Definition of "contagious disease" [con•ta•gious dis•ease]

• A disease communicable by contact with a patient suffering from it, or with some secretion of, or object touched by, such a patient. Most such diseases have already been proved to be germ diseases, and their communicability depends on the transmission of the living germs. Many germ diseases are not contagious, some special method of transmission or inoculation of the germs being required.

Gnu Collaboartive International Dictionary of English: licensed under The Code Project Open License (CPOL)

• "20 Scabies, a highly contagious disease in which parasitic mites cause intense itching, rashes, and infections, is an example of a nondelusional parasitosis."
• "The name syphilis was given to the disease in a Latin poem Syphilis sive morbus gallicus (1530), by Girolamo Fracastoro, who also elaborated a theory of contagious disease which in its fundamentals survived till the mid-nineteenth century."