There's a reason the term "plague" has become a catch-all description for something that devastates. The plague bacterium, Yersinia pestis, is arguably one of the deadliest diseases on the planet, having caused an estimated 200 million deaths over the course of recorded history [source: Perry]. Symptoms include fever and chills, swollen lymph nodes and muscle aches [source: Mayo Clinic].
Plague pandemics have swept through the inhabited world for centuries, and historians have divided the outbreaks into three pandemics. The Justinian Plague erupted in the Mediterranean from 541 AD to 700 AD. The infamous Black Death killed roughly 40 percent of Europe's population in the 14th century. And the third plague pandemic, which started in Asia in the mid-1850s, spread to every continent but Australia. Antibiotics tempered plague in the 1950s, but it still appears in isolated outbreaks; technically, the third plague pandemic is still underway [source: Perry].
The WHO documents 1,000 to 3,000 cases of plague every year [source: CDC]. And as people encroach on once-wild areas, they are increasingly likely to come into contact with plague-bearing animals and the fleas that transmit the disease through their bites.
Plague can be treated if caught early enough, but eradicating the disease would be impossible: With the ability to affect a variety of mammals, plague is a disease that can strike, cause great suffering, and then seemingly vanish into thin air.