ABSTRACT
In his monograph "A Treatise of the Asthma" (l), published in 1698, Sir John Floyer wrote, "cannot remember the first Occasion of my Asthma; but have been told that it was a cold when I first went to school." Despite his experience and that of many asthmatics subsequently, the role of viral respiratory tract infection (VRTI) as precipitant of exacerbations of asthma has remained a subject of much debate. Indeed early investigators noted that viral infections lead to periods of anergy, as demonstrated by a reduction in delayed-type hypersensitivity responses, and concluded that viral infection, if anything, had a protective effect and would reduce the chances of an asthma exacerbation developing. In this chapter we will describe some of the early case reports that suggested that viral respiratory tract infections could lead to the development of exacerbations of asthma and then look at epidemiological and cohort studies that have investigated more fully their role. We will consider children and adults separately since the importance of VRTI in these two groups may differ.
