Viral haemorrhagic disease of rabbits in the People's Republic of China: epidemiology and virus characterisation.

Viral haemorrhagic disease (VHD) is a new and severe infectious disease of rabbits, with a high rate of morbidity and mortality. The disease occurs throughout the year, affecting only adult rabbits and not other domestic animals, fowls or laboratory rodents. The transmission is horizontal, by direct or indirect contact, and through all routes. There is no evidence of congenital infection or biological vectors. The causative agent, viral haemorrhagic disease virus (VHDV), is present in all tissues, excretions and secretions. It is an icosahedral and nonenveloped parvo-like virus. The genome, as determined by classical methods, high performance chromatography and in vitro synthesis of double-stranded DNA, is linear, single-stranded DNA. VHDV can agglutinate human erythrocytes at very high titres, irrespective of blood groups, and has a stable reaction to many physical and chemical factors. VHDV has been adapted to grow on rabbit kidney cell strain (DJRK) culture and to produce cytopathic effect (CPE). Inactivated cell culture can protect inoculated rabbits against virulent VHDV. The disease is now effectively controlled in the People's Republic of China, but has not yet been completely eradicated.