1. Black Death (1347)
Death toll: ~200 Million
The Black Death was one of the worst pandemic in history. In 1347, one third of the human population of Europe died as the plague swept through. Also known as bubonic plague, the disease was caused by the bacterium Yersinia pestis and it can travel from person to person through the air or carried by infected fleas and rodents. As of today, there are still 1,000 to 3,000 cases of plague each year according to WHO (World Health Organization).
2. Smallpox (1520)
Death toll: ~55 Million
Smallpox is a severe and contagious disease caused by the Variola virus. It killed an estimated 400,000 Europeans each year in the 18th century and approximately 90% of Native Americans. It was spread mostly by breathing in the virus during close or face-to-face contact with a contaminated person. It also spreads through drops of saliva when the infected person sneezes, coughs, or speaks. In 1975, 3-year-old Rahima Banu of Bangladesh had become the last case of human infection by smallpox.
3. Spanish Flu (1918)
Death toll: ~50 Million
Spanish flu is an influenza outbreak of 1918-1919 which have killed more people than the World War 1. Affected individuals would develop a fever and short of breath. In 1918, the studies found that the major key to flattening the curve was actually the social distancing practice. And it likely remains valid a century later, in the recent battle against COVID-19.
4. Plague of Justinian (541)
Death toll: ~40 Million
The Plague of Justinian was one of the deadliest plagues in known history. The plague acquired its name at that time from the ruler of the Byzantine Empire, Justinian I. Similar to the Black Death, both plagues were known to have been spread by fleas and rodents. It is believed to be the very first significant appearance of the bubonic plague. Sufferers of the plague starts showing symptoms of swelling of the lymph nodes in the armpits and groins. This was then followed by fever, blood vomit and discoloration.
5. HIV/AIDS (1981)
Death toll: ~30 Million
HIV (Human Immunodeficiency Virus) is the virus that causes AIDS (Acquired Immune Deficiency Syndrome). It damages and weakens your immune systems and people’s defence systems against infections and cancers. HIV most commonly spreads through unprotected sexual activity with a person who has HIV or via drugs injection. It is carried in blood, vaginal fluids, anal mucus, breast milk, and cum (semen). In 2018, there were roughly 37.9 million people around the world with HIV/AIDS.