Introduction

A disease of chickens characterised by acute mortality, often with severe anaemia, caused by an adenovirus. A number of different sero-types have been isolated from disease outbreaks but they may also be isolated from healthy chickens.

The disease was first described in the USA in 1963 and has also been reported in Canada, the UK, Australia, Italy, France and Ireland. It has a course of 9- 15 days with a morbidity of 1-10% and a mortality of 1-10%. Infected birds remain carriers for a few weeks.

Transmission may be vertical or lateral and may involve fomites. Immunosuppression, for instance due to early IBD challenge or congenital CAV infection, may be important.

The virus is generally resistant to disinfectants (ether, chloroform, pH), and high temperatures. Formaldehyde and iodides work better. Curiously, many different sero-types have been isolated from different cases, but on the other hand many field cases show eosinophilic inclusions that do not appear to have adenovirus particles. Since adenoviruses are commonly found in healthy poultry, isolation alone does not confirm that they are the cause of a particular problem.

A form of the disease affecting birds under 3 weeks of age in Australia has been reproduced with sero­type 8 adenovirus.

Progeny of high health status breeding flocks appear to be at greater risk, perhaps because they have lower levels of maternal antibody.

Signs

• Depression.
• Inappetance.
• Ruffled feathers.
• Pallor of comb and wattles.

Post-mortem lesions

• Liver swollen, yellow, mottled with petechiae and ecchymoses.
• Kidneys and bone marrow pale.
• Blood thin.
• Bursa and spleen small.
• Microscopically - basophilic intranuclear inclusions.

Diagnosis

A presumptive diagnosis may be made on history and lesions. Confirmation is made on finding inclusions in the liver. The virus grows well in tissue culture (CEK, CEL).

Serology: DID for group antigen, SN for individual sero-types.

Differentiate from Chick anaemia syndrome, sulphonamide intoxication, Infectious Bursal Disease, vibrionic hepatitis, fatty liver syndrome, and deficiency of vitamin B₁₂.

Treatment

None. Soluble multivitamins may help with the recovery process.

Prevention

Quarantine and good sanitary precautions, prevention of immunosuppression.