rabies

• rabies: The most significant pathogen of the Rhabdoviridae family

  • "rhabdos" means rod
  • has 30 genera
  • 2 important genera:
  • vesiculoviruses (VSV) - vesicular formation
  • lyssaviruses (LSV) - where rabies belongs
• physiology, structure and replication

  • bullet-shaped enveloped virions
  • 50-95 nm in diameter: 130-380 nm in length
  • negative-sense RNA genome
  • 5 rabies genome found in glycoprotein spike of the virus
• • Glycoprotein of rabies virus Attaches to the nicotinic acetylcholine receptor or neural cell adhesion molecule

  • It targets nerve cells (brain and spinal cord)

  • Replication in cytoplasm

  • Membrane proteins:

  • N- nucleocapsid

  • L, P – polymerase proteins

  • M–matrix
• Rabies is primarily transmitted through direct contact (such as through broken skin or mucous membranes in the eyes, nose, or mouth) with saliva from an infected animal from bite or licking

  • Other ways:

  • Inhalation of aerosolized virus

  • Transplantation of infected organ
• Incubation Phase

  • Virus replicates in the muscle at the site of the bite with minimal or no symptoms
  • Length of incubation will depend on:
  • Concentration of the virus in the inoculum
  • Proximity of the wound to the brain
  • Severity of the wound
  • Host’s age
  • Host’s immune system
• Incubation Phase

  In humans, its usually 1-3 months but may be as short as 1 week to as long as 1 year

  In dogs, it can range from 3-8 weeks and as short as 10 days
• Prodrome Phase

  • Virus infects the peripheral nerves and travels up to the CNS and brain

  • Retrograde axosplasmic transport
• 3 phases of rabies: incubation, prodrome, neurologic
• Prodrome phase

  • May show symptoms such as: malaise, anorexia, headache, photophobia, nausea, and vomiting, sore throat, and fever
  • Abnormal sensation in wound site
• Neurologic Phase

  • 2-7 days
  • Nervousness, apprehension, hallucinations, and bizarre behavior
  • Spreads to the glands, skin and other parts like salivary glands
  • Lacrimation, pupillary dilatation and increased salivation and perspiration
• neurologic phase

  • Hydrophobia - fear of water
  • Aerophobia - fear when feeling a breeze
  • Results to encephalitis and neural degeneration
• Prodrome Phase

  • Rabies is always fatal unless treated with vaccination
  • Non specific symptoms
• Neurologic phase 

  • Paralysis - respiratory failure
  • Eventually leads to coma and death
• Immunity 

  Rabies infection 

  • Antibodies are not produced until the late stages of disease
• immunity

  Rabies vaccine

  • Administration can block progression of the virus if early given
• Laboratory diagnosis

  • Antigen detection: ELISA and immunofluorescence
  • Genome detection: RT-PCR 
  • Gold standard: fluorescence antibody test 
  • Biopsy: Negri bodies 
  • Sample: Saliva, serum, CSF, skin biopsy of the nape, brain biopsy  
• Management

  • Protective measure

  Local treatment wound

  Wash soap and water

  Pain control

  • Post Exposure prophylaxis

  Anti rabies immunoglobulins

  • Animal control