(b) Aerial dust particles coated with bacteria.

(c) Mixed, more than one bacterium or organism present in the system, they may enter together or one precede the other.

Contagious. A disease acquired from a direct contact with the sick.

Contagion. The spreading of a disease by direct or indirect contact.

(a) Direct contagion.

(b) Indirect contagion or mediate, as by a “carrier,” who is apparently in good health, but nevertheless carries disease and can convey it to other non-immune persons.

(c) By means of Fomites (hereafter defined).

Contagium. The virus or poison which transmits disease, such as the vaccine used in anti-smallpox vaccination, which in former years was obtained from the vacca or cow, now the calf is the source of supply.

Fomites. Any non-animate agents or substances that transmit contagion such as blankets, towels, handkerchiefs, or any articles which have been contaminated by the secretions or excretions of the sick.

Endemic. A disease which is permanently present in a people or district, it may become epidemic.