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On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 19 August, 2004 Next Week's Question
Rabies: Passed through saliva
Question
How did animals get to have rabies?

Question
Rabies is caused by a virus belonging to the family Rhabdoviridae. It was first recognized over 3000 years ago, and is now found on all continents except Australia.

A virus is a very small and simple organism that must live inside an animal to survive. It is made up of a single genetic (RNA) strand, a protein cover, and an outer envelope. Rabies is most often transmitted via saliva when an infected animal bites another animal. The rabies virus can survive and cause disease in all mammals, including humans. Once a virus is living inside of an animal, the animal is called a host.

Viruses evolve over time by changing themselves in ways that help them live inside their hosts. In the case of the rabies virus, it can replicate itself once it gets into the muscle of an animal. It can find and move up nerves within the muscle until it reaches the animal's brain and spinal cord. It is here that the effects of the virus are seen. An infection of the brain and spinal cord destroys nerves and causes the animal to become nervous, irritable, dizzy, and even aggressive ("furious rabies"). Other animals will become paralyzed ("dumb or paralytic rabies"). In either case, the nerves that control breathing are destroyed, and the animal dies of suffocation. The most important way in which the virus ensures its survival is to find a way to get out of its dying host and into another animal. The rabies virus does this by being able to spread to the infected animal's salivary glands and exiting the body when the animal injects saliva into another animal.

Because this virus has been around for so long, it has found the best ways to get to its mammal hosts, exert fatal effects, and then spread to other mammals. Our pets often become infected when they come into contact with wildlife, and infected pets may spread rabies to people through biting. This is why it is very important to bring your pets to the veterinarian regularly for check-ups and rabies vaccinations.