Rabies

Rabies kills nearly tens of thousands of people worldwide each year, yet many remain unaware of its serious nature until it's too late. This deadly virus attacks the nervous system and becomes fatal once symptoms appear. This comprehensive guide explains everything about rabies infection, including its causes, symptoms, and various rabies prevention and treatment approaches.

What is Rabies?

Rabies is a serious viral disease that attacks the central nervous system (CNS), affecting humans and animals. Rabies disease is caused by the rabies virus (RABV), primarily transmitted through the bite or saliva of infected animals, typically entering the body through bites, scratches, or contact with open wounds.

The vaccine-preventable condition presents itself in two distinct forms: 

• Furious rabies, the more common rabies type, causes hyperactivity, excitable behaviour, and distinctive symptoms like fear of water (hydrophobia) and fear of fresh air (aerophobia). 
• Paralytic rabies, accounting for about 20% of human cases, progresses more slowly with gradual muscle paralysis.

Rabies Transmission

Rabies is transmitted by mammals that feed their offspring with milk. As a result, any mammal can transmit this disease. Domestic and wild animals are common sources of infection for humans.

Among pets and domesticated animals that can become carriers of rabies are cats, dogs, ferrets, cattle, goats, and horses. Wild animals that may cause the transmission of rabies are bats, raccoons, skunks, foxes, coyotes, beavers, monkeys, and woodchucks.

Very rarely has it occurred that rabies is transmitted through the transplant of tissues.

Symptoms of Rabies

The symptoms of rabies in humans typically develop in stages, with an incubation period that can range from a few days to over a year. However, most cases show signs within 1-12 weeks after exposure.

The initial phase begins with symptoms that might be mistaken for common illnesses. The early signs of rabies in humans include:

• Fever and headache
• Muscle aches and fatigue
• Loss of appetite
• Tingling or itching at the bite site
• A general feeling of unwellness

As the virus progresses to the central nervous system, it manifests in two distinct forms. Furious rabies, the more common type, causes:

• Aggressive behaviour
• Agitation and restlessness
• Hallucinations
• Excessive salivation
• Fear of water (hydrophobia)
• Fear of drafts (aerophobia)
• Seizures and muscle spasms
• Muscle twitching (fasciculations)

Paralytic rabies, accounting for approximately 20% of cases, presents differently. This form progresses more slowly, with muscles gradually becoming paralysed, starting from the wound site. Rabies symptoms in humans may include weakness, tingling sensations, neck stiffness, and eventual coma development.

Causes of Rabies

The rabies virus (RABV) primarily spreads through the saliva of infected animals, typically entering the body through bites or when infected saliva comes into contact with open wounds or mucous membranes. While dogs are responsible for 99% of human rabies cases globally, the risk landscape varies by region, with other animals like bats, raccoons, or foxes playing a significant role in some areas.

Several factors can increase an individual's risk of rabies exposure. Commonly, rabies is caused by

• Living or travelling in developing countries where rabies is more common
• Activities involving contact with wild animals, such as cave exploration
• Occupational exposure, particularly veterinarians and laboratory workers
• Wounds to the head or neck which can accelerate virus progression to the brain

Complications of Rabies

Furious rabies leads to severe neurological complications, including:

• Uncontrollable hyperactivity
• Frightening hallucinations
• Complete loss of coordination
• Intense fear of water (hydrophobia)
• Extreme fear of fresh air (aerophobia)
• Various heart rhythm abnormalities and potential heart failure
• Breathing difficulties, oxygen deficiency, and pneumonia

Paralytic rabies progresses more slowly, with muscles gradually becoming paralysed from the infection site before leading to coma development.

Rabies Risk Factors

The possibility of infection rises when there is a higher risk of exposure to infected animals or an environment where the rabies virus is prevalent. The important risk factors of rabies include:

• Bites and scratches by animals: These are most likely by dogs, bats, raccoons, foxes, and any wild animals in areas where rabies exists.
• Working or living in areas of high risk: Areas such as parts of Asia and Africa, and rural places where vaccination programs for animals are not common.
• Unvaccinating pets: Having unvaccinated pets, such as dogs or cats, will increase the risk of infection.
• Occupational risks: Veterinary, animal handling, wildlife management, and laboratory workers are at higher risk due to their contact with animals.
• Handling or feeding wild animals: This increases the chances of exposure.
• Poor access to medical facilities: Lack of medical attention in case of exposure to the infection causes an increased risk.
• Bat contact: Exposure to bats, either residing in your house or in the surroundings, is an important risk factor.

Diagnosis

Diagnosing rabies presents unique challenges, as no single test can confirm the infection before symptoms appear. Doctors must conduct multiple tests on various samples to reach a definitive diagnosis.

• Direct Fluorescent Antibody (DFA): The DFA test serves as the gold standard for rabies diagnosis, offering accurate results within 1-2 hours. This test examines brain tissue samples using specialised fluorescent microscopy techniques to detect the presence of rabies virus antigens.
• Additional Testing:
  • Saliva analysis
  • Spinal fluid examination
  • Skin biopsies from neck hair follicles
  • Serum testing
• LN34 PCR Test: A newer diagnostic tool, this test uses real-time reverse transcriptase technology to detect viral genetic material. This innovative method proves particularly useful for testing decomposed or preserved tissues that might not be suitable for other diagnostic techniques.

Rabies Treatment

The primary approach is Post-exposure Prophylaxis (PEP), which must be administered as quickly as possible after potential exposure.

The PEP protocol consists of several crucial components:

• Immediate and thorough wound cleaning with soap and water
• Administration of human rabies immune globulin (HRIG)
• A course of rabies vaccines over 14 days

For individuals who have never received rabies vaccination before, the treatment includes both HRIG and four doses of rabies vaccine administered over two weeks. The HRIG provides immediate protection while the body develops its immune response to the vaccine.

Previously vaccinated individuals require a different protocol, consisting of only two vaccines given three days apart. They do not need HRIG as their bodies can mount a faster immune response due to previous vaccination.

The first dose of vaccine should be given as soon as possible after exposure, with subsequent doses following a strict schedule on days 3, 7, and 14. An additional fifth dose may be recommended on day 28 for people with compromised immune systems.

When to See a Doctor

Immediate emergency care is essential for severe bites, especially those near the head or neck, or exposures involving high-risk animals like bats, raccoons, skunks, or foxes. Even if someone isn't sure about being bitten, they should seek medical attention. 

Prevention

There are several methods you can consider to minimize your chances of coming into contact with rodent-like animals:

• Protect your small pets. Keeping rabbits, guinea pigs, and other small animals inside or in secure enclosures where they can't come into contact with wild animals will help prevent rabies. These small animals cannot be vaccinated against rabies and are at high risk for contracting the disease.
• Keep your pets in a safe environment. Always keep your pets indoors and supervise them when outside to avoid contact with wildlife.
• Vaccinate your pets against rabies. Vaccines for cats, dogs, and ferrets are available. Your vet can tell you how often your pets should receive vaccinations.
• Avoid contact with wild animals. Rabid (rodent) animals may display unusual behaviour; therefore, it is best to avoid handling a wild animal that appears to be friendly.
• If you plan to travel to an area where you may be exposed to animals that could carry rabies, consider getting vaccinated.
• Prevent bats from entering your house. Make sure all entry points for bats are sealed. If you have bats in your house, get the help of a professional to remove them and prevent them from coming back in.

Conclusion

Rabies remains one of the deadliest diseases known to medical science, yet proper understanding and quick action can prevent its fatal consequences. The disease kills nearly thousands of people annually, making prevention and awareness crucial tools in the fight against this virus.

Medical advances have made rabies preventable through proper vaccination and timely post-exposure treatment. People should wash any animal bite thoroughly with soap and lukewarm water, seek immediate medical care, and follow the prescribed vaccination schedule. These simple steps, combined with keeping pets vaccinated and avoiding contact with wild animals, can prevent most rabies cases.

FAQs

1. What happens when you get rabies?

The rabies virus travels slowly through nerve cells to reach the brain. Infected individuals show no symptoms during the incubation period, which typically lasts 2-3 months. Once the virus reaches the brain, it causes inflammation, leading to neurological symptoms if untreated.

2. How does rabies affect your body?

The virus primarily attacks the central nervous system, causing progressive damage. Effects include:

• Initial flu-like symptoms
• Nerve damage at the bite site
• Brain inflammation
• Behavioural changes
• Progressive paralysis

3. What animals are you most likely to get rabies from?

Globally, dogs are responsible for 99% of human rabies transmissions. Raccoons, bats, and foxes are the primary carriers in regions like the Americas. Raccoons remain the most frequently reported rabid animals, particularly in southeastern and northeastern areas. 

4. What happens if you get rabies?

Without rabies virus treatment, the virus causes fatal inflammation of the brain and spinal cord. The disease progresses through distinct phases, from early flu-like symptoms to either furious or paralytic rabies. Once symptoms appear, the condition is almost always fatal.

5. When to take the rabies vaccine?

Vaccination should begin immediately after potential exposure to the virus. The post-exposure treatment includes four doses over two weeks for previously unvaccinated individuals. For those previously vaccinated, only two doses are required.

6. Why can't rabies be cured?

The rabies virus becomes untreatable once it reaches the brain because the blood-brain barrier (BBB) protects it. This natural defence mechanism prevents medications from reaching the virus, making the disease fatal once symptoms appear.

7. What is the best treatment for rabies?

The best treatment for rabies is washing the bite area with water in addition to post-exposure prophylaxis, which is a rabies vaccine.

8. How long before symptoms show for rabies?

It usually takes one to three months for symptoms to appear after infection, though the time can be anywhere between two days and a year.

9. What are the first signs of a dog bite with rabies?

Some of the early signs include pain, numbness, or a tingling feeling at the site of the bite, followed by fever, headache, fatigue, and weakness.

10. What is silent rabies?

This rare type of rabies is referred to as paralytic rabies. It is a rare type of rabies that causes weakness and paralysis.

11. What are 5 symptoms of rabies?

Some of the common symptoms include fever, headache, pain, numbness, and difficulty swallowing.

Dr. Chaitanya Challa

MBBS, MD (Internal Medicine), PDCC (Critical Care), FCCS (Critical Care), Diploma in Endocrinology and Diabetes
CARE Hospitals Outpatient Centre, Banjara Hills, Hyderabad

To Book an Appointment, call:

+91 40-68106529

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