It’s so easy to travel nowadays, isn’t it? It used to be that travelling to faraway countries took weeks or even months on the road or at sea.

Now thanks to air travel, you can be in any city you want in less than a day. And where people go, viruses follow.

All it takes for a virus to spread is a single sneeze or cough.

During prehistoric times, humans were mostly hunters-gatherers who never stayed in one spot for long.

Whatever settlements they had were small and they tended to move around in search of new hunting grounds.

But when humans started to create settlements to farm, they lived close to animals, which allowed bacteria and viruses to spread from animals to humans.

Epidemics and pandemics vary in terms of transmission methods and lethality.

After the 2010 Haiti earthquake, overcrowded refugee camps were struck by an epidemic of cholera, a waterborne bacterium.

Epidemics are mostly caused by viruses like measles, influenza and HIV.

An epidemic is different from a pandemic in terms of scale; a pandemic is on a global scale.

Human history has seen many pandemics strike across the world. Archaeologists have dug up bodies with scars on the tissue and bone. Preserved DNA shows evidence of death due to pandemics.

Bacteria that spread tuberculosis have been found in ancient mummies by Egyptologists.

Researchers also dig up bodies of victims with traces of plague bacteria present from time to time.

The plague first started in China around 1340 and travelled westward on the Silk Road to reach the Mediterranean in 1347.

By 1400, 34 million Europeans had been killed by the Black Death. Historically though, flu remains the greatest pandemic killer. Seasonal flus are common in the West every autumn and winter.

Due to long-time exposure, flu infections are mild and will be gone within a few days or weeks.

But every few decades, the flu virus mutates drastically. When wild flu viruses with different hosts meet, they can exchange genes in a process called the antigenic shift.

This has occurred many times previously with the first recorded pandemic breaking out in 1580.

The worst pandemic in terms of its death toll is the Great Flu Pandemic of 1918, better known as the Spanish Flu.

500 million people were infected throughout the world and between 50 to 100 million people lost their lives.

Back then, international travel was somewhat limited, unlike now. Air travel today facilitates the transportation of viruses across the globe faster than any virus could spread in 1918.

When SARS first broke out in 2013, a single hotel guest in Hong Kong infected with Severe Acute Respiratory Syndrome spread the illness to 16 other guests within 24 hours.

These other infected guests then travelled to other countries, taking the virus with them.

As soon as it became clear what was going on, international flights were grounded and the SARS outbreak was contained within 29 countries, though more than 700 people sadly lost their lives.

SARS left Hong Kong scarred, with the economic consequences costing the city billions. It certainly didn’t help that conspiracy theories and fake news made matters more complicated.

Pandemics can be as deadly as natural disasters and conflicts. Thankfully, technology and science have progressed enough to enable people to detect pandemics quickly and plan accordingly to contain them before they spread beyond control.

Hopefully, with fears of a new pandemic due to the Wuhan coronavirus, science will once again prove to benefit humanity once more.