Rabies, a virus which affects the central nervous system, is found in saliva, brain tissue, and cerebral spinal fluid of animals and/or humans infected by it. Following years of decline in the United States, the number of reported rabies cases in animals is rising dramatically. Today, with improved vaccines and prompt treatment, human death from rabies is rare: six people died from the disease in 1994 and four in 1995.

Louis Pasteur's memories of witnessing—at the age of nine—a mad wolf snapping at animals and humans in his home town, and the cauterization of one of the nine victim's wounds by a blacksmith's red-hot poker, played a significant role in his decision to investigate the deadly rabies virus. Rabies was not very common in the eighteenth century, however victims eventually died due to destruction of nerve cells in the brain, but not before going through...