imports from China, and by 1986, had made its way to Italy, subsequently spreading across Europe. The Americas experienced their first outbreak in 1988 in Mexico, linked to rabbit products imported from China, though Mexico successfully curbed the disease by 1992. Today, RHD remains a threat in regions inhabited by European rabbits, causing deadly outbreaks across almost all continents.
Transmission
Rabbit Hemorrhagic Disease Virus (RHDV) can be transmitted through oral, nasal, conjunctival, and parenteral routes, with blood-feeding insects identified as effective mechanical vectors for the disease. Transmission can occur directly through contact with an infected rabbit, which may release the virus via its secretions and excretions. Indirect transmission is also possible through contaminated objects such as food, bedding, water, clothing, cages, and equipment, or via vector-borne pathways involving scavenging mammals, birds, and insects. The primary entry points for the virus are believed to be within the upper respiratory and digestive tracts. In natural settings, the fecal-oral route is considered the most common pathway for spreading the disease.
Clinical signs
All domestic rabbits (Oryctolagus cuniculus) are at risk of RHD infection. RHDV2 poses no risk to humans, livestock, or other pets. There are four primary infection forms of RHD, each displaying similar clinical signs that do not vary significantly across different viral strains. In the extremely rapid peracute form, rabbits often show no clinical signs until terminal vocalizations, collapse, and death occur within 12 to 36 hours.
The slightly slower acute form can exhibit a broader spectrum of symptoms, including bleeding from the mouth, nose, or rectum, fever, difficulty breathing, eye hemorrhages, bloody feces, and jaundice due to anemia and coagulation issues triggered by the virus. The subacute form presents with the same symptoms but in a milder form, offering a chance of survival. Neurological symptoms may include loss of coordination and seizures, along with depression, lethargy, and decreased appetite.
Diagnosis
Diagnosis of rabbit hemorrhagic disease is typically confirmed by performing a post-mortem examination, revealing characteristics such as an enlarged and pale liver indicative of the disease. For living rabbits, molecular diagnostic techniques like PCR (Polymerase Chain Reaction) or ELISA (Enzyme-Linked Immunosorbent Assay) can be utilized to confirm the presence of the virus. It's important to note, however, that some of these tests might not differentiate between the original RHDV strain and its variant, RHDV2.
Treatment and Prevention
At present, rabbit hemorrhagic disease has no cure. While supportive care can offer some help, prevention through vaccination is the most effective strategy. Hyperimmune antiserum might work if administered before clinical signs develop, but it becomes ineffective once symptoms are present. Vaccination is a viable preventive measure for domestic rabbits. However, due to the vast population of wild rabbits, vaccinating them is currently not economically viable.
Note
Bioguard’s Qmini PCR can detect RHDV DNA in 90 minutes at your clinics using blood as samples.
