ABSTRACT
Etiology is the study of the detailed factors of infectious disease. The etiology of airborne pathogenic disease is multifaceted, involving airborne transport of pathogens, surface contamination and resuspension of fomites, hand contact, direct contact with droplets, and inhalation in the case of respiratory pathogens. In the case of nonrespiratory pathogens, shedding of endogenous bacteria and pathogens is the initial route of aerosolization. A number of these elements of etiology have been introduced in previous chapters, where a distinction was made between airborne transmission and airborne transport, the former term referring to the causative route of infection while the latter refers simply to the physical transport of a microbe via air currents, such as when spores enter a hospital environment. Another concept of use in this chapter is the classiŸcation of airborne pathogens into seven categories, these being respiratory infections, nonrespiratory infections, SSIs, burn wound infections, immunocompromised infections, pediatric infections, and nursing home infections. The etiologies of these categories are addressed in the following sections and the modes of transport are summarized in Table 5.1. These are the primary or most common modes because virtually every mode of transport may contribute to each type of infection. Each of the airborne modes of transport will be discussed in the following sections after a review of aerosolization. The modes of droplet spray, hand contact, and ingestion were discussed in previous chapters or are self-explanatory and need no further discussion.
