Rabies

• Rabies - Zoonotic Viral disease
• Rabhas means - violence
• Lyssavirus

  • the causative agent for rabies that has been found on all continents.
• Modes of Transmission

  • Direct Contact between infectious material typically saliva and human mucosa.
  • Mucosa includes areas such as the eyes, nose, and mouth.
  • Fresh skin wounds serve as a portal of entry.
• Virus Entry


  Enters through bite or scratch of infected animals
• Furious Rabies

  • Results in hyperactivity, excitable behavior, hallucinations, lack of coordination, hydrophobia, and aerophobia (fear of drafts or freshwater).
  • Death occurs after a few days due to cardio-respiratory arrest.
• Local Replication


  1. The virus replicates near the site of the bite or scratch in muscle cells

  2. Typically without symptoms, lasting days to months
• Peripheral Nervous System Invasion


  Travels along peripheral nerves to the central nervous system, moving from the site of infection toward the spinal cord and brain
• Paralytic Rabies

  • It presents with a less dramatic and unusually longer course compared to the furious form.
  • Muscle paralysis begins gradually, starting from the wound site.
  • Patients may develop a coma over time, leading to eventual death.
• Central Nervous System Infection


  Infects neurons, primarily the brainstem with potential spread to other brain regions like limbic system and cerebral cortex
• Prodromal Phase


  Onset of clinical symptoms
• Fluorescent Antibody Test (FAT)

  • The most widely used primary diagnostic test for rabies in both animals and humans.
  • Based on antigen detection and looks for the presence of rabies antigens in brain tissue.
• Viral Spread


  Spreads within the CNS through neural pathways and direct extension, causing disruption of normal neuronal function and neurological symptoms
• Virus Replication: Inoculation Tests

  • Aim to detect virus replication on living substrates such as cells.
  • Introducing the virus into an animal model, usually through injection or exposure to infected tissue, and then observing the progression of the disease.
• Neurological Symptoms


  • Agitation and anxiety
  • Confusion and hallucinations
  • Difficulty swallowing (hydrophobia)
  • Excessive salivation (hypersalivation)
  • Muscle spasms particularly in the throat and jaw
  • Paralysis
  • Seizures
  • Coma
• Inflammation and Immune response


  1. Induces inflammation in the CNS, resulting in neuronal degeneration and inflammations

  2. Although, the immune response if often insufficient to clear the virus from the CNS
• The Reverse Transcriptase (RT) Polymerase Chain Reaction (PCR

  • Includes sample collection, RNA extraction, reverse transcription, PCR amplification, detection.
  • Enhances sensitivity and provides faster results compared to traditional PCR methods.
  • Offer the highest sensitivity for detecting rabies virus RNA.
• Death often results from respiratory failure or cardiac arrest due to paralysis
• Serological Test

  • Not suitable for all diagnoses.
  • Virus-specific antigbodies in serum typically appear relativles late after the onset of clinical signs.
  • These tests are primarily used to assess the immune response to human and animal rabies vaccines.
• Postexposure Prophylaxis (PEP)

  • Consists of wound cleaning and a dose of human rabies immune globulin (HRIG) and Rabies Vaccine.
  • Doses of vaccine for Rabies Vaccine is on the of the rabies exposure. Then given again on 3rd, 7th, and 14th day.
  • For people who are never been vaccinated, postexposure prophylaxis should always include administration of both HRIG and rabies vaccine.
• PrEP

  • recommended for high risk occupations.
  • involves administering the rabies vaccine series before potential exposure to the virus to provide immunity in case of subsequent.
• PEP

  • involves administering the rabies vaccine series after potential exposure to prevent the development of rabies infection.
  • essential for those who have been bitten or scratched by a potentially rabid animal or who have direct contact with animal’s saliva or neural tissue.