Plagues were different from other infectious diseases. A plague was an epidemic of a new lethal disease to which nobody had any immunity. The rate of transmission was rapid enough that people who did not have symptoms yet carried it to others, but in a classic plague, they grew sick fairly quickly and died within days.
Thucydides described the Plague of Athens in 430 BC, a lethal outbreak that killed about 25% of the city’s population during two waves. Scientists are still not sure what the Plague of Athens was, in modern medical terms. Pandemic diseases are often zoonotic, that is, they jump from an animal host to humans who are not able to fight it off. There is not enough forensic medical evidence for the Athenian plague to identify an animal host, though at the time they say that it came from Ethiopia. The plague had a powerful political effect since Athens was fighting against Sparta and became fatally weakened after losing so many people.
Rome experienced a plague around the year 164, and again as the Empire weakened. “Galen’s Plague,” named for the Roman doctor who observed (but fled) it, may have been smallpox. When the Emperor Marcus Aurelius died, Roman power weakened. Another plague came through in 180; it was similar to the Athenian plague. Roman power had effectively ended in Italy and the West when the Plague of Justinian struck in 552. Justinian was the Eastern Roman Emperor in Constantinople; his efforts to regain the older limits of Roman power came to an end with the plague.
Justinian’s Plague is the first one for which we have more general, closer to worldwide, records. We know that it touched most of the known world, devastating population in China (perhaps its point of origin), India, Iran, Egypt, and Europe, all the way to Denmark and Ireland. It returned in at least five waves, until about 715. During this time, there were some significant conquests that may have been aided by plague losses by defenders: the Anglo-Saxons invaded Britain, perhaps taking advantage of sick Britons and Welsh, and the Arabs invaded the Byzantine cities of Damascus, Jerusalem and Alexandria.
But we don’t know what it was. It may have been the same Bubonic Plague that struck in 1347, or it may not. There isn’t sufficient evidence, because we can’t identify particular graves and bones for that plague alone.
What was Plague like, generally? Thucydides described a violent disease that nearly always killed its victims (he himself survived). It began suddenly, with violent pain and high fever. Within hours, victims broke out in sores. They coughed and retched; they had diarrhea and bled. They had spasms of pain or seizure. In some plagues, skin died, becoming black. The Plague of Athens took up to a week to kill someone, while some later plagues, including the Black Death of 1347, killed in as little as 8 hours.
Plague was simply the most frightening thing in the world. It’s no accident that Plague is one of the Four Horsemen of the Apocalypse in Revelation. Diseases that rise to the label of Plague attack nearly all body systems at once. They mutate even as they spread, becoming airborne and sometimes defying logic as to how they are transmitted. The amazing thing is that plagues never kill everyone, although there appears to be no reason why they shouldn’t. When we contemplate the horrors of a 60% death rate, which is about the maximum ever suffered in a plague, we must remember that this means 2 out of 5 people never got sick, or were mildly sick and recovered. Their natural resistance to the disease is what eventually ends the plague, since after it returns several times, a majority of survivors have immunity.
Next we’ll talk about the exact plague that struck in 1347. It all started with woodchucks.