Rabies
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 byit. Following years of decline in the United States, the number of reportedrabies cases in animals is rising dramatically. Today, with improved vaccinesand prompt treatment, human death from rabies is rare: six people died fromthe 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 significantrole in his decision to investigate the deadly rabies virus. Rabies was not very common in the eighteenth century, however victims eventually died due todestruction of nerve cells in the brain, but not before going through severaldays of intense suffering which included throat spasms, fevers, delirium, and paralysis. Since inability to swallow water is a symptom of rabies, it wasalso called hydrophobia, meaning fear of water.
Rabies is usually spread by saliva from the bite of an animal infected with the virus. François Magendie, a French neurophysiologist, also showed that saliva from infected humans could transmit the fatal disease to dogs. (The only reported case of human-to-human transmission was through a corneal transplant from an infected donor.) Pasteur and his coworkers, Charles-Edouard Chamberland (1851-1908) and Pierre-Paul-Emile Roux (1853-1933), failed to isolate the causative agent, which they believed to be a bacteria. Studying the tissue cultures from rabid and healthy animals, they soon discovered the heaviest concentrations of the pathogen in the spinal cords of rabid rabbits. Pasteur weakened the active rabies agents by hanging the spinal cords inside glass bottles with a drying agent and waiting two weeks for the viruses to becomeinactivated. Each day during that 14-day period, he made a broth suspensionfrom the spinal cords. The 14-day-old suspension was not active, the seven-day-old suspension was more active, and the day-old suspension was very active.He began inoculating fifty dogs, using the inactive suspension first, working his way up to the most active. The inoculations had the same effect that the red-hot poker treatment had produced for the victim of the rabid wolf--it rendered the rabies virus inactive so that it could not enter the incubation stage for hydrophobia. By the time the final inoculation was given, the dogs were immune to the virus.
Pasteur was hesitant to test the vaccine on humans until July 1885 when a nine-year-old boy who had been bitten 14 times by a rabid dog was brought to him. The only chance this boy, Joseph Meister, had to stop the incubation and survive hydrophobia was from the vaccine Pasteur had developed. The treatment worked, and 23 days after being bitten, Joseph returned home, eventually returning to the Pasteur Institute in Paris where he became gate-porter. He committed suicide in 1940 after being ordered by the invading German troops to openPasteur's crypt at the Institute. Pasteur scored another victory with a 14-year-old shepherd boy who battled a rabid dog to save his five friends from the fatal bites. Six days after Jean Baptiste Jupille was wounded, he was givenvaccine treatment and survived. The vaccine's first failure was reported in1885 when Louise Pelletier died eleven days after treatment was completed. Her death, however, was not surprising since she had been bitten on the head bya mountain dog and then waited 37 days to get treatment; the incubation hadbegun before she was vaccinated. Overall, the rabies vaccine proved to be a lifesaving treatment.
Rabies is still fatal unless the antirabies vaccine is started in time. Pasteur's method for diagnosing rabies could take 10-15 days before it became apparent that treatment was necessary. By the early twentieth century, American pathologist Anna Wessels Williams introduced a diagnostic procedure by which brain smears of the suspected rabid animal could be examined and diagnosis achieved in 30 minutes. Today, researchers believe a simple eye test may detectrabies faster than the blood, skin, or saliva tests currently used. Also available today is a "preexposure" vaccine for people exposed to high-risk situations, including veterinarians, researchers, forest rangers, and travellers tomost third-world countries where rabid animals are prevalent.
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