Rabies

Written by Dr. Gregory Bartha

If you travel to Uganda you will see free roaming dogs everywhere. And with dogs come bites and with bites comes rabies. About 500 cases of rabies are reported each year in Uganda. Not only dogs but also raccoons, skunks, jackals, hyenas, even cows and goats have been known to transmit the disease. Not all animals with rabies are violent. Some are withdrawn and appear to be ill. The virus remains in the muscles near the bite wound for a short time then travels up the nerves eventually reaching the brain or spinal cord. Symptoms may occur days or months after the exposure and include abnormal behavior, hallucinations, and hydrophobia. There is progression to coma and death.

The person who is bitten should wash the wound vigorously with soap and water. The animal should be confined and observed for at least ten days. If the animal cannot be isolated or escapes, the bite victim must be treated. A vaccine is available and should be administered on the day of the bite, then 3, 7, and 14 days later.Best practice is to give rabies immune globulin together with the first dose of vaccine.

The vaccine was developed by Louis Pasteur in the 19th century. He infected rabbits with the virus by injecting nerve tissue from rabid dogs close to the spinal cord or lower part of the brain in the rabbits. When a rabbit developed signs of rabies, he took a small piece of nerve tissue from the animal and placed it in a flask in which most of the air had been removed. The longer the tissue remained in the flask the less virulent or weaker it became.

He then gave a dog a series of injections with the tissue beginning with the least virulent specimen, the which had been in a flask the longest. In each successive injection he used pieces of tissue closer to the time they were harvested. Finally he gave the dog an injection with the most virulent tissue, the one closest to the time of the harvest. The dog did not get rabies after this last injection because its immune system had been primed to recognize and destroy the virus.

One day when Pasteur was finishing with these experiments, a 9 year old boy was brought to him. The boy had been severely bitten by a rabid dog and had multiple bite wounds. Over the next 2 weeks he was given a series of injections with nerve tissue from a rabbit infected with rabies, starting with the least virulent specimen and ending with the most virulent.

The boy was examined closely for months. He never showed any sign of rabies and was pronounced free of the disease. This event was widely proclaimed as a great scientific advance and made Pasteur world famous.

Today bats are becoming more frequently implicated in cases of rabies. Again the best way to manage an animal bite is to clean the bite wound carefully, isolate and observe the animal, and begin vaccination if appropriate.

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