Disease Topics:Rabies

Rabies is a deadly virus that attacks the CNS (central nervous system) and causes acute encephalitis. It is transmitted from animals to humans (zoonotic), most commonly by animal bites - although, there have been cases of humans becoming infected in bat caves after breathing in the air.

Rabies is a viral infection spread via saliva. If someone presents with rabies symptoms, it is almost always fatal. In countries where stray dogs are present in large numbers, they are the biggest rabies threat.

Predominantly, in the US, rabies is spread by raccoons, coyotes, bats, skunks and foxes.2 Bats carrying rabies have been found in all 48 contiguous states.

Dr. Joseph Lennox Pawan first discovered animal-to-human transmission of rabies in the vampire bat in Trinidad in 1932.3

It is now known that any mammal can harbor and transmit the virus. However, smaller mammals such as rodents very rarely become infected or transmit rabies.

Symptoms of rabies

The symptoms of rabies can present themselves just a few days after a bite, or they might take as long as 12 weeks. Some rare cases report a number of years between the bite and the onset of symptoms.

The closer the bite is to your brain, the quicker the effects are likely to appear.4

If you are bitten by a wild animal, it is essential that you seek medical advice as soon as possible.

When the initial symptoms of rabies occur, they can be similar to flu and last 2-12 days, becoming progressively stronger.

From the early flu-like symptoms, the condition worsens and symptoms can include the following:

  • Anxiety
  • Fever
  • Headache
  • Nausea
  • Confusion
  • Hyperactivity
  • Excess salivation
  • Fear of water (hydrophobia) due to difficulty in swallowing
  • Hallucinations
  • Priapism (permanent erection)
  • Photophobia
  • Nightmares
  • Insomnia
  • Partial paralysis.
  • Causes of rabies

    Rabies is a virus and, as mentioned, it is predominantly spread by a bite from aninfected animal.

    However, it is also possible to become infected if saliva from an infected animal gets into an open wound or through a mucous membrane, such as the eyes or mouth.

    Tests and diagnosis of rabies

    At the time of a bite, there is no way to tell for sure whether an animal is rabid, or whether it has infected you.

    The doctor will suggest moving straight to treatment; there is no benefit in waiting.

    Rabies progression.

    The rabies virus is an RNA virus in the rhabdovirus family. The virus has five distinct stages:

    • Incubation period: this can vary in length exceptionally, from days to years
    • Prodrome: early flu-like symptoms
    • Acute neurologic period:neurological symptoms begin. These can include hyperactivity, or paralysis, as well as rigid neck muscles, involuntary muscle twitching, convulsions, hyperventilation and hypersalivation. Toward the end of this phase, breathing becomes rapid and inconsistent
    • Coma: unless attached to a ventilator, death will come within a matter of hours
    • Death: or, rarely, recovery.5

    The rabies virus can enter the peripheral nervous system directly and migrate to the brain, or it can replicate within muscle tissue (safe from the host's immune system) and enter the nervous system through the neuromuscular junctions.

    Once within the nervous system, the virus produces acute inflammation of the brain, swiftly causing coma followed by death.

    Treatment for rabies

    As the disease is generally fatal (although a small number of people have survived), there is no treatment for the illness per se. Once symptoms have arisen, there are no medications that can provide help.

    As soon as a bite is received, a series of shots will be prescribed to prevent the virus from thriving. The shots include:

    • A fast-acting shot consisting of rabies immune globulin; this will prevent the virus from infecting the individual and will be delivered as soon as possible, close to the bite wound.
    • A series of rabies vaccines to train your body to fight the virus whenever it finds it. These will be given over the following 2 weeks and delivered into the arm.

    Rabies used to be referred to as hydrophobia because of the fear of water produced in sufferers. Intense spasms in the throat are triggered when trying to swallow. In fact, the spasms can be triggered by the mere thought of swallowing water, hence the fear.

    Excess saliva is produced, probably due to the rabies virus assimilating in the salivary glands. If the individual were able to swallow saliva easily, the virus' chance of moving to a new host would be minimized.


        Prevention of rabies (for individuals)

     The following are general safety rules to lessen your chances of contracting rabies:

  • Vaccinate pets: cats, dogs and ferrets can all easily be vaccinated, preventing them from catching and passing the virus on
  • Keep pets confined: ensure pets are safely confined and supervised when outside
  • Report stray animals to local authorities: local animal control officials or police departments can remove any animals seen roaming
  • Do not approach wild animals: animals with rabies are less cautious and more likely to approach you
  • Keep bats out of the home: seal your home to prevent bats from nesting. If bats are already present, experts can safely remove them
  • Wash the wound: if you have been bitten, washing bites and scratches for 15 minutes with soapy water, povidone iodine or detergent might minimize the number of viral particles (medical help should still be sought)
  • Vaccination: if you have plans to travel, especially in Africa or India, vaccination is a good idea.

Prevention of rabies (countrywide)

Because rabies is such an adept killer, many nations have carried out projects in an effort to wipe out, or at least minimize, the amount of rabies in their animal populations. 

These projects can includewidespread vaccinations of humans in affected areas or simply the dissemination of educational information to remote populations.


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