What is Rabies? PDF Print E-mail




Rabies (from Latin: rabies, “madness, rage, fury.” Also known as “hydrophobia”) is a zoonotic disease (a disease that is tr ansmitted to humans from animals) that is caused by a rod or bullet-shaped virus (from the Rhabdoviridae family). It is gray when seen under an electron microscope. The virus is sensitive to sunlight, ultra-violet light, ether, formalin, mercury and nitric acid. It is resistant to merthiolate and other common anti-bacterial agents.  

Rabies infects warm-blooded domestic and wild animals, and is spread to people through close contact with infected saliva (via bites, scratches or licks on open wounds). Cases have also been reported in which the virus penetrated the body through moist tissues such as the eyes or lips or the transplantation of infected tissues. Cases of person-to-person transmission through dispersion of saliva droplets in the air have been recorded.

The rabies virus has a strong affinity for the Central Nervous System (which is made up of the brain and the spinal cord). It makes its way to the brain by following the peripheral nerves (the nerves that run throughout the body).



The virus goes through the following stages:  

  1. Attachment: The rabies virus attaches itself to a healthy nerve cell.
  2. Penetration: The virus is taken in by the cell.
  3. Replication: Inside the cell, the virus multiplies rapidly.
  4. Budding: The new rabies virus leaves the host cell. It attaches to other nerve cells. The virus then spreads from the brain to the rest of the body by the nerves.

The incubation period of the disease depends on various factors like how far the virus must travel to reach the central nervous system. In rabies, the incubation period refers to the period from the animal bite incidence to the time when signs begin to appear. Factors that may affect incubation include: extensiveness of the bite, specie of the animal, richness of the nerve supply in the affected area, and resistance of the host. It usually takes one week to seven and a half months in animals and ten days to fifteen years in humans. The disease is communicable from three to five days before onset of symptoms until the entire course of illness.

Signs and Symptoms:

Rabies in Humans

                         Once the signs and symptoms of rabies infection appear in humans, the situation becomes irreversible and death is almost always inevitable. This is why it is very important to go to the nearest animal bite center if you have been bitten, scratched or licked by an animal that might be rabid.

                   Early symptoms of rabies include fever, headache, sore throat, fatigue, loss of appetite, nausea, vomiting and diarrhea. The disease, later, progresses to involve the respiratory, gastro-intestinal and/or central nervous systems.  As the virus gets to the brain, the person may act nervous, confused, upset and violent.

 Other symptoms of rabies in humans include:

  1. pain or tingling at the site of the bite
  2. dilated or irregular pupils
  3. excessive sweating especially at the head part
  4. increased tears, low blood pressure and increase in blood sugar level
  5. sensitivity to air, to touch, to loud noises and bright lights
  6. hallucinations (for example, seeing things that are not really there)
  7. hydrophobia ("fear of water" due to painful spasms in the throat) despite extreme thirst
  8. drooling (excessive flow of foam-like saliva)  
  9. paralysis (unable to move parts of the body)

                   As the disease advances to the fatal stage, the person gets dehydrated, enters into a coma and dies.

Rabies in Animals

                   Animals with rabies may exhibit notable changes in behavior. They become either aggressive or withdrawn.  A pet that is usually friendly may suddenly snap at you and try to bite. Rabies is transmitted to other animals through contact with virus-laden saliva by biting or licking of open wounds by a rabid animal.

                   There are two common types of rabies. One type is "furious" rabies. Animals with this type are hostile, may bite at objects, and exhibit excessive salivation.  The second and more common form is known as paralytic or "dumb" rabies. An animal with "dumb" rabies is timid and shy, refuses to eat and suffers from paralysis of the lower jaw and muscles.

                     In the Philippines, the most common source of infection are dogs, followed by cats. In the United States, rabies is much more common in wild animals like raccoons, skunks, foxes and bats than in pets like cats or dogs.

Signs of Canine Rabies

There are two forms of rabies:


1.     Change from friendly disposition into wild vicious behavior; restlessness; runs around aimlessly

2.     Whining - as if in pain; Foaming of the mouth;

3.     If on leash, bites anyone or anything within its reach, if caged, bites even the cage;

4.     Difficulty in eating and drinking;

5.     Snaps at imaginary objects. 


1.     Becomes lethargic and depressed. Hides in dark, quiet places, sluggish or sleepy

2.     Refuses to eat; difficulty in swallowing, drinking and breathing

3.     Appears to be staring at a distant object (far-away look)

4.     The lower jaw drops, the tongue hangs, and the dog salivates continuously

5.     Lameness

6.     Dies suddenly without any signs

What to Do in Case of Animal Bite/Scratch/Lick on an Open Wound

1.     When exposed to or bitten by an animal (rabid or not), wash & flush the wound thoroughly with soap and water for at least five minutes.

2.     Visit the nearest Animal Bite Center for wound care or possible post- exposure vaccination.

3.     Restrain the dog with a leash or confine in a cage.

4.     Do not kill the animal.. Wait to see what happens within 14 days of the incidence to confirm if it is rabid or not. A rabid animal usually dies within the 14-day observation period. If it dies within 14 days, call a veterinarian for proper submission of sample to the nearest Animal Disease Diagnostic Laboratory.

 Reminders re: Laboratory Confirmation of Suspected Rabid Animals:

1.     The head of animals for laboratory testing should be placed in a leak-proof double plastic bag. This, in turn, should be placed in a bigger container with liberal amounts of ice. If the animal can be brought to the laboratory within 12 hours of death, ice is not needed.

2.     Do not put chemical disinfectants or preservatives such as formalin, alcohol, etc.

3.     Animals for testing should be brought to the nearest rabies diagnostic laboratory.

4.     Ensure proper care and protection when attempting to detach the head of the animal. Wear protective gear (e.g. gloves, mask, goggles) and disinfect all materials used after carrying out the procedure.



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