Plagues and Stats

                                  Plagues and Stats

The plague was caused by Yersinia pestis (or Y. pestis), a bacillus carried by fleas that live primarily on rats and other rodents that were common in medieval dwellings. Y. pestis causes three varieties of plague: bubonic plague, caused by bites from infected fleas, in which the bacteria moves to lymph nodes and quickly multiplies, forming growths, or buboes; pneumonic plague, a lung infection that causes its victim to cough blood and spread the bacteria from person to person; and septicemic plague, a blood infection that is almost always fatal.
A plague epidemic swept through Europe from 1348 through 1351, killing an estimated 25–60% of Europeans. Some estimates are as high as 2/3 of the population. Current estimates are that between 75 and 200 million people died from the plague. The pneumonic plague killed 90-95% of its victims. The septicemic plague killed nearly 100% of the people it infected and still has no cure to this day. Although the period known as the Black Death ended in 1351, the plague continued to return to Europe, with epidemics every few years through the end of the 15th century. A third plague pandemic began in China and India in the 1890s and eventually reached the United States. The Black Death was the second plague pandemic of the Middle Ages. Justinian’s Plague in the 6th century was deadly and widespread, but did not create the same devastation as the second pandemic.

In 2002 and 2003, SARS infected more than 8,000 people worldwide, and more than 700 of them ended up dying.

The global mortality rate from the 1918/1919 pandemic is not known, but an estimated 10%, (and up to 20%), of those who were infected died. With about a third of the world population infected, this case-fatality ratio means 3% to 6% of the entire global population died.


The Chinese bird flu, H7N9, is said to have a human mortality rate of 30 to 39 percent.