Big Liver and Spleen Disease present in UK poultry flock

Latest figures show a mixed message on the disease status of the UK poultry flock with diagnoses of Marek’s Disease down, Spotty Liver up and the discovery of the virus that causes Big Liver and Spleen Disease.

These are the findings reported in the Veterinary Laboratories Agency’s (VLA) latest endemic disease surveillance bulletin, which covers the period January to April 2007.

Big Liver and spleen disease was first identified in broiler breeders in Australia in the 1980s and is now known to be caused by infection with avian hepatitis E. However, the current status of the UK flock is unknown, so the VLA set out to survey 13 layer flocks and 17 broiler breeder flocks across the UK, testing a total of 683 samples.

Results revealed the virus was present in three layer and two broiler breeder flocks. Two of the layer flocks had a history of poor egg production and one of the broiler breeder flocks had a history of both poor egg production and increased mortality.

However, the VLA stressed that further work is needed before any link between poor performance and the virus, to rule out other possible common causes of such problems.

The VLA bulletin report also highlighted that the number of Marek’s disease diagnoses were lower than the same period in the previous year at about 5.5% of submissions. In contrast, there has been an increased incidence of Spotty Liver Syndrome.

Spotty Liver had previously been known as Avian Infectious Hepatitis/Avian Vibrionic Hepatitis. It was seen a lot in the 1980s when a number of cases followed heavy worm burdens, but had all but disappeared a few years later.

The condition can be seen clinically with up to 10% morbidity characterised by lethargy and depression within birds. In some cases, production drops in excess of 35% have been experienced with up to 15% mortality.

While the causes are poorly understood, it can be partly prevented by controlling gut parasites, including coccidian and worms, which cause gut damage making birds more susceptible to secondary bacterial infection.

Surveillance Report Avian is a quarterly report issued by the VLA which monitors trends in the major endemic diseases. It is compiled using disease data gathered by the network of VLA regional laboratories