Ruthless Microbes: The Greatest Epidemics in History

Plagues are perhaps the most relentless, egalitarian killers that humanity has ever feared; in fact. many of the worst not only killed, but also brutally sculpted the history of whole generations and regimes. Breaking through power structures, destroying entire populations and often even ushering in their own virulent successors, diseases on a mass scale have truly painted the violent history of our planet. Below are history’s most notorious diseases, in roughly increasing order of the chaos they caused:

Cholera: Stagnant water in Vietnam. Cholera grows best in contaminated, still water where whole colonies can form before flies transport the disease to human hosts. Occasionally, the contaminated water enters the drinking supply and infects hosts directly. Courtesy of

5. The Waterborne Killer: Cholera
Cholera had already plagued India’s contaminated sewage and water systems for millennia before cramped European cities of the Industrial Revolution allowed the disease to move. Spread through flies in contact with contaminated water, Vibrio cholera caused severe vomiting and diarrhea, which led to extreme dehydration. Oftentimes, given continued exposure, entire populations succumbed.

Better sanitation curbed the disease until 1961, when a new Indonesian strain (the Ogawa strain) spread rapidly through Bangladesh, India, the USSR, Iran, and Iraq. The same strain would later shatter Haiti after the 2010 earthquake, with 530,000 cases stemming from the crippled water infrastructure following the cataclysm. Although later controlled through chlorination of water, cholera limited metropolitan growth for centuries.

Yellow Fever: Vaccination for yellow fever in Togo. Mass vaccination in African countries has helped to stave off the disease, which often leads to liver failure and jaundice. Courtesy of Gavi Alliance.

4. The Malady of the Americas: Yellow Fever
As Europeans continued to colonize North America, epidemics from Africa took even deeper root in new, damp environments. Yellow fever, caused by a variant of the Flavivirus family and spread by the Aedes Aegypti mosquito, entered through the African slave trade. Victims developed muscle aches leading to liver failure with jaundice and bled profusely from the eyes and mouth.

Napoleon attempted to wrest control of French colonies from rebelling slaves — until over 80 percent of his troops sent to certain North American territories perished to the fever, allowing Toussaint L’Ouverture to liberate Haiti and persuade Napoleon to sell the Louisiana territory. Although controlled by removing stagnant mosquito breeding water and a mandated vaccine, yellow fever paved the road for regimes in the New World.

3. The Greater War: The Flu of 1918
1918 saw the end of grueling World War I. As civilians rejoiced, a new, biologically deadly war began to brew. As soldiers returned home, an H1N1 avian influenza virus entered fresh populations, spreading through bodily fluids.

Bizarrely targeting healthy young adults, the virus caused fever, nausea, and hemorrhagic diarrhea, followed by dark lesions upon the skin. The dark lesions eventually turned blue due to lack of oxygen as the lungs filled with a bloody froth.

European businesses suffered heavy losses following the wartime struggle. By the time the virus evolved into less virulent strains, the flu had took more casualties than all of World War I , with an estimated global death toll of 50 million.

Smallpox: The progression of smallpox over two weeks. The bumps erupt and form into pustules and raw, infectious skin. Courtesy of Viewzone Magazine.

2. The Terror of the Americas: Smallpox
Historians believe smallpox was first seen in the mummy of Ramses V and later in Indian records from 400 AD. The virus enters the respiratory tract and passes to the liver through blood before reaching skin cells but can also be passed through direct skin-to-skin contact. After two weeks, patients experience delirium and diarrhea before severe fever and a raised pink rash that turns into crusty, bumpy sores that hemorrhage. It yields a roughly 30 percent mortality rate.

Historically, smallpox was the Spanish conquest’s greatest ally in the 15th and 16th centuries, wiping out over 57 percent of the native population of Santa Domingo. It went on to crush half of the Cherokee Indian population by 1738. After WHO mass vaccination in 1967, scientists isolated the last case in Somalia in 1977.

Black Death: Families stack their dead outside their homes in Europe as the Black Death rages. Oftentimes, entire families would perish at once through contact with the same fleas. Courtesy of International World History Project.

1. The Archetypal Plague: The Black Death
Jump back to mid-14th century Europe. As small towns consolidate, a pandemic approaches from the east. Caused by the Yersinia pestis bacterium, the Black Death arrived via the Silk Road, carried fleas living on the black rats of merchant ships. Victims grew buboes (black swellings in the armpits, legs, and groin), which filled with blackened blood tinged by greenish scum.

The plague reduced the world population of roughly 450 million by 75 million before rats were identified as the vectors and were heavily exterminated. In England, people grew disillusioned with the Church and, with the scarcity of labor brought on by the Black Death, gained a deeper sense of self-worth, ultimately leading to the English Reformation.