Rabies Virus
Q1: What is Rabies virus?
- Rabies virus is a lyssavirus that belongs to the family Rhabdoviridae
- It causes rabies in mammals
Q2: Morphology of Rabies virus
- Bullet-shaped virus with a narrow tail
- Size: 75–80 nm length and 75–100 nm width
- Single-stranded RNA genome
- Lipid envelope present
- Helical nucleocapsid
Q3: Mode of transmission of Rabies
- Through saliva of infected animals usually via bite
- Through contact with infected nervous tissue such as scratch or lick
- Rarely through organ transplantation
- Rare laboratory exposure cases
- Direct contact with saliva through bites or scratches
Q4: Pathogenicity of Rabies
- Virus enters through bite wound
- Travels along peripheral nerves to CNS
- Replicates inside CNS causing inflammation and tissue damage
- Spreads to other organs including salivary glands
- Causes paralysis, neurological symptoms, and death Word trick: VIRUS → INFLAME → DAMAGE → DIE
Q5: Clinical stages of Rabies
- Incubation period 2–12 weeks or up to several years
- Prodromal phase with fever, headache, fatigue
- Furious rabies with agitation, aggression, hydrophobia
- Paralytic rabies with flaccid paralysis and weakness
- Terminal phase with coma and death
Q6: Symptoms of Incubation period
- No symptoms
Q7: Symptoms of Prodromal phase
- Fever, headache, fatigue
- Numbness or tingling at bite site
- Anxiety or agitation
Q8: Symptoms of Furious rabies
- Aggressive behavior
- Confusion and disorientation
- Hydrophobia
- Muscle paralysis
Q9: Symptoms of Paralytic rabies
- Flaccid paralysis
- Loss of coordination and balance
- Loss of sensation in face and limbs
Q10: Laboratory diagnosis of human rabies
- Detection of viral RNA in saliva, CSF, or brain tissue by PCR or RT-PCR
- Immunofluorescence test for viral antigens
- ELISA for viral antibodies
- Virus isolation from tissue samples
- Histopathology of brain for inflammation and viral replication
- Immunohistochemical staining for viral antigens Memory trick: V S R P R V – Virus isolation S – Serology R – PCR P – RT-PCR R – RNA detection
Q11: Life cycle of Rabies virus
- Attachment to host cell via glycoprotein
- Penetration by membrane fusion
- Uncoating of viral genome
- Replication of RNA and synthesis of proteins
- Assembly of new viral particles
- Release from host cell Memory trick: Aunt Betty's Poodles Run Amok, Poisoning Rabbits, Vicious Animals, People, and Others Simplified: VIRUS → WOUND → CNS → DEATH
Q12: Complications of Rabies
- Respiratory failure
- Cardiac arrest
- Seizures
- Coma
- Death
Q13: Management of Rabies
- Post-exposure prophylaxis with vaccine and rabies immunoglobulin
- Supportive symptomatic care
- Antiviral therapy in rare cases
- Intensive monitoring of neurological symptoms
Q14: Prevention of Rabies
- Vaccination of animals
- Avoiding contact with wild animals
- Wearing protective gear when handling animals
- Seeking medical help immediately after a bite or scratch