7th Grade Research 2014

Between 1347 and 1351 a great epidemic known as the Black Death ravaged Europe. This pandemic took a proportionately greater toll of life than any other known epidemic or war up to that time. The Black Death is widely believed to have been the result of plague that was caused by infection with the bacterium Yersinia pestis. Most scientists think that this bacterium was passed from infected rodents to humans through the bite of fleas.

Plague is an infectious fever that takes three forms in humans: bubonic; pneumonic, and septicemic. The bubonic type is the mildest, accounting today for virtually no deaths and in the past killing about half of its victims. It is named for one of the disease’s characteristics, the formation of buboes, or inflamed lymph glands. Pneumonic plague attacks the lungs and is often fatal in three or four days without treatment. In septicemic plague, bacteria overwhelm the bloodstream and often cause death within 24 hours, before other symptoms have a chance to develop. It is believed that the Black Death was a combination of bubonic and pneumonic plague. The pandemic was called the Black Death because of the black spots that appeared on the skin of many victims.

(1749–1823) . For centuries smallpox was a scourge. The dread disease killed or left weakness and hideous scars. When late in the 18th century Edward Jenner, a young physician, startled the medical profession by claiming that people who had had cowpox would not get smallpox, his theory was scorned. After many years, however, doctors began using Jenner’s method, based upon his theory, of preventing smallpox. He called the method vaccination. By 1979 the disease was declared eradicated (see vaccines).

The death toll from a yellow fever epidemic in Philadelphia hits 100 on this day in 1793. By the time it ended, 5,000 people were dead. Yellow fever, or American plague as it was known at the time, is a viral disease that begins with fever and muscle pain. Next, victims often become jaundiced (hence, the term "yellow" fever), as their liver and kidneys cease to function normally. Some of the afflicted then suffer even worse symptoms. Famous early American Cotton Mather described it as "turning yellow then vomiting and bleeding every way." Internal bleeding in the digestive tract causes bloody vomit. Many victims become delirious before dying. The virus, like malaria, is carried and transferred by mosquitoes. The first yellow fever outbreaks in the United States occurred in late 1690s. Nearly 100 years later, in the late summer of 1793, refugees from a yellow fever epidemic in the Caribbean fled to Philadelphia. Within weeks, people throughout the city were experiencing symptoms. By the middle of October, 100 people were dying from the virus every day. Caring for the victims so strained public services that the local city government collapsed. Philadelphia was also the seat of the United States government at the time, but federal authorities simply evacuated the city in face of the raging epidemic. Eventually, a cold front eliminated Philadelphia's mosquito population and the death toll fell to 20 per day by October 26. Today, a vaccine prevents yellow fever in much of the world, though 20,000 people still die every year from the disease.

heart failure, pneumonia, osteomyelitis,