Lessons from SARS.

I t is the nature of epidemics to be unpredictable. People want answers to some important questions: How serious is severe acute respiratory syndrome (SARS)? Will SARS be contained in Toronto, or Singapore, or China? How far will it spread and how rapidly? What can the global community do to prevent and control future epidemics? Much has been learned from previous infectious disease epidemics and from the current SARS epidemic. In the absence of effective vaccines or drugs, infectious diseases that are spread by the respiratory route—whether the influenza epidemic of 1918 that killed 20 to 40 million people worldwide or measles, which spreads rapidly among children—must be taken very seriously. The key to controlling epidemics is to block the transmission of infection. If public health officials can identify people infected with SARS and isolate them for an appropriate time, the cycle of transmission can be broken. If it is not, there is a possibility that SARS will establish itself in communities, and we will have to cope with it for a long time. Voluntary isolation and quarantine are a great inconvenience for a lot of people, but they are currently our best tools to save lives. Because of the enormous economic and political impact of epidemics , it takes great courage in public health to declare to the world that a country has an epidemic. When the World Health Organization (WHO) recognized in March, after one of its top infectious disease specialists was infected by SARS in Hanoi and died, that there were similar cases in Hong Kong and rumors of more cases in China, it declared a Global Alert for the first time in WHO history. That gave every country in the world time to get prepared for a potential global epidemic. If public health really works well and a health problem is prevented, there is little evidence to show that something important was achieved. When public health officials don't act quickly enough, outbreaks become epidemics. However, when officials warn about a possible epidemic that then fails to spread, billions of dollars may be lost to national economies, as was the case in India with the outbreak of plague in 1994; and public health officials put their own jobs in jeopardy, as we in the United States learned after the swine flu outbreak of 1976. The wrong lesson to be taken from SARS would be to pass new …