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Pandemics are global outbreaks of serious diseases that exceed normal levels of mortality and infection. They have historically been the worst killers of humans, with smallpox, influenza, cholera, typhoid, and bubonic plague causing the largest pandemics. The Black Death and Spanish flu killed millions of people and changed the course of history. Governments fear a new pandemic caused by a mutation of bird flu.
A pandemic is a global outbreak of a serious disease that exceeds “normal” levels of mortality and infection levels for a typical disease. In this respect, the definition of a pandemic is partially subjective, but in most cases the difference between the normal background state and a pandemic state is surprisingly obvious. Throughout history, pandemics have been the worst killers of human beings, killing more people than all wars and accidents in modern history combined. Only in the last 90 years or so it seems that the historic pandemics are mostly under control, even though the HIV virus, which emerged in the 1980s, has killed millions of people and continues to be a serious problem to this day.
Historically, the largest pandemics have been caused by smallpox, influenza, cholera, typhoid, and the bubonic plague. The largest pandemic in history is often cited as the Black Death (thought to be the bubonic plague), which claimed 75 million lives and killed about a third of the population of Europe and China in the late 1340s. Recovery took more than a generation. Native Americans and Native Australians were fortunate that these populations were disconnected from those of Africa and Eurasia at the time. The Black Death was spread by infected rats.
Another massive pandemic, the Spanish flu, swept across the globe in 1918, just after World War I, killing 50-100 million people and rivaling the intensity of the Black Death. This flu was unusual in that it killed people in the prime of their lives rather than just old people or children. The deaths are thought to have been caused by cytokine storms, an overactive immune system response that leads to the death of the organism it is supposed to protect. In a cytokine storm, immune cells flood the body so quickly that they do even more damage than the flu itself.
When pandemics occur, they have dramatically changed the course of history and changed world events. Had the Black Death not occurred in Europe, economic and technological progress might have accelerated and Columbus might have reached the Americas even a hundred years earlier. Today, many governments fear a new pandemic caused by a mutation of bird flu, and hundreds of millions of doses of vaccine vaccines have been stockpiled.
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