Rabies :Transmission and Clinical features

Rabies :Transmission and Clinical features


RABIES

  • It is the communicable disease which is always fatal.(100% morality)
  • Rabies is an enzootic and epizootic disease of world-wide importance.
  • Diseases under international surveillance (WHO)

DISTRIBUTION

  • Geographic boundries play  role in the distribution of rabies.
  • Water appears to be the most effective natural barriers to rabies.
  • In India, Lakshadweep and Andman & Nicobar islands are free of the disease.
  • A Rabies free area has been defined as one in which no case of indigenously acquired rabies has occurred in man or any animal species for 2 years.
  • Countries where rabies is not found
  1. Australia 
  2. China (Taiwan),
  3. Cyprus
  4. Iceland
  5. Ireland
  6. Malta
  7. Japan
  8. Newzealand,
  9. Britain.

MODE OF TRANSMISSION

  • Bite of rabid dogs or other animals (Most common)
  • Non bite exposure
  1. Licks or aerosols
  2. Transplantation of cornea.

PATHOGENESIS

  • Enters the peripheral nervous system (PNS) directly
  • Migrates to the brain.
  • It replicates within muscle tissue, where it is safe from the host’s immune system
  • Enters the nervous system through the neuromuscular junctions.
  • Produces acute inflammation of the brain
  • Brain stem encephalitis
  •  Coma and death soon follow.

TYPES

 Furious, or encephalitic rabies

  • This occurs in 80 percent of human cases.
  • The person experience hyperactivity
  • Headache, fever, irritability, restlessness and anxiety.
  • Dilated pupils
  • Muscle pain
  • Vomiting
  • Salivation
  • Hydrophobia
  • Phase coninue 
  • Coma
  • Death

Paralytic or “dumb” rabies

  • Patient experiences depression
  • Paralysis followed by a coma. 
  • Death eventually results from respiratory arrest.

SYMPTOMS

Five stages

  • incubation
  • prodrome
  • acute neurologic period
  • coma
  • death

Prodrome

  • Early, flu-like symptoms
  • Fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or above
  • Headache
  • Anxiety
  • Feeling generally unwell
  • Sore throat and a cough
  • Nausea and vomiting
  • Discomfort at the site of the bite
  • Last from 2 to 10 days, and they worsen over time.

Acute neurologic period

  • Neurologic symptoms develop
  • confusion and aggression
  • partial paralysis, involuntary muscle twitching, and rigid neck muscles
  • convulsions
  • Toward the end of this phase, breathing becomes rapid and inconsistent.
  • hyperventilation and difficulty breathing
  • hypersalivation
  • frothing at the mouth
  • Hydrophobia
  • Hallucinations, nightmares, and insomnia
  • Priapism, or permanent erection, in males
  • Photophobia, or a fear of light

Coma and death

  • Person enters a coma
  • Death will occur within a matter of hours, unless they are attached to a ventilator.
  • Rarely, a person may recover at this late stage.

Why does rabies cause a fear of water?

  • Rabies used to be known as hydrophobia
  • Cause a fear of water.
  • Intense spasms in the throat are triggered when trying to swallow.
  •  Even the thought of swallowing water can cause spasms.
  • This is where the fear comes from.
Exam Question
 

RABIES

  • It is the communicable disease which is always fatal.(100% morality)
  • Rabies is an enzootic and epizootic disease of world-wide importance.
  • Diseases under international surveillance (WHO)

DISTRIBUTION

  • Water appears to be the most effective natural barriers to rabies.
  • In India, Lakshadweep and Andman & Nicobar islands are free of the disease.
  • A Rabies free area has been defined as one in which no case of indigenously acquired rabies has occurred in man or any animal species for 2 years.
  • Countries where rabies is not found  
  1. Australia 
  2. china (Taiwan)
  3. Cyprus
  4. Iceland
  5. Ireland
  6. Malta
  7. Japan
  8. Newzealand
  9. Britain

MODE OF TRANSMISSION

  • Bite of rabid dogs or other animals (Most common)
  • Non bite exposure
  1. Licks or aerosols
  2. Transplantation of cornea.

PATHOGENESIS

  • Enters the peripheral nervous system (PNS) directly
  • Migrates to the brain.
  • It replicates within muscle tissue, where it is safe from the host’s immune system
  • Enters the nervous system through the neuromuscular junctions.
  • Produces acute inflammation of the brain.
  • Rabies prominantly infect neurons
  • Brain stem encephalitis
  • Centrifugal spread to other tissues including
  • salivary gland
  • heart
  • adrenal gland
  • skin
  • Coma and death soon follow.

TYPES

 Furious, or encephalitic rabies

  • This occurs in 80 percent of human cases.
  • The person experience hyperactivity
  • headache, fever, irritability, restlessness and anxiety.
  • Dilated pupils
  • Muscle pain
  • Vomiting
  • Salivation
  • Hydrophobia
  • Phase coninue 
  • Coma
  • Death

Paralytic or “dumb” rabies

  • Patient experiences depression
  • Paralysis followed by a coma. 
  • Death eventually results from respiratory arrest.

SYMPTOMS

Five stages

  • incubation
  • prodrome
  • acute neurologic period
  • coma
  • death 

Why does rabies cause a fear of water?

  • Intense spasms in the throat are triggered when trying to swallow.
  • Even the thought of swallowing water can cause spasms.
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