Known as:

Black death - coined 1832 by a German doctor who used it as the title of his essay on the outbreak of disease in Europe in 1348, Der schwarze Tod. It was also used in a history of England written by Elizabeth Cartwright in 1823 for unknown reasons. The connotation of "black" is "terrible" or "dreadful" according to David Herlihy, the author of the 1997 book "The Black Death and the Transformation of the West". Bubonic plague - the most common form of plague denoted by painful swollen lymph nodes, or buboes. Yersinia pestis infection - a bacterium carried by fleas names for the Swiss microbiologist who isolated it, Alexandre Yersin of the Pasteur Institute. Pasteurella pestis - original name of the bacterium named for the Pasteur Institute in Paris that Yersin worked for at the time. Plague is designated as a rare disease by the U.S. National Institutes of Health (NIH), meaning it affects less than 200,000 people a year in the United States. It is endemic to the Asian subcontinent and parts of Europe.

Where and when:

1348: The medieval Europe outbreak we learn about in school, recurred through the 15th century, by 1420 the population was one third it was before the epidemic. Some archaelogical evidence points to the epidemic starting earlier in the former Soviet Union ten years previous. Evidence suggests this was bubonic plague, but it seemed to be passed from person to person which suggests it was the more severe pneumonic form (lung infection). Also there was no large volume of rat deaths reported which is a necessary step for human infection, see below for details. 1894: China, where Yersin isolated the bacterium. It wasn't contained in Hong Kong and the plague spread from port to port, water-borne. 1896: Bombay, India - from here spread to ports in Portugal, Scotland, Australia, United States. Prompted the development of public health infrastructure in New York. 1901: San Francisco, United States - Chinatown infection from Asian ships probably carrying rats and infected fleas from overseas. 1996: India - Plague is now easily treatable with common antibiotics and appropriate hospital care. Only infectious to other humans if pneumonic.

Types:
	Bubonic - most common, the form most people think of. Named for the swollen lymph nodes. Pneumonic - more lethal form, bacteria found in the sputum and can spread from human to human. Septicemic - most lethal, bacteria infects the blood in such large numbers that the person dies in 24-36 hours.

How:

Yersinia pestis survives indefinitely in wold rodent populations including prairie dogs, squirrels, marmots, etc. Rats who come into contact with humans and are infected have been pointed out as the source of plague outbreaks. Fleas bite the infected rodents and become infected. When the rodents die, they need a new host and if necessary will jump to humans. This is how plague became water-borne, there were limited amounts of rats on the ships and the fleas moved to humans. Proper hygiene and animal control can prevent most cases of plague. In 2007 a dead squirrel in Denver, Colorado was found to be infected with plague. Once fleas infest humans they bite them to feed on their blood. This infects the person with the bacteria. It incubates for 2-8 days and then the person will have a soaring fever, reaching up to 105 degrees farhenheit, may have convulsions, vomiting, be sensitive to light, and have agonizing limb pain. The fever is followed by painful swelling of the lymph glands, usually in the groin, but also the armpits and neck. These are the namesake buboes. If left alone they will burst and the person will develop petechiae, small blood spots, on their skin. A person who survives and does not succumb to exhaustion, heart failure, or internal hemorrhage will begin to convalesce in 8-10 days. The bubonic form can become another form by disseminating to the lungs or bloodstream, like most infections. This is the current speculation for what we know as the Black Death. Many victims spit up blood prior to death and those who cared for them became infected as well.

Treatment:
	Infected individuals - Hospital care for symptoms and antibiotic treatment to clear the infection. Important in first 24 hours of pneumonic plague! Contacted individuals - Antiobiotic treatment to prevent infection and the wearing of surgical masks. There is no current inoculation method or vaccine.