31 03 2011

Rabies transmission from dogs to humans has been known since ancient times. Mad dogs and their bites get a mention in the Babylonian Code of Eshnunna, dating back to 2300 BCE, when a death-dealing bite from a dog cost its owner “two thirds of a mina of silver,” or a little less than a pound of silver.

Indeed, the disease gets a mention from ancient luminaries such as Aristotle and Celsus, but it wasn’t until the 19th century that Louis Pasteur developed a way of preventing the disease in animals, taking nerve tissue from infected rabbits  and drying it out to weaken the virus for use in a vaccine. On July 6, 1885, Pasteur tried his vaccine out in a young boy who had suffered a bite from a rabid dog. The boy lived and did not develop rabies. The vaccine had been a success.

This breakthrough led to development of a vaccine for animals and a preventive vaccine for humans who had been bitten by animals suspected or confirmed to have rabies. Yet, the disease remained a fear well into the 20th century, a featured element in American literature from Old Yeller to To Kill A Mockingbird.

Even today, with widespread vaccine campaigns targeting domestic pets, rabies persists in some wild populations, such as bats, where infection rates run about 6%. Where bats occur, health officials struggle to keep the public informed, warning that no bat should ever be touched or handled because of the risk of rabies transmission. Exposure to bats can kick up during the summer months when people are outdoors more. One study found that 46% of rabies-related bites came from bats, and the huge majority of these infectious bites occur during the summer months.

Other wild animals that carry rabies include foxes, raccoons, skunks, and coyotes. And even though only 27 cases of confirmed infection have been reported in people in the United States since 1990, every year between 16,000 and 39,000 people receive treatment because of suspected exposure.

Until recently, anyone who was exposed had to undergo a series of five shots to avoid developing the disease, which is almost invariably fatal. That series can now be reduced to four.

While vaccines were once based on virus grown in nervous system tissue, today’s vaccines are instead grown in cells in culture.

It’s pretty straightforward to avoid contracting rabies, but children in particular need to be educated about the rules: avoid contact with all wild animals known to transmit the disease, including bats, foxes, coyotes, and skunks. Never touch or approach an injured animal, and if you have a domesticated pet, such as a dog or cat, be sure that Spot or Fifi is completely up to date on all vaccines.

World Rabies Day, should you wish to party down, is September 28.