ABSTRACT
Epidemiology is the study of disease transmission through the use of statistical and mathematical models. In this chapter the focus is on the epidemiology and dosimetry of airborne nosocomial infections. Relevant epidemiological statistics were summarized in the previous chapter and will not be revisited here. This chapter reviews transmission routes and summarizes the mathematics of airborne epidemiology and dosimetry, adapted for the hospital environment. These modeling tools will enable designers and infection control personnel to evaluate outbreaks or epidemics involving airborne transmission as well as surface-borne outbreaks. It must be reiterated here that the subject of airborne transmission is inextricably tied to surface transmission and that these subjects must be treated together in most cases. Obligate airborne transmission is thought to be a property of certain pathogens such as TB or in—uenza, but even these microbes may be transmitted via direct contact or contact with fomites. It will be shown herein that the infectious dose of any pathogen received at any entry point, whether the respiratory tract or an open wound, is the cumulative dose received by all routes, be they airborne, direct contact, or even endogenous migration. For each pathogenic species or each infection, one route may predominate but no routes should be neglected.
