What are the symptoms of rabies?

Symptoms of Rabies

Rabies presents with two main clinical forms: furious (encephalitic) rabies, which accounts for 80% of cases, and paralytic (dumb) rabies, which accounts for 20% of cases. 1, 2

Clinical Course of Rabies

Rabies infection typically progresses through five distinct stages:

1. Incubation Period

   • Highly variable: 2 weeks to 6 months (average 2-3 months)
   • Can rarely extend up to 6 years
   • Patient remains asymptomatic during this period 3, 4

2. Prodromal Period

   • Nonspecific constitutional symptoms:
     • Fever
     • Malaise
     • Headache
     • Fatigue
     • Anxiety
     • Irritability
   • Paresthesia, itching, or pain at the bite site (highly suggestive)
   • Lasts 2-10 days 5, 4

3. Acute Neurological Phase (manifests as either furious or paralytic form)

   Furious Rabies (80% of cases):

   • Hydrophobia (pathognomonic): terror and spasms of inspiratory muscles triggered by attempts to drink
   • Aerophobia: similar spasms triggered by air currents
   • Episodes of generalized arousal or hyperexcitability
   • Hallucinations and maniacal behavior
   • Hypersalivation
   • Tachycardia
   • Hyperpyrexia
   • Lasts 2-7 days 1, 2, 4

   Paralytic Rabies (20% of cases):

   • Progressive flaccid paralysis (ascending pattern)
   • Weakness beginning at bite site
   • Sphincter involvement
   • Sensory disturbances
   • May be confused with Guillain-Barré syndrome
   • Longer illness duration than furious form 1, 6, 4

4. Coma

   • Progressive deterioration to coma
   • Multiple organ failure in aggressively managed patients
   • Cardiopulmonary complications common 2

5. Death or Rare Recovery

   • Almost always fatal once symptoms appear
   • Death usually occurs within 7-14 days after symptom onset 1, 5

Key Diagnostic Features

• Hydrophobia and aerophobia are pathognomonic for rabies
• History of animal bite (especially from wild animals like bats, foxes, raccoons, skunks)
• Progressive neurological symptoms
• Brainstem involvement is common in both clinical forms
• Laboratory confirmation through:
  • Direct fluorescent antibody test of brain tissue
  • PCR of saliva, CSF, or tissue
  • Detection of rabies antibodies in unvaccinated patients 1

Common Pitfalls in Diagnosis

1. Misdiagnosis of paralytic rabies as Guillain-Barré syndrome, particularly when no history of animal bite is reported
2. Overlooking rabies in patients with altered mental status without obvious hydrophobia
3. Failing to consider rabies in cases of unexplained encephalitis, especially with history of travel to endemic areas
4. Missing bat bites, which can be minor and go unnoticed 7, 6

Prevention

Prevention is critical as rabies is almost always fatal once symptoms develop:

• Prompt wound cleansing with soap and water for 15 minutes
• Post-exposure prophylaxis with rabies vaccine and human rabies immune globulin for high-risk exposures
• Pre-exposure vaccination for high-risk individuals (animal handlers, laboratory workers, travelers to endemic areas) 7

Remember that rabies is invariably fatal once clinical symptoms appear, making early recognition and prevention through post-exposure prophylaxis the only effective approach to managing potential rabies exposures.