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The headlines sound as if they were ripped from the Middle Ages, if the Middle Ages had had newspapers with headlines, that is. A fresh outbreak of bubonic plague, the Black Death, was reported in Madagascar last month. 84 cases were diagnosed, with the majority of those determined to be the more virulent form of the disease. Almost half of those infected died. The plague is not limited to less-developed areas, either.
The last epidemic in the USA was less than one hundred years ago. The Black Death certainly has staying power.
Where Does the Plague Come From?
Bubonic plague comes to us courtesy of a little bacteria named Yersinia pestis. As you may remember from your history lessons, this bacteria lives out its life cycle within the fleas that infest rodent populations throughout the world. Rats, squirrels, prairie dogs, mice, rabbits, even armadillos, all are host to fleas that carry the plague bacteria. The fleas, rodents, and bacteria have an enzootic relationship. The host animals have a steady infection rate without having an outbreak of the disease themselves.
The problem occurs when an epizootic cycle occurs. This is when the infection leaps to a different species and actually makes that species sick. This can happen either by other animals eating dead rodents that were plague hosts or by Yersinia pestis-carrying fleas biting other animals and transmitting the bacteria directly. Cats that contract the plague become very ill and can spread the disease to humans by coughing and sneezing. Dogs rarely become ill themselves, but they carry the infected fleas into homes.
What Does the Plague Do?
The symptoms depend on the form of plague. There quite a few kinds, but the most common ones diagnosed are bubonic plague, septicemic plague, and pneumonic plague.
People usually contract bubonic plague through the bites of infected fleas. There is a sudden, high fever along with headaches, chills, and body aches. It could be confused with a bad cold or the flu, but for the buboes. These are swollen, infected lymph nodes that develop under the arms and at the groin. They are very enlarged and extremely tender and painful.
Septicemic plague is what people are referring to when they call the plague "Black Death." It is also spread by flea bites, but can be contracted by handling dead animals that were infected. Septicemic plague can present as the first sign of infection or it can develop from untreated bubonic plague. Along with the fever, chills, and body aches of bubonic plague, septicemic plague also causes severe abdominal pain and shock. The disease microorganisms spread through the blood and those infected actually begin bleeding into their skin and organs. The skin turns black and dies.
Pneumonic plague is the most serious form, both for its virulence and its ease of transmission. It's contracted by inhaling droplets from other infected people or by leaving bubonic or septicemic plague untreated. There is a sudden onset of pneumonia that is accompanied by watery, bloody mucus and can lead to respiratory failure. This is the only form of plague that is spread directly from person to person.