When someone is known to be ill with a contagious disease, they are placed in isolation and receive special care, with precautions taken to protect uninfected people from exposure to the disease.
When someone has been exposed to a contagious disease and it is not yet known if they have caught it, they may be quarantined or separated from others who have not been exposed to the disease.
However, both quarantine and isolation may be conducted on a voluntary basis or compelled on a mandatory basis through legal authority. A state's authority to compel isolation and quarantine within its borders is derived from its inherent "police power" -- the authority of a state government to enact laws and promote regulations to safeguard the health, safety, and welfare of its citizens. States and local jurisdictions have primary responsibility for isolation and quarantine within their borders. The federal government has primary responsibility for preventing the introduction of communicable diseases from foreign countries into the United States.
Controlling the Spread of Contagious Diseases: Quarantine and Isolation
Contagious diseases that pose a health risk to people have always existed. While the spread of many of these diseases has been controlled through vaccination and other public health efforts, terrorist acts worldwide have raised concerns about the possibility of a biological attack. That makes it important for people to understand what can and would be done to protect the public from the spread of dangerous contagious diseases. The Centers for Disease Control and Prevention (CDC) is the U.S. government agency responsible for identifying, tracking and controlling the spread of disease. With the help of the CDC, state and local health departments have created emergency preparedness and response plans. In addition to early detection, rapid diagnosis and treatment with antibiotics or antivirals, these plans use two main traditional strategies?quarantine and isolation?to contain the spread of illness. These are common health care practices to control the spread of a contagious disease by limiting people's exposure to it.
Red Cross
http://www.redcross.org/preparedness/cdc_english/printpage.asp?ref=http://www.redcross.org/preparedness/cdc_english/IsoQuar.asp
Community Containment Measures, Including Non-Hospital Isolation and Quarantine
Guidelines for Evaluating Homes and Facilities for Isolation and Quarantine
Centers for Disease Control and Prevention (CDC)
http://www.cdc.gov/ncidod/sars/guidance/D/pdf/app3.pdf
Shelter In Place (SIP) Outreach
Many links to websites, preparedness guides, posters, etc.
LEPC Information Exchange
http://www.lepcinfoexchange.com/sipexamples.html