AVIAN ESCHERICHIA COLI INFECTION IN MEAT-TYPE CHICKEN: PREVALENCE AND PATHOLOGY

Abstract

Avian colibacillosis is considered the major bacterial disease in the poultry industry worldwide. This study was conducted to determine prevalence and pathology by avian pathogenic Escherichia coli (APEC) in broiler chicken. Various organs of affected broilers were checked for the E. coli infection. One hundred and forty commercial poultry farms were divided into seven age groups (A, B, C, D, E, F, and G). Group A (1st week), B (2nd week), C (3rd week), D (4th week), E (5th week), F (6th week), G (7th to 9th week). Investigations were conducted from day 1 until the marketing of birds based on clinical findings. A total of 2491 (23.71% of sick birds) dead birds were observed positive for E. coli infection. Three forms of infection were observed i.e. omphalitis, colisepticaemia, and colibacillosis at the rate of 1.55, 17 and 56.65%, respectively. Omphalitis was confirmed by microbial culture and revealed in only groups A and B with 76.24 and 23.76 respectively. While, Colisepticaemia was observed at the rate of 3.11, 6.74, 20.18, 29.63, 19.16, and 22.18 in groups B, C, D, E, F, and G respectively. Whereas Colibacillosis was noticed as 0.075, 3.35, 5.99, 19.20, 26.70, 16.11 and 28.55% in groups A, B, C, D, E, F, and G respectively. Petechiation of heart, kidney, and gizzard besides hemorrhagic enteritis, hemorrhagic tracheitis, and necrotic foci on the liver and caseous exudates in air sacs were the prime gross lesions noticed in colibacillosis. Microscopically, no lesion was observed in serosa, muscularis externa, and submucosa. However, loss of epithelial tissue and breaches in the mucosal layer of the small intestine were observed. Furthermore, characteristic pink and grayish colonies were observed in E. coli cultures on McConkey’s and Blood agar respectively.