Rabbit haemorrhagic disease

Rabbit haemorrhagic disease (RHD) is a highly contagious and acute fatal hepatitis of Leporids, caused by a calicivirus (genus Lagovirus). Up to 2010, all RHD viruses (RHDV) isolated belonged to one of the previously identified six genotypes (G1–G6), among which the G6 is an antigenic subtype (RHDVa). In 2010, an additional RHDV, phylogenetically and antigenically distinct from RHDV, emerged in Europe and was called RHDV2. Another lagovirus, called the European brown hare syndrome virus (EBHSV), causes a similar disease in hares (Lepus europaeus, L. timidus and L. corsicanus). RHD is characterised by high morbidity and a mortality of up to 90%. Infection mainly occurs by the oral route. Transmission follows contact with infected rabbits or via indirect contact with mechanical vectors (including insects, birds and humans) or contaminated tools and equipment. The incubation period of RHD varies from 1 to 3 days, and death usually occurs 12–36 hours after the onset of fever. The main clinical manifestations of the acute infection are nervous and respiratory signs, apathy and anorexia. In rabbits younger than 4–6 weeks, the RHDV/RHDVa infection course is subclinical, but when the causative agent is RHDV2, clinical signs and mortality are observed even in young animals from 7 to 15 days of age onwards. Indirect control of the disease is easily achieved by vaccination. RHDV has never been reported in humans and other mammals.