Prevalence and histopathological investigation of colibacillosis in Broiler chickens in the Rajshahi District, Bangladesh

Avian colibacillosis is regarded as a serious bacterial disease in the poultry industry worldwide. Common bacteria known as Escherichia coli (E. coli) are naturally present in birds' digestive tracts and, consequently, in their surroundings. A strain of E. coli known as Avian Pathogenic Escherichia Coli (APEC) is capable of causing a clinical illness. Large financial losses result from colobacillosis in commercial broiler farms because of a comparatively high death rate and productivity loss. In the present study, a total of 300 broilers of 8 farms were examined and among them 170 (56.67%) were diagnosed as infected with any form of colibacillosis and 42 sick and dead birds (different organs) were collected from necropsy cases. The most frequent gross lesions of colibacillosis were cloud and thickened air sac, omphalitis, pericarditis, perihepatitis, peritonitis, colisepticemia, enteritis. The pericardium of the heart's thick fibrous layer, telangiectasis, blunting and sloughing off of the villus, and persistent passive congestion were the microscopic lesions of these illnesses, infiltration into the intestinal lamina propria. Average prevalence of colibacillosis, on the basis of age was higher (67.32%) in age group 0-2 weeks and lower in 4 weeks (0.2 %). The results obtained during the study period revealed that the higher prevalence of colibacillosis was in winter season (68.90%) and lower in summer season (41.91%). So, age and winter season was the risk factors of colibacillosis. Considering the factor, colibacillosis causes high mortality and winter season was the main risk factor and involved other factor in broiler at Rajshahi district.