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.
It used to be thought that the Black Death originated in China, but new research shows that it began in the spring of 1346 in the steppe region, where a plague reservoir stretches from the north-western shores of the Caspian Sea into southern Russia.