Rabies

Rabies is a deadly disease that has haunted mankind for centuries—and continues to do so even today. Known since medieval times, this fetal illness is primarily caused by animal bites, particularly from dogs. The disease is even more dangerous because once the symptoms of the disease develop, there is little to no room for rabies treatment. Fortunately, the disease can be fully prevented with effective measures, which we are going to talk about here. 

1.0What is Rabies?

Rabies is a viral zoonotic disease, that is, the disease is transferable from animals to human beings. The disease results in acute encephalitis, which is brain inflammation. It infects mammals, which include human beings, and is nearly always fatal if left without treatment. The virus that causes the disease is the rabies virus, which is a bullet-shaped, single-stranded RNA virus belonging to the Lyssavirus genus within the Rhabdoviridae family.

Upon entry into the human body, the rabies virus moves along the peripheral nerves to the brain. It results in serious damage to the nerve cells and fatal complications if left untreated. The disease is rated 100% preventable when appropriately treated with wound care and early vaccination.

2.0Causes and Transmission 

The primary cause of rabies is a bite from an infected animal. These animals carry the virus in their saliva, which leads to the potential transfer of this virus when they bite or scratch. Although dogs are predominant carriers of this virus, other animals such as bats, raccoons, foxes, and skunks play a major role in spreading rabies. 

Other Common Routes of Transmission 

• Apart from dogs, bats have also become a major cause of transmission of rabies in many parts of the world. 
• Though rare, consuming virus-containing aerosols, or raw meat or milk of an infected animal, is also possible. 
• Human-to-human transmission of rabies via organ transplantation, bites, or saliva is theoretically possible but has never been seen. 

3.0Pathogenesis: How Rabies Virus Spreads in the Body

Pathogenesis of rabies is the sequential process by which the rabies virus migrates within the host body following an animal bite and causes a deadly brain infection, and ultimately renders the host infectious. Here’s how the virus hinders the normal functioning of the brain and nervous system: 

1. Virus Entry: Rabies virus enters the body via an infected animal's bite or scratch.
2. Local Replication: The virus initially replicates within the muscle cells around the bite area.
3. Nerve Invasion: It then invades peripheral nerves and moves towards the central nervous system (CNS).
4. CNS Entry: The virus enters the spinal cord and brain through nerve routes (retrograde transport).
5. Brain Replication: Within the brain, it replicates in regions such as the amygdala and hippocampus, leading to alterations in behaviour.
6. Symptom Onset: Brain malfunction results in rabies symptoms such as hydrophobia, aggression, and confusion.
7. Spread to Organs: The virus spreads from the brain to other organs, particularly the salivary glands.
8. Saliva Hypersecretion: Salivary glands are induced to secrete copious amounts of saliva to facilitate viral transmission.
9. Transmission Behaviour: Hydrophobia and profuse saliva enhance the likelihood of biting.
10. Fatal Stage: After symptoms, the disease runs its course to coma and death. At this stage, rabies treatment fails.

4.0Rabies Symptoms 

Understanding the symptoms of rabies is vital, as it can help to make informed decisions in an emergency. The rabies symptoms are broadly classified into early and advanced stages, which include: 

1. Early (Prodromal) Symptoms: The early symptoms of rabies disease include: 

1. Fever and headache

2. Discomfort or tingling sensation at the bite site. 

3. Fatigue and nausea

4. Anxiety and irritability

2. Advanced (Neurological) Symptoms: Rabies is a fast-infecting disease that, once infected, spreads very quickly and reaches the advanced stage, symptoms of which are: 

1. Muscle spasms

2. Hydrophobia (fear of water)

3. Hallucinations

4. Aggression or paralysis

5. Respiratory failure leading to death

5.0Rabies Vaccine and Prevention

Rabies vaccine is the most effective known tool against rabies, with an almost 100% success rate, if used promptly. The vaccine is used as: 

Pre-exposure Prophylaxis 

When the rabies vaccine is given prior to exposure to the virus: 

• Generally, recommended for veterinarians, animal handlers, and travellers to high-risk areas. 
• It is scheduled in 3 doses, that is, days 0, 7, and 21 or 28. 
• A booster shot may also be suggested for people at higher risk of rabies. 

Post-exposure Prophylaxis (PEP)

Post-exposure prophylaxis is the emergency response, given only after exposure to or potential risk of the virus: 

• This helps to prevent the entry of the virus into the central nervous system.  
• Cleaning of the wound with soap and running water is necessary before giving the vaccine. 
• 4 to 5 doses of rabies vaccine are given over a 14 to 28 day span. 

Other Preventive Measures 

• Vaccinating the source of transmission, the rabid animals, mostly dogs, is the best measure for preventing this disease in terms of cost as well as effectiveness. 
• Educating people about this deadly yet preventable disease can make a huge difference, as well.  
• Taking shots for the rabies vaccine is also an effective way to prevent the spread of rabies within the body. 

6.0Rabies Treatment: Is There a Cure?

Rabies can not be treated even with advanced medical procedures. The only possible way to stay safe from this disease is to prevent it with the preventive measures discussed above. Apart from this, supportive care is also used for a very few individuals, but this approach remains controversial due to the use of aggressive experimental treatments. The lack of a proper treatment option for this disease is even more daunting to humankind to this day, with the only option for survival being a rabies vaccine.