Infectious diseases are sometimes called contagious disease when they are easily transmitted by contact with an ill person or their secretions (e.g., influenza). Thus, a contagious disease is a subset of infectious disease that is especially infective or easily transmitted. Other types of infectious/transmissible/communicable diseases with more specialized routes of infection, such as vector transmission or sexual transmission, are usually not regarded as "contagious", and often do not require medical isolation (sometimes loosely called quarantine) of victims. However, this specialized connotation of the word "contagious" and "contagious disease" (easy transmissibility) is not always respected in popular use. COUNT 5
QSN1 When are infectious diseases called contagious diseases?  ANS1 when they are easily transmitted by contact with an ill person QSN2 What is a contagious disease a subset of? ANS2 infectious disease QSN3 What sets a contagious disease after from a standard infectious disease? ANS3 especially infective or easily transmitted QSN4 Diseases with vector transmission or sexual transmission don't often require what type of isolation? ANS4 medical QSN5 What is not always respected in popular use? ANS5 specialized connotation of the word "contagious"