Pandemics through the ages

Historians believe that humans have been pounded by flu pandemics at various times for at least four hundred years. But a flu pandemic is a rare event, taking place only two or three times a century.

On the other hand, every year we experience a seasonal flu epidemic. There's no question it's contagious, passing from person to person. But it certainly doesn't sweep across the planet the way a pandemic does.

In Canada, ordinary seasonal flu is directly responsible for the deaths of between 500 and 1,500 people every year. It also kills many more Canadians who develop complications like pneumonia. Most of these victims are very old or young, or have already weakened immune systems.

A pandemic, on the other hand, is fast and furious. It can sicken or kill normally healthy, working-age adults. Those who get better will take a long time to recover. Often, a second wave of sickness comes a few months after the first, claiming even more victims. A pandemic can have a serious impact on the economy and on social supports like the health care system.

Prominent pandemics of the 1900s

Last century, the world suffered through three separate pandemics:

• The Spanish flu in 1918-1919 was probably the worst pandemic on record. One or two out of every five people in the world got sick. The Spanish flu killed between 20 and 40 million people around the globe. For unknown reasons, most victims of this virus were in the prime of their lives.
• By the time the Asian flu first appeared in 1957-1958, modern medicine had advanced considerably. Scientists were able to identify the virus and, to a limited degree, produce a vaccine. Schools played a role in the quick spread of this disease. Most of the dead, though, were elderly.
• The Hong Kong flu hit in 1968-1969. This virus strain was most likely created when an animal became infected with a human flu and an avian flu at the same time. This was a relatively mild pandemic, killing a mere four million instead of 40 million.

Since 1969, the world's pandemic panic button has not been silent. We've had several scares. The swine flu in 1976 was at first thought to be similar to the powerful Spanish flu, raising alarms. The Russian flu in 1977 moved dangerously quickly through schoolchildren, but it was later found that many adults had already developed immunity.

Today, the potential of avian flu to spark a pandemic continues to be a concern. Many experts are worried that modern air travel will allow a pandemic flu virus to literally fly around the world fast.