Photo Credit CDC PHIL
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Although controversial, and often misunderstood, quarantines have a long and successful history of helping to curb the spread of disease transmission during epidemics.
With the emergence of SARS early in the last decade, the use of quarantines made headlines once again around the world, eliciting both praise and concern.
Just so we are all on the same page, here is how the CDC defines Quarantine and Isolation:
The CDC applies the term "quarantine" to more than just people. It also refers to any situation in which a building, conveyance, cargo, or animal might be thought to have been exposed to a dangerous contagious disease agent and is closed off or kept apart from others to prevent disease spread.
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.
The difference between quarantine and isolation can be summed up like this:
- Isolation applies to persons who are known to be ill with a contagious disease.
- Quarantine applies to those who have been exposed to a contagious disease but who may or may not become ill.
During the 2003 SARS epidemic, Isolation was used in the United States for patients who were ill, but since transmission of the virus was very limited here, quarantine was not recommended for those exposed (cite).
In other countries, where transmission risks were greater, quarantines were used – quite successfully – in order to contain the virus.
- Singapore was one of the first countries to mandate quarantines when more than 800 family members of SARS patients were ordered to stay in their homes.
- Hong Kong sealed part of the Amoy Gardens Apartment complex after scores of cases erupted there, and later moved all remaining residents to two holiday camps where they were quarantined.
- And Toronto, Canada closed schools and quarantined thousands in their bid to contain the virus (see The SARS Experience In Ontario, Canada).
The graph below shows two distinct phases of disease transmission in Canada, both apparently dampened by the implementation of quarantines.
While the aggressiveness of quarantine measures taken in Toronto have been criticized by some (see Severe acute respiratory syndrome: Did quarantine help?), many experts have stated that quarantining those exposed (usually in their own homes) helped to halt the epidemic.
A 2003 MMWR report from China’s CDC, called Efficiency of quarantine during an epidemic of severe acute respiratory syndrome--Beijing, China, 2003 found:
The use of quarantine, in combination with enhanced surveillance, isolation of SARS patients, and comprehensive use of PPE by health-care workers, appears to have been effective in controlling the recent epidemic of SARS in Beijing.
Limiting quarantine to persons who have contact with an actively ill SARS patient will likely improve the efficiency of quarantine and allow for better focus of resources in future outbreaks.
Disease transmission dynamics are different with different pathogens, so the lessons from SARS may not be applicable to the next pandemic.
All of which serves as prelude to an interesting look at the history of quarantine through the ages that appears today in the CDC’s EID Journal.
Historical Review
Lessons from the History of Quarantine, from Plague to Influenza A
Eugenia Tognotti
Abstract
In the new millennium, the centuries-old strategy of quarantine is becoming a powerful component of the public health response to emerging and reemerging infectious diseases. During the 2003 pandemic of severe acute respiratory syndrome, the use of quarantine, border controls, contact tracing, and surveillance proved effective in containing the global threat in just over 3 months. For centuries, these practices have been the cornerstone of organized responses to infectious disease outbreaks.
However, the use of quarantine and other measures for controlling epidemic diseases has always been controversial because such strategies raise political, ethical, and socioeconomic issues and require a careful balance between public interest and individual rights.
In a globalized world that is becoming ever more vulnerable to communicable diseases, a historical perspective can help clarify the use and implications of a still-valid public health strategy.
While unlikely ever to be popular (particularly among those caught up in one) – with novel emerging infectious diseases like SARS - particularly early in an outbreak, quarantines may be the only effective tool that public health officials have in their arsenal.
That said, the value of quarantines tends to diminish quickly as the number of cases, and geographic spread of a disease, increases.
