“…These include influenza A (Tyrrell, 1952;Walker, Douglas, Leckie, Pines, and Grant, 1958), influenza B (Stark, Heath, and Curwen, 1965), respiratory syncytial virus (Sommerville, 1963;Carilli, Gohd, and Gordon, 1964), and Haemophilus influenzae (Mulder, 1956;Brumfitt, Willoughby, and Bromley, 1957;Lees and McNaught, 1959;Glynn, 1959;Morgan and Wood, 1965). The multiplicity of these reported agents suggests that acute exacerbations of chronic bronchitis may be associated with many infections prevalent in the community at the time.…”