Because of threat of rabies, be cautious around wildlife

"How do bats get rabies?" asked Connor Robinson, 12, a seventh-grader at Libertyville's Highland Middle School.

There are recorded observations of the rabies virus that are more than 4,000 years old. Any mammal can contract rabies, which is passed through saliva. The virus does not survive outside of the body.

Rabies is the most deadly virus, meaning that once infected, an animal will usually die since it won't receive treatment. People can be successfully treated with the rabies vaccine. If someone is bitten or scratched by a wild animal and a health professional has determined that rabies has been transmitted, the patient can be treated with a series of vaccines.

Prevention is possible as well. Domesticated animals - dogs and cats - are given the rabies vaccine to prevent them from passing on the virus. Rabies vaccinations for dogs and cats is required by law in all states.

Once inside the body, rabies travels through nerve cells to the brain and then throughout the central nervous system. This causes muscle spasms, excessive spitting and vomiting. One strain of rabies causes infected animals to exhibit wild, out-of-control behavior, biting other animals or people nearby. When they bite, their saliva passes on the virus. Another form of the virus makes wild animals appear tame. They may seem uncharacteristically slow or sleepy. Knowing how dangerous an illness like rabies is, you should never approach a wild animal.

The serious nature of the virus - it kills its victims if they don't receive treatment - spurred one scientist to create a breakthrough discovery. Louis Pasteur, a French scientist who lived in the 1800s, was challenged to cure a child who had been bitten by a rabid dog. He took the live virus from an infected dog and injected it into the patient. The boy developed an immunity and was cured. Pasteur's vaccine prompted other scientists to develop vaccines to treat other serious illnesses.

"Before the vaccine laws in the 1940s and 1950s, the most commonly affected species were dogs. Now we see rabies most commonly in wildlife, mostly in raccoons," said Dr. Tom Meehan, veterinarian at Brookfield Zoo. "If you look at a map of the U.S., 92 percent of rabies cases are found in wildlife, because there are vaccines for pets."

Dr. Meehan said that more people are affected by rabies acquired from bats than from any other wild animal, even though rabies is less common in bats than in other mammal species. He said this is because people can easily recognize when a wild animal has unusual behavior, but bats are not as visible or obvious. "You might not be aware of a bat bite. People need to be cautious. If you see one flying around in the daytime, or laying on the ground, it's more likely to have rabies."

Bats live in close quarters, often in colonies in caves. So why doesn't the entire colony become infected with rabies and die?

"Even the most lethal viruses don't cause 100 percent mortality (death) as animals may not receive a lethal infectious dose or may have immunity from a previous exposure. With bats, the main reason that the entire colony isn't wiped out is that the disease does not affect a great percentage of the colony and is just being maintained in a certain percentage over time."

Bats at the Brookfield Zoo will not pass along rabies. The exhibits are designed to separate bats from the viewing public. Some bat species are not at risk for rabies, like the Rodrigues Fruit Bats in the Australia exhibit.

Check these out

The Cook Memorial Library in Libertyville suggests these titles on rabies:

• "World's Worst Germs: Microorganisms and Disease," by Anna Claybourne

• "Rabies," by Elaine Landau

• "Rabies," by Thomas E. Kienzle

• "Germ Hunter: A Story about Louis Pasteur," by Elaine Marie Alphin

• "Louis Pasteur: Father of Modern Medicine," by Beverley Birch

• Centers for Disease Control information for kids: cdc.gov/ncidod/dvrd/kidsrabies

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