The spread of an infectious disease within a given population is known as an epidemic. It becomes a pandemic when the infectious disease spreads across various countries. In the domain of infectious diseases, a pandemic is by far, the worst-case scenario.

Pandemics have not only changed human history through human-to-human transmissions but also have affected the animal kingdom, which reduced food supply, and led to famine and starvation. Through historical records, it is proven that the more civilized humans became, building cities and forging trade routes to connect with other cities, and waging wars with them, the more likely pandemics became. In today’s world, our movements and travels across borders happens daily – for business and more so for leisure. The technologically advanced world that we live now, has caused the widespread of modern-day pandemics to be harder to control.

Here are some epidemics and pandemics in the 20th century that changed world history.

1918: Spanish Flu
The 1918 flu was first observed in Europe, the United States and parts of Asia before swiftly spreading around the world. The avian-borne flu was first detected in Madrid, hence named Spanish flu. It resulted in 50 million deaths worldwide. At the time, there were no effective drugs or vaccines to treat this killer flu. But the spread stopped in 1919 when most of the infected had either developed immunities or died.

1957: Asian flu
Starting in Hong Kong and spreading throughout China and then into the United States,
The Asian flu which started in Hong Kong became widespread in England where, over six months, 14,000 people died. A second wave followed in early 1958, causing an estimated 1.1 million deaths globally. A vaccine was later developed, which effectively contained further spread of the pandemic.