The Black Death - How it ravaged Europe | Dark History

The Black Death - How it ravaged Europe | Dark History
Plague is one of the deadliest diseases in human history, second only to smallpox. A bacterial infection found mainly in rodents and associated fleas, plague readily leaps to humans in close contact. Plague outbreaks are the most notorious epidemics in history, inciting fears of plague’s use as a biological weapon.

Today, plague cases still pop up sporadically around the world—including in the United States or China, where a suspected case was recently reported in the Inner Mongolia region. But the disease is no longer as deadly as it can be treated with antibiotics when available.

Here’s what you need to know about the plague, including how it spreads, the difference between bubonic and pneumonic plague, the most infamous plague pandemics in history, and why it’s not all that unusual to see modern cases of the disease.For hundreds of years, what caused plague outbreaks remained mysterious, and shrouded in superstitions. But keen observations and advances in microscopes eventually helped unveil the true culprit. In 1894, Alexandre Yersin discovered the bacterium responsible for causing plague: Yersinia pestis.

Y. pestis is an extraordinarily virulent, rod-shaped bacterium. Y. pestis disables the immune system of its host by injecting toxins into defense cells, such as macrophages, that are tasked with detecting bacterial infections. Once these cells are knocked out, the bacteria can multiply unhindered.

Many small mammals act as hosts to the bacteria, including rats, mice, chipmunks, prairie dogs, rabbits, and squirrels. During an enzootic cycle, Y. pestis can circulate at low rates within populations of rodents, mostly undetected because it doesn’t produce an outbreak. When the bacteria pass to other species, during an epizootic cycle, humans face a greater risk for becoming infected with plague bacteria.