Pathological changes associated with an outbreak of colibacillosis in a commercial broiler flock

Escherichia coli infection was diagnosed in 5-week old broiler chickens raised intensively on a medium-sized commercial farm in Gaube-Kuje, Abuja, Nigeria. Signs of weakness, depression and inappetance with ruffled feathers and pasted vents were reportedly observed in affected birds within the flock. Detailed post mortem examinations revealed diffuse splenomegaly and hepatomegaly with multifocal greyish areas on their surfaces while the diffusely enlarged kidneys were congested with mottled pale appearance. Histopathologically, the liver of affected broilers showed diffuse congestion, multifocal coagulative necrosis and cellular infiltration. Generalized perivascular and inter-septal oedema and haemorrhage were observed in the lungs of affected broilers with generalized lymphocytic depletion within the spleen as well as locally extensive congestion and haemorrhage within the kidney, and cellular infiltration and necrosis within heart musculatures. Microbiological evaluation of liver samples yielded pure E. coli growth only. A diagnosis of colibacillosis, especially colisepticaemia, was made with appropriate treatment based on culture and sensitivity test result involving Levofloxacin(R). The client was consequently advised to guard against possible predisposing factors as control and preventive measures for the disease outbreak on the farm.Keywords: Broiler chickens, Colibacillosis, Gross pathology, Histopathology, Natural infectio