Clinicopathological Characteristics of Acute Inclusion Body Hepatitis Outbreak in Broiler Chickens in Iran

An outbreak of inclusion body hepatitis was noticed in 20% of the population of a flock of 20000 broiler chickens. The affected 14-day-old birds experienced 10% mortality during a period of one week. On 39 and 44 days of age, clinical infectious bursal disease and Newcastle disease with 5% and 15% mortalities occurred in the flock, respectively. Clinical signs of affected birds included depression, leg weakness and mild watery droppings. Grossly, only the affected liver was a friable and enlarged organ associated with petechial haemorrhages and multifocal gray-white to yellowish necrotic areas. Histopathologically, multifocal to coalescing necrosis of hepatocytes, remarkable large basophilic intranuclear inclusion bodies were diagnosed. In the present study, it seemed that the causative agent had produced acute disease without predisposing factors and it could be suggested that resulting immunosuppression was the trigger mechanism for subsequent infectious bursal disease (IBD) and Newcastle disease (ND) outbreaks.