author(s)
S. K. Boro, D. C. Pathak, G. K. Saikia and M. Buragohain

abstract
During the period of this investigation from July 2016 to June 2017, a total of 268 carcasses of birds irrespective of the age, breed and sex were collected from organized and unorganized farms in and around Guwahati city. In bacteriological isolation of Escherichia coli using MacConkey agar (MLA) and Eosin methylene blue (EMB), 46 cases were found positive for colibacillosis. The overall prevalence of colibacillosis was recorded as 17.16%. The different pathological conditions results from colibacillosis observed in the present study were colisepticaemia (n=23), enteritis (n=13), oophoritis (n=8) and omphalitis (n=2). On the basis of age group, the highest prevalence of colibacillosis was recorded at the age group of 3-6 weeks compared to the other age groups. Again highest prevalence of colibacillosis in urban and semi-urban areas were recorded at 38.46 percent and 50 percent respectively in 3 to 6 weeks of age group.