SARS is a coronavirus, like the common cold. However, its origin in southern China implies a zoonotic pathway, similar to influenza's. If SARS started as a water-borne bird virus, it might have been passed via faecal droppings to a chicken or a pig, or even directly to people. Three "superepidemics," known as pandemics, of influenza encircled the globe during the 20th century. History teaches us that the devastating 1918 influenza epidemic began with a modest level in the spring that faded away during the summer, only to explode and wreak global devastation the following fall and winter. The first was the 1918 Spanish Flu, a scourge that killed over 20 million people world-wide, including 500,000 in the U.S. The 1957 Asian Flu and the 1968 Hong Kong Flu killed 69,800 and 33,800 respectively in the U.S. Flu pandemics happen when the flu virus mutates, swaps genes with another organism inside an infected animal, or jumps from animals to humans. Travel restrictions are now in place at airports around the world after the World Health Organization (WHO) urged airports in SARS-affected cities to question passengers about their health before check-in and to discourage anyone who had a fever within the past 24 hours from flying. In addition to the airports serving Beijing, Shanghai, Guanghzou, Hong Kong, Singapore and Hanoi, restrictions have also been introduced in Toronto. This came after an elderly couple returning from Hong Kong brought the SARS disease to Canada, where there have been almost 300 reported cases. In addition to restrictions at airports and the WHO's travel warning, many countries have urged their citizens to reconsider traveling to Asia. This would not just adversely impact the region's tourist industry, but also other business activities (Anonymous, "Not only bad for your health," 2003). "This article summary is distributed under a Creative Commons Attribution 4.0 license (CC BY).