Contagious disease

Originally, the term referred to a contagion or disease transmissible only by direct physical contact. In the modern-day, the term has sometimes been broadened to encompass any communicable or infectious disease. Often the word can only be understood in context, where it is used to emphasize very infectious, easily transmitted, or especially severe communicable diseases. In 1849, John Snow first proposed that cholera was a contagious disease. == Effect on public health response ==

to prevent disease transmission Most epidemics are caused by contagious diseases, with occasional exceptions, such as yellow fever. The spread of non-contagious communicable diseases is changed either very little or not at all by medical isolation of ill persons or medical quarantine for exposed persons. Thus, a "contagious disease" is sometimes defined in practical terms, as a disease for which isolation or quarantine are useful public health responses. Some locations are better suited for the research into the contagious pathogens due to the reduced risk of transmission afforded by a remote or isolated location. The basic reproduction number of a disease is used to measure how easily the disease spreads through contact with infected individuals. Negative room pressure is a technique in health care facilities based on aerobiological designs. ==See also==