Spillover diseases are emerging faster than ever, thanks to humans


The rise of epidemics

Historical accounts offer insight into past pandemics. The Mesopotamian cuneiform tablets, the oldest written in the world, describe the plague and plague that raged in 2000 BC. Arbøll, Assyrian historian from the University of Oxford. Heavenly conjunctions involving the planet Mars, which was linked to the Assyrian god of death, could portend an epidemic.

Cuneiform texts describe how revered healers diagnose patients. Male exorcists or doctors combined the physical examination with environmental observations, which could range from the creaking of a house door to the animals that appeared. The way these animals moved was indicative of their impact: from the right, auspicious, from the left, not good, Troels says.

Healers would then consult written “omens” to concoct and administer herbal remedies, which they applied as poultices or poured into the appropriate opening. They chanted incantations and prayers to appease the deities and ritually dispel symptoms by melting a figurine of the patient in a fire or throwing it into a river.

The warnings for rabid dogs are the only mention of zoonotic diseases in the tablets. But other ancient evidence exists. Smallpox is described in early Indian, Chinese and Egyptian writings. When archaeologists discovered the mummy of the ancient Egyptian pharaoh Ramses V in 1898, they found his skin covered with scars. He and two other mummies have revealed that smallpox has been around for at least 3,000 years. The researchers note that it may have jumped out of a rodent pox virus; rodents are also a reservoir for the closely related cowpox and camelpox.

One of the earliest documented plagues in history – the virulent plague of Athens – ravaged ancient Greece from 430 to 425 BC. Then they began to travel, unwittingly spreading germs across the ancient world in a process Morens calls “pathogenic pollution.”

The plague of Athens is believed to have arrived by sea, devastating a city ripe for contagion. At the time, Athens was at war with neighboring Sparta and the city was teeming with refugees.

Historian Thucydides lived in Athens during the plague and detailed the symptoms vividly. People’s heads were burning with fever, their mouths bled, their eyes turned red, they coughed, vomited, suffered from dysentery and developed unquenchable thirst. Their reddened skin burst into ulcers. Most died within a week. Suffering “seemed almost beyond the capacity of human nature to endure,” writes Thucydides in the History of the Peloponnesian War.

The scavenging animals avoided the unburied dead. Shrouded in a specter of death, the city sank into “an unprecedented anarchy …

This mysterious plague has yet to be identified, although experts suggest it could be anthrax, smallpox, typhus, or one of two dozen other infectious candidates. Either way, the plague killed tens of thousands of people and a weakened Athens fell to Sparta in 404 BC.

Change the story with waves of sickness

Over the following centuries, devastating waves of bubonic plague, measles and smallpox wiped out scores of people on three continents.

“It shows just how interconnected the world was 2,000 years ago,” explains Lucie Laumonier, historian at Concordia University in Montreal. The Silk Road and trade ships connected Europe with North Africa and Asia, creating great opportunities for microbes, with each epidemic changing human history in its own way.

A pandemic may have hastened the demise of the Han Empire in 160 AD. Just five years later, the returning Roman armies from West Asia imported an unknown disease that caused the plague of Antonius. He killed Emperor Marcus Aurelius along with five million Romans and devastated the empire, affecting both the army and agriculture and emptying state coffers.

The Justinian plague struck Constantinople, now Istanbul, during the 6th century, the first of three pandemics of bubonic and pneumonic plague. They are among mankind’s deadliest biological events, according to Georgetown’s Timothy Newfield.

Historian Procopius, who carefully recounted the reign of Emperor Justinian, wrote that “there was a plague, by which the whole human race was nearly wiped out.” He claimed he was from Egypt, which shipped wheat to Constantinople. It is doable: grain shipments at the time could have transported plague rodents and fleas.

Mongolian armies may have been responsible for the next bubonic plague pandemic by unintentionally bringing flea infested rats from Central Asia to Ukraine in 1346 during the siege of Kaffa. Some historians have suggested that the Mongols used biological warfare and catapulted diseased corpses over city walls to infect those inside. However, the evidence is limited and critics have since questioned this idea.

Either way, the survivors fled, sailing from the Black Sea to Genoa and Messina and taking the Black Death with them. Within three years, the disease had spread to England, Germany and Russia.

In 1348, the Italian poet Giovanni Boccaccio described the bubonic plague as a disease which “would rush on its victims with the speed of a fire passing through dry or oily substances … Swelling, either on the groin or under the armpits … the size of an ordinary apple, others the size of an egg. These buboes turned black and purple, oozing blood and pus. The victims were shaken with fever, pain and digestive disturbances.

In an attempt to cure them, doctors often used induced bleeding or vomiting. Most of those infected died quickly. “The magnitude of the mortality was unlike anything we can even imagine,” Newfield explains.

Superstition reigned. Some people believed that planetary movements, bad air or poisoned water were the cause of this deadly plague. Many thought it was a punishment from God. Other people blamed the strangers. Various minority groups have been driven out, tortured or killed. “The desire for a scapegoat is very, very old,” Newfield says.

Meanwhile, rats and fleas thrived in cities without regular garbage collection. They dug into rugs made from wetland rushes and munched on leftovers that were thrown at pet cats and dogs. Their role in the pandemic has gone unnoticed, as have the lice which may also have been carriers.

Back in Asia, the plague killed some 16 million people. As pandemics limit travel and trade, this scourge caused the Mongols to lose control of Persia and China, ultimately covering up their empire.

The ancient roots of prevention

The fear of contagion during this second plague epidemic triggered countermeasures that are still used today.

In 1377, in the Venetian port of Ragusa (now Dubrovnik, Croatia), the authorities set up a place outside the city to treat sick residents of the city. They also isolated all ships and land caravans for 30 days before allowing travelers to enter the city. This then extended to 40 days – or quarantine in Italian. These measures created the cornerstone of medieval preventive social distancing.

Yet the plague ebbed and recurred for the next 400 years. A fierce epidemic of 1664 in London is famous for its “dead carts” slamming along cobblestone streets with drivers shouting “Bring out your dead”, immortalized by Monty Python. The last of three bubonic plague pandemics began in China’s Yunan Province around 1855 and lasted until 1960.

It was during this episode that the Swiss scientist Alexandre Yersin discovered the bacterial cause in 1894. Four years later, Jean-Paul Simond traced the transmission of rodents to fleas to humans. When the bubonic plague crossed the Pacific and reached San Francisco in 1900, authorities rejected the accumulated science, instead quarantining Asian immigrants.

In 1897, scientists developed a preliminary vaccine; a better version appeared in 1931, and antibiotic treatment proved effective in 1947. With these tools in hand, plague in humans can be controlled and large epidemics are much less likely. However, bacteria still circulate in nature. The plague made headlines last August after it was detected among chipmunks in Lake Tahoe, California, forcing some tourist destinations to close.


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