Are you asking where the Corynebacterium diphtheriae bacteria are present when they are not living in a persons sinuses?
Corynebacterium diphtheriae bacteria are mainly present in the spring and winter months and Human carriers are the main reservoir of infection. so basically you can get them from “human carriers” of the disease, people who harbour the bacteria but don’t get infected by them. They are also linked to zoonotic transmission to humans and has been most frequently seen in agricultural communities associated with livestock, so you can get them from some infected farm animals, particularly livestock. When wanting to find such info. in a search engine about a particular disease, firstly find the bacteria’s name that cuases the infection and search for its Pathophysiology. It should give you the answers that you need.
