Mass Psychosis - How an Entire Population Becomes Mentally Ill, page-8

Some plagues and pandemics thru history -

-When soldiers returned to the Roman Empire from campaigning, they brought back more than the spoils of victory. The Antonine Plague, which may have been smallpox, laid waste to the army and may have killed over 5 million people in the Roman empire,

-Around 430 B.C., not long after a war between Athens and Sparta began, an epidemic ravaged the people of Athens and lasted for five years. Some estimates put the death toll as high as 100,000 people.

-The Byzantine Empire was ravaged by the bubonic plague, which marked the start of its decline. The plague reoccurred periodically afterward. Some estimates suggest that up to 10% of the world's population died.

-Named after St. Cyprian, a bishop of Carthage (a city in Tunisia) who described the epidemic as signaling the end of the world, the Plague of Cyprian is estimated to have killed 5,000 people a day in Rome alone.

-The Black Death traveled from Asia to Europe, leaving devastation in its wake. Over 50 million victims.

- The infection that caused the cocoliztli epidemic was a form of viral hemorrhagic fever that killed 15 million inhabitants of Mexico and Central America. Among a population already weakened by extreme drought, the disease proved to be utterly catastrophic. "Cocoliztli" is the Aztec word for "pest."

-The American Plagues are a cluster of Eurasian diseases brought to the Americas by European explorers. These illnesses, including smallpox, contributed to the collapse of the Inca and Aztec civilizations. Some estimates suggest that 90% of the indigenous population in the Western Hemisphere was killed off.

-The Black Death's last major outbreak in Great Britain caused a mass exodus from London, led by King Charles II. By the time the plague ended, about 100,000 people, including 15% of the population of London, had died.

- Great Plague of Marseille started when a ship called Grand-Saint-Antoine docked in Marseille, France. Plague spread quickly, and over the next three years, as many as 100,000 people may have died in Marseille and surrounding areas. It's estimated that up to 30% of the population of Marseille may have perished.

And on and on it goes.

So lucky we have modern health systems and Vaccines.
https://www.livescience.com/worst-epidemics-and-pandemics-in-history.html