Plague

Plague is a disease found mainly in rats, ground squirrels, and prairie dogs caused by a Gram-negative bacillus. It is normally transmitted by a fleabite except in its respiratory form when it passes from human to human by respiratory droplets. In 541 A.D. it killed 50 to 60% of the population of North Africa, Europe, and central and southern Asia. The Black Death, which began in 1346 and lasted 130 years, killed 20 to 30 million people in Europe (about 1/3 of the population). The Tatars used plague as a weapon in 1345 against Genoese settlements in the Crimea, and the Japanese dropped plague-infected fleas over a town in China, killing 392 people during WWII. They planned to spread the disease in California in 1945 but surrendered before completing the mission.