Epidemiological study of the relationship between Congo red binding Escherichia coli and avian colisepticemia.

An epidemiological prospective (longitudinal) study design was used to evaluate the association of Congo red positive Escherichia coli and avian colisepticemia. High and low risk exposure groups of chickens were identified at hatching, and placed in separate identical houses on the same farm. Approximately 14,000 birds were placed in each house for the seven week grow-out period, during which all birds which died were necropsied and cultured, together with a representative sample of birds which were culled weekly. The findings implicated Escherichia coli as the etiological agent of avian colisepticemia. A relative risk of 6.5 and attributable risk of 73.5% supported the hypothesis that the Congo red medium identifies a virulent form of Escherichia coli which causes airsacculitis-colisepticemia in poultry.