Rabbit haemorrhagic disease: Biological pest control method to evolve as a transboundary disease

Abstract

Rabbit haemorrhagic disease (RHD), also known as viral haemorrhagic disease was a highly infectious and contagious disease affecting only European rabbits. It is caused by a host-specific calicivirus, called RHD virus (RHDV). The virus once used to control rabbit population in Australia is currently an important transboundary pathogen causing economic losses to the rabbit industry. RHDV appears to have evolved from a pre-existing avirulent rabbit calicivirus circulating in Europe, Australia and New Zealand. However, there is no conclusive proof. Emergence of RHDV was first detected in 1984 in China and then spread to Asia, Europe, Africa, Americas, Australia and New Zealand. With the evolution process, either by mutation or recombination or otherwise, there was antigenic drift in the original RHDV population (of 1984) leading to the development of antigenic variant RHDV2 (different serotype) that was detected in 2010, and is currently in circulation causing RHD with broader host susceptibility, and has almost replaced the parent serotype (RHDV1) of 1984. The death rate is observed to be 40-100% for RHDV1 and 5-70% for RHDV2. Rabbits vaccinated with RHDV1 are not protected from RHDV2 infection. The current review includes virology, pathology, epidemiology, diagnosis and prevention of RHD.