The Development of "Air Sac Disease"

Abstract

The terms sac and chronic respiratory (CRD) have been widely employed to designate a disease manifested by fibrinous pericarditis, perihepatitis, and thickening of the air sacs. It has been suggested that the disease had a very complex etiology since many agents have been isolated from accessions. Among the more important agents involved are the pathogenic Mycoplasma (also called pleuropneumonia-like organisms or PPLO), infectious bronchitis virus (IBV), Newcastle disease virus (NDV), and certain bacteria most frequently identified as Escherichia coli. This paper reports on methods of reproducing sac experimentally, and makes observations on its probable natural development in the field.