Source of Communication
There are two recognized principal sources of communicable dis-ease common to man, namely, man himself and the lower animals. It is interesting to note that most of the so-called communicable dis-eases are peculiar to man alone. They are not found in the lower animals except as they are communicated by man for experimental purposes. It is true that domesticated animals are more susceptible to dis-ease than wild animals.
From the standpoint of hygiene there must be a distinction made between the source of infection and the media of conveyance. Man and animals are considered the main sources of infection. Environment is regarded a source of infection. It is maintained that water, food, air, and soul form a media for conveyance, but they are not considered sources of infection. Rosenau, one of the leading hygienists, states that “most of the microörganisms causing the communicable dis-eases of man are frail and soon die in our environment, as in the air, soil or water.” Notwithstanding this fact, some still maintain that these frail little germs cause dis-ease.