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Rabies

Rabies; Hydrophobia; Lyssa
Rabies Virus Rabies Virus All warm bloodied animals can catch rabies. Humans normally catch it via the bite of an infected animal such as a wild dog. It is caused by the virus rhabdovirus, which normally infects the salivary glands which is why the disease is passed on during biting.

When the virus enters the bite wound in then infects local nerve tissue. From there, it propagates along the nerve tissue. It infects the whole nervous system and eventually the brain.

The first symptom of rabies is usually excitability. This also leads to vicious tendencies also. Animals in the early stages of rabies infection are often the most dangerous. They show no obvious signs of infection. Yet, their excitability leads them to bite at the tiniest provocation. Rabies is also known as "hydrophobia" because one symptom is a fear of water. On swallowing there can be a painful contraction of the throat muscles. The "hydrophobia" name comes about because this reaction sometimes occurs at the mere sight of water. Another common symptom is paralysis, and abnormal sensations at the bite point. Convulsive seizures are common in rabies infected people. If untreated, death usually occurs within 3-5 days during a seizure.

If one is bitten by a rabid animal it is important to immediately clean the wound, (with soap and water). This will prevent most of the virus from actually entering the system. Treatment is then required within 24 hours. There are serum treatments available but after 3 days these will have little or no effect. These are produced by immunizing an animal with attenuated rabies then taking its blood serum.

There are also vaccines available for prevention of rabies. Two common ones are human diploid-cell vaccine (HDCV) and rabies vaccine adsorbed (RVA). These are both normally effective after just a couple of doses. They are also used to treat rabies infected people after the serum has been applied. (In this case the patient requires about half a dozen doses.)