"The Black Death" usually invokes mental images of tolling church bells, doctors with beak-shaped masks, necrotic tissue, grave diggers, and the Middle Ages - but that’s far from the whole story.
Meet Yersinia pestis: A Gram-negative, rod-shaped bacterium pictured here (in green) using scanning electron micrography on proventricular spines of a Xenopsylla cheopis flea (in purple). Yersinia pestis, which can infect most small mammals - cats, rats, dogs, and humans among them - is the cause of the bubonic, pneumonic, and septicemic plague. While we may now know that the Black Death was not caused by bad smells, as was once believed, Yersinia pestis has proven extraordinarily persistent - and resistant to eradication.
Because of the zoonotic relationship between Y. pestis, humans, fleas, and rats, the best we can do, to date, is contain outbreaks of the plague when they arise. Most recently, they’ve arisen in China, Peru, and the United States. While the spread of infection is quickly stopped and antibiotic treatment is effective, individual cases of the plague are often not isolated quickly enough, as was the case in China; early symptoms are general and include high fever, coughing, dizziness and vomiting, and resemble those of the flu. Don’t be fooled, though, infection with Y. pestis is still as deadly as ever: The index case in the Chinese outbreak died, and the septicemic plague (thankfully, the rarest form of the disease, caused when the bacterium enters the bloodstream directly), kills within 24 hours.
Image Credit: NIAID (National Institute of Allergy and Infectious Disease).