Introduction:
Rabies is a viral disease that affects the central nervous system (CNS), leading to severe neurological symptoms and almost always fatal once symptoms appear. It is caused by the rabies virus and is primarily transmitted through the bite of an infected animal.
Causes and Transmission:
Causative Agent:
Rabies virus (Genus: Lyssavirus).
Mode of Transmission:
Animal bites or scratches (especially from infected dogs, bats, foxes, or raccoons).
Contact with infected saliva on open wounds or mucous membranes (eyes, nose, mouth).
Rare: Inhalation of aerosolized virus (e.g., in bat caves).
Pathogenesis:
Entry: Virus enters through the wound.
Nerve infection: Travels via peripheral nerves to the spinal cord and brain.
CNS involvement: Causes severe encephalitis (brain inflammation).
Spreads to organs: Particularly affects the salivary glands, facilitating transmission through saliva.
Symptoms:
Incubation Period:
Usually 1-3 months but can range from 1 week to 1 year.
Early Symptoms:
Fever, headache, weakness, malaise.
Discomfort or itching at the site of the bite.
Advanced Symptoms:
Neurological Phase:
Anxiety, confusion, agitation.
Hallucinations and hydrophobia (fear of water due to painful swallowing).
Excessive salivation ("foaming at the mouth").
Paralytic Phase:
Paralysis begins, leading to coma.
Death usually occurs within 7-10 days of symptom onset.
Diagnosis:
Clinical Diagnosis: Based on symptoms and history of animal bite.
Laboratory Tests:
Direct fluorescent antibody (DFA) test on brain tissue (post-mortem).
RT-PCR to detect viral RNA in saliva or cerebrospinal fluid.
Skin biopsy (presence of virus in hair follicles).
Treatment:
No effective treatment once symptoms appear.
Palliative care: Supportive care in isolation to ease suffering.
Prevention:
Post-Exposure Prophylaxis (PEP):
Immediately clean the wound with soap and water.
Rabies immunoglobulin (RIG): Administered near the wound.
Series of rabies vaccines given over 14 days.
Pre-Exposure Prophylaxis (PrEP):
Recommended for individuals at high risk (e.g., veterinarians, travelers to endemic areas).
Control of Rabies in Animals:
Vaccination of pets (dogs and cats).
Wildlife management: Oral rabies vaccines for wild animals.
Global Impact:
Epidemiology:
More than 59,000 deaths annually, mostly in Asia and Africa.
Children are the most affected group.
High-Risk Regions:
Rural areas with large populations of unvaccinated dogs.
Conclusion:
Rabies is a fatal but preventable viral disease. Immediate wound care, post-exposure prophylaxis (PEP), and vaccination of pets are crucial for prevention. Public awareness and animal vaccination programs play essential roles in reducing the global burden of rabies.