part of realized in characteristic of inheres in process role anatomical entity infectious agent portal of entry role Albert Goldfain Lindsay Cowell A role borne by an anatomical entity in virtue of the fact that it serves as the site through which an infectious agent enters a host. Alexander Diehl The role is realized in a process by which an infectious agent enters a host. infectious agent portal of exit role disinfectant role antiseptic role primary infection role secondary infection role host role source of infection role transmission process