On 7 Jun 2005, Rabbit Hemorrhagic Disease (RHD) was confirmed at a private residence in Vanderburgh county, Indiana by the Foreign Animal Disease Diagnostic Laboratory (FADDL) on Plum Island, NY. Specimens from these rabbits were positive for RHD antigen on ELISA, electron microscopy, and PCR. A FAD (Foreign Animal Disease) investigation was initiated on 3 Jun 2005 on a premises that raises rabbits primarily for sale to reptile owners as a food source for snakes.
The investigation revealed that many of the 200 rabbits on the premises suddenly died during the past 10 days. Less than a dozen rabbits had recently been purchased from Kentucky and introduced into the herd. An epidemiologic investigation has begun in Kentucky. The remaining rabbits are quarantined and will be euthanized and disposed of in accordance to State regulations. Cleaning and disinfection of the area will follow.
The Indiana epidemiological investigation is ongoing. APHIS, Veterinary Services (VS), the Indiana Board of Animal Health, and the Kentucky Department of Agriculture are working together to address this situation. VS (Veterinary Services) will assist the affected State in the euthanasia, cleaning, and disinfection of the premises. VS will continue to investigate reports of suspect RHD as part of its foreign animal disease surveillance program and will continue to diagnose suspect cases at FADDL.
The last known positive RHD case in the US occurred in a captive exotic animal facility in Flushing, New York in December 2001. Rabbit hemorrhagic disease (RHD) is a highly infectious viral disease of the European rabbit (Oryctolagus cuniculus). This is the species from which all U.S. domestic and commercial rabbits are derived. American cottontail rabbits and jackrabbits are not susceptible to infection. RHD is not known to harm humans or other animals. Once the disease is introduced into a rabbitry, it can spread rapidly, causing a high percentage of the rabbits to die. There is no treatment for the disease.
RHD damages the liver, intestines, and lymphatic tissue and causes terminal massive blood clots. The incubation period is about 24 to 48 hours. Predominantly, young adult and adult rabbits die suddenly within 6 to 24 hours of the onset of fever with few clinical signs. Fever may be as high as 105 F (40.5 C) but often is not detected until rabbits show terminal clinical signs. Most animals appear depressed or reluctant to move in the final hours and may show a variety of neurologic signs, including excitement, incoordination, paddling, and opisthotonos (abnormal position of the head due to spasms of the muscles at the top and back of the neck). Some affected rabbits may have a foamy nasal discharge. The death rate for RHD ranges from 50 to 100 percent.
RHD is caused by a highly contagious virus. The disease can be transmitted by contact with infected rabbits, rabbit products, rodents, and contaminated objects, such as cages, feeders, and clothing. The virus also may be carried short distances through moisture in the air. The risk of spread of RHD is higher when confined rabbits are in close contact with each other. Infected rabbits that recover may become carriers of the virus and may shed virus for at least 4 weeks.
To protect against introducing RHD into the U.S. rabbit population, owners and producers should avoid contact between their rabbits and imported rabbit meat, pelts, or other possibly contaminated objects from RHD-affected countries. To prevent the spread of the disease if it enters the United States, rabbit owners should prevent contact between healthy rabbits and infected rabbits and contaminated objects (e.g., cages, feeders, and clothing). Rabbits that appear healthy can be in the early stage of disease and later spread the disease. Recovered rabbits also appear healthy but can be carriers for at least 4 weeks and spread the disease to other rabbits. Owners should be cautious and isolate new rabbits and rabbits returning from shows for at least 5 days. If rabbits were exposed to RHD, isolation may help prevent spread to other rabbits. Clinical disease usually will be noticeable within 48 hours of infection.
If RHD is suspected, to prevent spread of the virus, rabbit owners should clean and disinfect all equipment. After thorough cleaning, rabbit breeders should use one of the following disinfectant solutions on equipment to inactivate the virus: 2-percent 1-Stroke Environ (Steris Corporation, St. Louis, MO), 0.5-percent sodium hypochlorite, or 10-percent household bleach.
No vaccine is legally available for use in the United States. Vaccine has been used in other countries. Vaccination often reduces the number of rabbits dying from RHD, but will not eradicate the disease. Rabbits vaccinated against RHD may become infected but not show signs of disease, thereby allowing spread of the virus as a carrier.
June 21, 2005
Original web page at ProMed Mail