Turkey Haemorrhagic Enteritis: Australian Situation

Turkey haemorrhagic enteritis (HE) is caused by a group II avian adenovirus known as Haemorrhagic Enteritis Virus (HEV). HE is an acute disease of young growing turkeys with a sudden onset of depression, bloody faeces and a potentially high death rate (Pierson and Fitzgerald, 2008) but HEY may be more important as a cause of subclinical immunosuppression, splenomegaly and increased E. coli infections. An indistinguishable virus causes marble spleen disease (MSD) in pheasants and avian adenovirus splenomegaly (AAS) in chickens and these viruses are able to transmit between the host species. HE is controlled by live virus vaccination with avirulent strains of the virus in most major turkey producing regions of the world, but not Australia although a relatively avirulent strain HEV086 was isolated 30 years ago. HE is present in Australia (Tham and Critchley 1981; Tham and Thies 1988; Arzey and Cross 1990) with Tham and Critchley (1981) describing outbreaks in 7-8 week old broilers with mortality of 0.5-1% over a week. HEY is also considered to be a historical cause of loss of 01 production, illness and mortality in commercial turkey operations typically causing splenomegaly, mortality and increased E. coli infections at around 8-12 weeks of age. The recent status of the disease in Australia is uncertain with few diagnostic tools readily available to investigate it. With funding from the Poultry CRC we sought to • Develop or obtain suitable serological and molecular tests for HEY • Use these in field studies to assess the prevalence and importance of HEV • Develop a vaccine for HEY based on strain HEV086