Meningitis is a relatively rare infection that affects the delicate membranes -- called meninges (men-in'-jeez) -- that cover the brain and spinal cord. Bacterial meningitis can be deadly and contagious among people in close contact. Viral meningitis tends to be less severe and most people recover completely without specific therapy. Fungal meningitis is a rare form of meningitis and generally occurs only in people with weakened immune systems.
The Black Death is thought to have originated in the arid plains of Central Asia, where it then travelled along the Silk Road, reaching Crimea by 1343. From there, it was most likely carried by Oriental rat fleas living on the black rats that were regular passengers on merchant ships.
The Black Death was an epidemic outbreak of bubonic plague in Europe around 1348 that killed between one-third and two-thirds of the population in less than five years. The epidemic spanned from China to England to North Africa, transmitted along the Silk Road and other trade routes. Worldwide, the plague may have killed one-quarter of all people. Repeated outbreaks continued in Europe into the 18th century. Some historians believe the drastic reduction in population hurried the end of feudalism by raising the value of labor and the power of workers, as seen in incidents like the 1381 Peasants Revolt in England.