Clinical and Laboratory Diagnoses of Common Bacterial Diseases of Broiler and Layer Chickens

The study was undertaken with a view to compare clinical and laboratory diagnoses of various bacterial diseases of poultry during the period from March 2009 to February 2010 in the laboratory of the Dept. of Microbiology and Hygiene, Bangladesh Agricultural University (BAU), Mymensingh. A total of 135 sick and dead chickens (47 broilers and 88 layers) were collected from 12 different poultry farms (4 broilers and 8 layers) of Mymensingh and Gazipur districts which were subjected for clinical followed by laboratory diagnosis. Clinical diagnosis was made on the basis of clinical history, clinical signs and postmortem findings of the affected birds whereas; confirmatory diagnosis was made by using cultural examination, Gram’s staining and different biochemical tests. In this study, out of 47 broilers, 16 (34%) chickens were clinically diagnosed as colibacillosis, 11 (23.40%) as salmonellosis and 2 (4.25%) as fowl cholera. In the same way, out of 88 layer chickens, 28 (31.82%) were diagnosed as colibacillosis, 16 (18.18%) as salmonellosis and 11 (12.50%) as fowl cholera. In laboratory, out of 47 suspected broiler chickens, 12 (25.53%) chickens were diagnosed as colibacillosis, 7 (14.89%) as salmonellosis and 0 (0%) as fowl cholera. Correspondingly of the 88 layer chickens 22 (25%) were diagnosed as colibacillosis, 11 (13.64%) as salmonellosis and 8 (9.09%) as fowl cholera. So the findings concluded that clinical diagnosis is not always accurate like laboratory diagnosis because in most cases clinical history, clinical signs and post-mortem lesions of different bacterial diseases including mixed infections are almost similar to other related diseases and it is recommended to confirm laboratory diagnosis before treatment of the diseases.