The general discussion of the ways in which contagious diseases are
spread at the beginning of this article covers also diphtheria. The
germs are in the secretions from the throat and nose. About one
person out of every ten who is about a case of diphtheria becomes a
carrier. Carriers play a large part in the spread of this disease.
When an outbreak occurs in a school, it can usually be traced to one
or more healthy carriers among the pupils or even the teachers. This
is determined by making cultures from all the throats and noses.
Diphtheria may be introduced into a community by a carrier who comes
from outside.