Rabies is one of the deadliest known viruses. People who work closely with wildlife, veterinarians, and travellers are at the highest risk of exposure. Fortunately, there is a vaccine that is available to protect high-risk people as well as animals.


Transmission of the virus
The transmission of the disease almost occurs as a result of an infected animal biting a non-infected animal. Skunks, raccoons, foxes, and bats are the animals likely to transmit the virus. The rabies viruses are shed at high levels in saliva. However, being bitten by a rabid animal does not necessarily mean that the bitten animal (or human) will become infected.

Signs and Symptoms
After coming in contact with the virus, the bitten animal may go through one or all the stages. With most animals, the virus will spread through the nerves towards the brain. The virus is relatively slow and incubation period is between 3 to 8 weeks in dogs, 2 to 6 weeks in cats, and 3 to 6 weeks in humans. After the virus reaches the brain it then moves to the salivary gland. Once the virus reaches the brain, the animal will exhibit one or all the phases discussed below.

  • Prodromal phase: This phase usually lasts for 2-3 days in dogs. Apprehension, nervousness, anxiety, solitude, and fever are the common signs. Most animals will lick the site of the bite. In cats, this phase lasts for 1-2 days and they usually develop more fever spikes and erratic behaviour than dogs.
  • Furious phase: This phase usually lasts for 1-7 days for dogs. They become restless, irritable and are hyper-responsive to auditory and visual stimuli. Because of the restlessness, they roam around feeling agitated and irked.
  • Paralytic (dumb) phase: The phase develops within 2-4 days after the first signs are seen. Deep laboured breathing and a dropped jaw may result as the diaphragm and facial muscles become increasingly paralysed. The animal will get weaker and eventually go into respiratory failure and die.

Diagnosis
The current way to diagnose rabies in animals is to submit brain tissue from two locations in the brain (preferably the brain stem and cerebellum) for microscopic examination. Some new tested techniques utilizing skin and or blood samples are being studied upon.

(Dr Rabyia Javed is PhD scholar at College of Veterinary Sciences, Ludhiana; Dr Rakhi Gangil and Dr Deepak Gangil are Assistant Professors at College of Veterinary Sciences, Mhow).


Prevention
Vaccination is the best way to prevent infection and properly vaccinated animals stand very little chance of contracting the disease. The standard vaccination protocol is to vaccinate cats and dogs at three or four months during the first year and then again at one year of age. A year later, a three-year rabies vaccination is recommended, which is known to be effective.