rabbits died. Tissues from the rabbit were sent to the Foreign Animal Disease Laboratory at Plum Island, New York; RCD was ruled out. The persons who buy feed at the same facility as the owner of the positive premises were contacted; their rabbits are all healthy. Other businesses that sell rabbit feed also were contacted for a list of clients. None of the clientele that were contacted had sick rabbits. The total number of businesses and individuals contacted was approximately 47.

The following contacts were made to notify people that RCD was found in Iowa: the Office of International Epizootics (OIE), the American Rabbit Breeders Association, the House Rabbit Society, Kind Planet, the Rabbit Industry Council, U.S. licensed biologics manufacturers and rabbit breeders, the American Association of Veterinary Laboratory Diagnosticians, and the American Veterinary Medical Association. State veterinarians and Area Veterinarians in Charge also were provided with information for further dissemination within their states. The Iowa Veterinary Medical Association, the Iowa State University Extension Service, cooperative extension offices and 4-H officers were provided with information.Information was also posted on the USDA, APHIS website. No additional cases of RCD have been reported at this time. Although we continue to encourage people to report possible new cases of RCD to our office, we are considering the current investigation closed at this time.
--
ProMED-mail
e-mail: promed@promedmail.org

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