CONTAGION

(Lat. contagies.) The propagation of specific diseases from person to person. Contagious poisons communicate the property of producing similar poisons: the smallpox is a characteristically contagious disease. By some writers the term has been limited to diseases requiring actual contact for their communication; but contagious matter appears often transmi ible by the air, hence the terms immediate and mediate contagion. Where diseases are propagated through the medium of the air, they are generally called infectious. [s. 292]