part of process pathogen transmission process Process in which a pathogen is transmitted directly or indirectly to a new host. TRANS includes a sibling class of 'indirect' labeled 'direct', and these terms mirror standard definitions of 'direct transmission' and 'indirect transmission' in the literature. However, in the literature and in TRANS the definitions seem confused. For example, direct transmission is claimed to involve direct contact, yet respiratory droplet spread from a host - which plausibly involves a vehicle - is counted as direct rather than indirect transmission. We will follow standard use in part, adopting indirect transmission, but not direct, and defining a term for contact transmission. pathogenesis