History is full of catastrophes, and a plague is without doubt one of the deadliest. Modern medicine provides relief from some of them these days, but in past centuries humans have been at the mercy of all kinds of bacteria, viruses and other icky stuff.

Hindsight is always 20/20. Here is a list of famous human pandemics, and how the diseases responsible would be handled today.

The plague of Athens
430-427 BC

Back Then: It was the early years of the Peloponnesian war, and Greek city-states Athens and Sparta were at each other’s throats. Athens had withdrawn behind its city walls to allow its navy to attack the Spartan land troops, so the city was densely populated with Athenians moving in from all over the countryside. Suddenly, a deadly and highly contagious disease entered the city through its port, turning the crowded city into a plague breeding ground. The contagion spread at an incredible rate, causing rampant fever, exhaustive vomiting and diarrhea, and a general delirium, often killing the infected after only a few days. The details of the illness were recorded vaguely, but whatever it was, it killed a quarter of the Athenian troops and a third of the city’s population, including its celebrated leader, Pericles. History’s first recorded plague contributed to Athens losing the war and its domination of the region.

Nowadays: Though the exact cause of the epidemic still isn’t known, most theories point to epidemic typhus caused by the bacteria Rickettsia prowazekii. A preventative vaccination was created in 1930, and this, along with fluid replacement and antibiotics like tetracycline, has since brought the disease’s mortality rate close to zero.

The Antonine Plague
165-180 AD

Back Then: Roman troops returning from the Near East in 165 AD brought back with them war spoils, prisoners -- and a plague that caused up to 2,000 deaths a day in ancient Rome. The Antonine Plague was named after ruling emperor Marcus Aurelius Antoninus, and was described by Greek physician Galen as a long, cruel illness that involved fever, diarrhea, and inflammation of the throat, as well as a breakout of pustules on the skin. Besides decimating the Romans, the plague was a major contributor to the weakening of the entire Roman empire, as the thinning Roman army began to lose ground in the East and the North. The plague killed Marcus Aurelius himself in 180 AD, depriving Rome of its last great leader. It broke out again almost 100 years later, when the deacon Pontius wrote accounts of rotting human carcasses lying in the streets, and a terrified populace shunning the infected, leaving them to die.

Nowadays: Though, again, historical descriptions of the disease are vague, historians tend to believe it was smallpox. If this is the case, modern medicine offers a vaccine made from the vaccinia virus, as well as the antiviral drug Cidofovir and its derivatives, which significantly slow the virus’s reproduction. The mortality rate has since been lowered dramatically.

The Plague of Justinian
541-542 AD

Back Then: The Byzantine Empire, which more or less comprised the Eastern half of the Roman Empire, needed to import much of its grain from Egypt in order to feed its population. In 541 AD, it accidentally imported a plague that devastated most of the empire, including its capital of Constantinople. Historians of the day did not keep detailed records of the plague’s effects on the people, but descriptions exist of bodies being stacked in the open because they couldn’t be buried fast enough, and the surge of inheritance suits created confusion among public administrators. Byzantine historian Procopius recorded that at its height, the plague was killing 10,000 people each day in the city. Modern historians put the number closer to 5,000, but ultimately the plague killed around 40% of the city’s inhabitants. By the year 700, after subsequent outbreaks had ended, up to 60% of Europe’s population was dead.

Nowadays: Modern historians have pieced together enough evidence to reasonably assume the culprit was bubonic plague, a lymph node infection caused by fleas carrying the bacteria Yersinia pestis. Modern treatments include antibiotics such as streptomycin, tetracycline and chloramphenicol, and if treated in time, it can now be cured in 85% of cases.

The Black Death
1347-1351

Back Then: The Black Death was the most famous, and one of the deadliest, pandemics in human history, responsible for wiping out between 30% and 60% of Europe’s population during the Middle Ages, and lowering the world’s population by 75-200 million. Once arriving in western Europe via merchant ships, it spread rampantly from city to city creating widespread terror and panic. Victims broke out in large, oozing pustules, vomited profusely, coughed up blood, and contracted other conditions such as necrosis and gangrene. Four out of five victims died within eight days, and cities were quickly overtaken by piles of rotting corpses, vast cemeteries, shallow mass graves, and enormous funeral pyres. The plague returned several times over the next few hundred years, bringing social havoc and large-scale mortality, until subsiding in the 1700s.

Nowadays: The Black Death is mostly chalked up to the same bubonic plague that affected Constantinople 800 years earlier. Fleas on European rodents were carrying Yersinia pestis, which spread through flea bites. The bites would itch, causing the victim to scratch and rub the flea’s infected feces into the wound. This infection is still serious in underdeveloped parts of the world, but with modern antibiotics it is survivable in the vast majority of cases.

The Native American Smallpox Epidemic
Roughly 1500-1900

Back Then: By the time European settlers began to move across North America, large numbers of the native populations had already been killed by the advance of European diseases, which had preceded the settlers’ presence. But that didn’t stop settlers, who saw Indians as vermin, from adding germ warfare to their methods of wiping them out. Many deadly diseases were introduced either advertently or inadvertently among the Indians, effectively decimating their numbers as the natives had no previous exposure or resistance. The worst of them was smallpox. This disease was made especially notorious because of an incident during the French and Indian War in which British commanders at Fort Pitt (now Pittsburg) discussed supplying the Indians with smallpox-infected blankets in an attempt to reduce their numbers. Whether the plans were carried out is not confirmed, but it is known that Delaware Indians in the area soon began spreading smallpox rampantly. By the late 1800s, it and other diseases had wiped out up to 90% of all Indians, making the Indian depopulation one of history’s greatest human catastrophes.

Nowadays: With the advent of the smallpox vaccine and other antiviral drugs, a human case of smallpox has not been seen in over 30 years – the last documented case was that of an un-vaccinated cook in Somalia 1977. Since 1980, as declared by the World Health Organization, smallpox is the only disease to have been completely eradicated.

The First Six Cholera Pandemics
1816-1923

Back Then: Between 1816 and 1994, massive outbreaks of Cholera spread across the globe in seven pandemics. The first six were the most deadly, killing huge numbers of people in Asia, India, Europe, Russia, the Americas, the Middle East, Egypt and Africa. Untreated victims died within as little as 3 hours of the first symptoms, literally of fluid loss due to acute diarrhea, accompanied by vomiting, cramps and slowing blood pressure. In Chicago in 1854, Cholera killed 5% of the city’s population. One 1853 outbreak in London was only stopped when physician John Snow had the handle of the Broad Street water pump removed, proving the source of the outbreaks to be water contaminated by the feces of other cholera victims. Still, it took over 50 years for word to get out, and cholera continued to be a scourge of urban areas until the 1920s, when most countries had updated their public health systems.

Nowadays: Cholera, and its causal agent Vibrio cholera, still crops up in small, isolated outbreaks affecting underdeveloped areas where water systems and public hygiene are poor. However, most of the world has adapted their water systems to prevent contamination -- and in the event of an outbreak, continuous fluid replacement and antibiotics like tetracycline have lowered the disease’s mortality rate to below 1%.

The Spanish Flu Pandemic
1918-1920

Back Then: During the height of World War I, a shockingly virulent strain of Influenza-A swept the world, spreading quickly to regions as far apart as Asia, Australia, North America, Europe, the Pacific islands and even Arctic territories. Whereas most flu epidemics affect weaker populations, such as infants or the elderly, this one involved a mutation that allowed the virus to overtake the immune system and turn it against the victim’s body. This resulted in a much higher mortality rate among the otherwise young and healthy, whose immune systems were stronger, as well as a devastating toll on social productivity. Everyday life stopped, schools and shops closed, and even gravediggers were too sick to bury the dead. In some cases, mass graves were dug using steam shovels, and bodies were buried without coffins. The mass infection affected nearly one third of the world’s population, causing between 50 million and 100 million deaths – more than all the wars of the 20th century combined.

Nowadays: Modern medicines such as Tamiflu and Relenza have proven effective in subduing flu symptoms and preventing transmission, and diseases are much more quickly identified today than they were then. Hygiene, such as hand-washing, is also more directly linked to stopping transmission. Though Influenza still presents a public health concern (such as the recent swine flu epidemic), it is much less devastating than it has been in the past.