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Tuesday, September 1, 2015

Rabies ::

Rabies is a viral disease of Central Nervous System that spreads through the bite of an infected warm-blooded animals. It is also known as 'Hydrophobia'. Transmission can also occur through saliva touching an open wound or touching mucous membranes.
1. About 60,000 people die every year of rabies, mostly in Asia and Africa.
2. In the U.S., one to three people die from rabies each year.
3. Animal vaccinations and postexposure prophylaxis protocols have nearly eradicated rabies in the U.S.
4. Every year more than 15 million people worldwide receive postexposure vaccination to prevent rabies.

✿ Rabies is caused by the rabies virus (lassaviirus Type-1).
✿ The virus infects the brain and ultimately leads to death.
✿ After being bitten by a rabid animal, the virus is deposited in the muscle and subcutaneous tissue.
Mode of Transmission
- Animal bite i.e Dogs, cat, monkeys, cow, goat, sheep, horses.
- Licks (on abraded skin or abraded unabraded mucosa)
- Aerosols (Rabies infected bats)
- Person to person (rare but possible)
- Organ transplantation.
Incubation Period
✔ It depends on the site of the bite, severity of the bite, number of wounds, amount of virus injected.
✔ Commonly 3-8 weeks (minimum 9 days).

Symptoms can occur as fast as within the first week of the infection.
The early symptoms of rabies are very generalized and include weakness, fever, and headaches. Without a history of a potential exposure to a rabid animal, these symptoms would not raise the suspicion of rabies as they are very similar to the common flu or other viral syndromes.
The disease can then take two forms:
  1. With paralytic rabies (approximately 20% of cases), the patient's muscles slowly get paralyzed (usually starting at the site of the bite), is the less common form and ends incoma and death.
  2. With furious rabies (about 80% of cases), the patient exhibits the classic symptoms of rabies, such as
    • anxiety and confusion (The patient is often overly active.);
    • encephalitis, causing hallucinations, confusion, and coma;
    • hypersalivation;
    • hydrophobia (fear and avoidance of water);
    • difficulty swallowing.
Once the clinical signs of rabies occur, the disease is nearly always fatal.

How do physicians diagnose rabies?

In animals, rabies is diagnosed by detecting the rabies virus in any affected part of the brain. This requires that the animal be euthanized. Testing a suspected animal will help avoid extensive testing in the human contact (if the test is negative) and unnecessary treatments.
In humans, rabies is diagnosed by testing saliva, blood samples, spinal fluid, and skin samples. Multiple tests may be necessary. The tests rely on detection of proteins on the surface of the rabies virus, detection of the genetic material of the virus, or demonstration of an antibody (immune) response to the virus.

What is the treatment for rabies?

Treatment is recommended if a health-care professional thinks that someone was exposed to a potentially rabid animal.
If the animal is a pet or farm animal that has no symptoms, the animal can be isolated and observed for 10 days. Wild animals that can be captured can be killed and tested for the virus. If the animal can't be found, it is best to consult with the local health department.
The general pathway to determine postexposure prophylaxis (protective treatment) for rabies requires the following information:
  • Bite: Did a bite occur, and where is the location of the bite? (Any penetration of the skin is considered a bite; although bites to the face and hands carry the highest risk, all bites need to be considered for prophylaxis.)
  • Non-bite incident: Did the saliva touch an open would or a mucous membrane?
  • Animal risk factors: No cases of rabies infection have been reported in the U.S. from fully vaccinated domestic dogs or cats.
  • Bats: Any contact with a bat that leads to a potential scratch, bite, or mucous membrane exposure to saliva needs to be evaluated. If prolonged exposure to a bat is discovered (sleeping in a room where a bat is found), postexposure prophylaxis needs to be considered.
As rabies is a fatal disease, it is often best to start the series of shots until further information is available.
A series of injections is given. The first is a rabies immune globulin that helps to prevent the virus from infecting the individual. Part of this immunization is given near the animal bite.
This is followed by four injections over the next two weeks. These are rabies vaccines to help the body fight the virus.

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