Rabies

Causes Of Rabies

Rabies is caused by the rabies virus that usually gets transmitted from infected animals. The virus lives in the saliva, brain and spinal cord of the infected animal. Rabies can infect mammals such as dogs, cats, bats, monkeys, foxes, raccoons, skunks, jackals and mongooses. The most common cause of transmission in humans are dogs. 

Transmission

The salivary glands play a very important role in spreading the infection. When an infected animal bite, the virus is released through saliva into the person’s body. The infection can spread through: 

• Bite of an infected animal

• Scratches by claws of infected animal

• Exposure of the infected saliva to nose, eyes, mouth, or cut skin

Rabies virus can also be transmitted from human to human through transplantation of the cornea or other organ. Although this transmission is rare, it is possible. Therefore, the corneas and other organs of a person who died of rabies should not be used for transplantation.

Note: Rabies is not spread by petting or touching dried saliva, blood, urine, or feces of a rabid animal.

After entering into the bloodstream, the virus enters into the central nervous system. After establishing the infection in the brain, the virus travels down the nerves from the brain and multiplies in different organs causing several complications. 

Symptoms Of Rabies

Symptoms of rabies can be divided into the following stages: 

Stage 1 (Incubation): It is the period from exposure of virus to the onset of symptoms and differs from person to person. This time is generally 2 to 3 months but may range from 1 week to 1 year. It is dependent on factors such as site of entry of the virus and the viral load

Stage 2 (Prodrome): This stage consists of non-specific symptoms that mostly resemble the flu with several gastrointestinal symptoms:

• Fever

• Headache

• Malaise

• Decrease in appetite

• Pain, numbness, tingling, and itching at the wound site

Stage 3 (Neurological): In this stage, the virus reaches the central nervous system. It causes fatal inflammation of the brain and spinal cord which can be experienced as the following symptoms: 

• Anxiety

• Confusion

• Agitation

• Delirium

• Disturbed behavior

• Hallucinations

• Hydrophobia (fear of water) 

• Insomnia

• Muscle aches

• Weak arms and legs

• Difficulty in swallowing

• Aerophobia (fear of fresh air)

Stage 4 (Coma): This stage usually develops within ten days of stage 3. Patients may have consistent hydrophobia and can develop paralysis. 

Stage 5 (Death): The stage 4 can lead to death within 2 to 3 days without supportive care.

Types Of Rabies

Rabies can be divided into two types depending upon the symptoms. These are:

Encephalitic (furious) rabies

It is the most prevalent form of rabies and affects 85% of the population infected with the rabies virus. 

In this type, patients experience symptoms such as: 

• Hyperactivity

• Excitable behavior

• Hydrophobia(fear of water)

• Aerophobia(fear of flying)

• Tachycardia (increase in heart rate)

• Tachypnea (abnormal rapid breathing)

It can also be life threatening due to cardio-pulmonary arrest. 

Paralytic rabies

As the name suggests, it causes paralysis of muscles that usually starts at the site bitten by the animal. Almost 20% of cases of rabies are of the paralytic type. It may also result in coma and eventually death of the patient. 

This form is often misinterpreted as normal paralysis and Guillain-Barre syndrome due to the absence of classical symptoms of rabies which include hydrophobia. Patients may also feel:

• Ongoing fevers

• Weakness

• Bladder dysfunction

Classic form

This form of rabies is rare, generally associated with seizures and more profound motor and sensory symptoms.

Risk Factors For Rabies

Low knowledge levels regarding rabies

Rabies is highly prevalent in the areas where people are having low knowledge regarding rabies and dog bites. The cases are especially seen in rural areas where people are unaware about the measures taken to prevent and manage rabies. 

Exposure to unvaccinated dogs

Dogs are the main source of spreading rabies. Exposure to stray dogs or unvaccinated dogs can be a source of infection. 

Living in rabies endemic countries

People living in rabies endemic countries with a poor control on dogs and wildlife are more prone to rabies infection. 

Age

Children are at high risk of catching the virus as they are more prone to be attacked by animals. Most cases of rabies are seen in children who are bitten by dogs, especially on their arms and faces. 

Diagnosis Of Rabies

An immediate medical attention is essential, if anybody is suspected to be bitten or scratched by an animal as there is no direct way to recognise a rabid animal.

However, the diagnostic tests can confirm the infection but it usually takes time and the dependency on the results can delay the treatment process.  

Testing the animal

The animal that is caught biting or scratching is first tested for rabies. This testing may save a patient from unnecessary physical, psychological, and financial stress if the animal is not found to be rapid. 

The rabies is usually diagnosed by direct fluorescent antibody (DFA) test. The DFA test detects the rabies virus antigens in brain tissue of the euthanized (put to death humanely) animal.

Animals that are found to be healthy such as a vaccinated dog or cat are not usually tested and kept under observation for 10 days. After this period, a doctor usually decides what to do after discussing with the local health department. 

Testing in humans

Rabies can be confirmed by various tests that detect the whole virus, viral antigens, or nucleic acids in infected tissues. Some of the tests are discussed below:

Lumbar puncture

In this, a sample of cerebrospinal fluid is taken for detection of the virus. The sample is taken using a thin needle from the lower part of the lumbar spine. 

Nuchal skin biopsy

It is the most reliable method of detecting the rabies virus during the first week. In this, a sample is collected from the skin of the back of the neck. The virus is detected using immunofluorescent antibody staining under a microscope. 

Real time polymerase chain reaction (RT-PCR)

In this, the saliva is tested for the presence of rabies virus. The method amplifies the genetic material of the virus (RNA) for the ease of identification. The test usually has high sensitivity and is used as a confirmatory test for detection of rabies infection. 

Blood tests

These tests are not used often for detection of rabies virus as the virus specific antibodies take time to reflect in the blood. They are mainly used to check the efficacy of the rabies vaccines given to the patient. The most common antibody test used is virus neutralization test which can be performed in two ways: 

• Fluorescent antibody virus neutralization FAVN) test

• Rapid fluorescent focus inhibition (RFFIT) test

Imaging tests

These tests are usually done to diagnose rabies encephalitis. The tests include:

• Magnetic resonance imaging (MRI) of head: This imaging technique uses magnetic fields and radio waves to create detailed pictures of the brain.

• Computed tomography (CT) scan of head: In this, X-rays are used to create detailed pictures of the head.. 

Specialist To Visit 

Rabies is a medical emergency as it can lead to fatal consequences in the absence of timely treatment. Any bite or scratch of an unfamiliar or wild  animal should not be ignored. Patients should wash the wounds immediately with soap and water and consult the doctor  for the assessment of the risk of rabies. 

Doctors usually decide the course of treatment after checking the wound developed due to an animal attack. The following doctor can help in the diagnosis and treatment of rabies: 

• General physician

• Infectious disease specialist

• Neurologist

• Neurosurgeon

If you are noticing any of the symptoms, seek advice from our world-class medical professionals.
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Prevention Of Rabies

Eliminating rabies in animals 

Rabies is a vaccine-preventable disease. It is important to keep the vaccinations of your dogs, cats, ferrets, and selected livestock up-to-date. A booster vaccination is also recommended in case your dog and cat is attacked or bitten by a wild animal.

Vaccination 

The same vaccine that is used in animals is also used to immunize people after an exposure. In some cases, vaccination is also required in humans before exposure to rabies. 

The vaccines for rabies have been available for more than 125 years. Earlier nerve tissue vaccines were used which have now been replaced with various modern cell culture and embryonated egg-based vaccines (CCEEVs). CCEEVs are more effective than earlier vaccines and have lesser side effects. 

Vaccinations of high risk people (Pre-exposure vaccination)

Vaccination is also recommended for the people who are at high risk of getting the disease. These include: 

• Veterinarian or an animal handler

• Veterinary student

• People who study or explore animals 

• Students working on rabies virus

• People traveling to the rabies prevalent countries

Vaccination is also recommended for children and infants living in an area with a high incidence of rabies and where the supply of immunoglobulin is limited. The vaccine can be given in 2 schedules, either via  intramuscular route or va intradermally at days 0, 7, and 21 and 28.

The booster doses are required only in some cases where there is a continuous exposure of the rabies virus. In case of exposure to rabies virus to vaccinated people, still post-prophylaxis is required. 

Vaccination after an animal bite

The vaccination is required if a person is bitten by a rabid animal. In this case, a doctor usually decides if you need the rabies vaccine. The vaccine is given in 4 doses, if you have not previously been vaccinated for rabies. The first dose is given immediately after the bite, followed by additional 3 doses which are given after 3 days, 1 week, and 2 weeks after the first dose. 

The person who has already received the rabies vaccine, requires only 2 doses. The first dose is given immediately after the bite and the second dose is given after 3 days. 

Vaccines lower the immunity for a period of time. So, it is necessary to tell your doctor if:

• Had an allergic reaction to the rabies vaccine in the past

• Have severe other allergies

• Have HIV infection

• Have cancer

• Are on some medications that can affect your immune system

• Are pregnant or breastfeeding

But in case, if it is confirmed that you are bitten by a rabid animal, you need to get vaccinated even in the presence of these conditions. 

Side effects of vaccination
The side effects of rabies vaccines are very mild and usually go away on their own. The common side effects include:

• Pain, swelling, and redness at the injection site

• Headache

• Upset stomach

• Pain in the stomach

• Muscle aches

• Dizziness

Some of the rare side effects include:

• Itchy spots on the skin

• Joint pain

• Fever

Avoiding animal exposure

The best protection against rabies is to avoid any wild animal that can transmit rabies. The following measures should be taken to avoid the exposure:

• Do not touch injured animals. In case you find an injured animal, contact the local authorities immediately for assistance.

• Do not feed, play or pat unknown animals, especially in areas where rabies is known to occur.

• Do not touch stray dogs and cats while traveling.

• Do not allow your pets to roam free as they may be infected by other animals. 

• Do not leave garbage or pet food outside. It may attract wild or stray animals.

• Do not keep wild animals as pets. 

• Do not ignore the strange behavior of your pet. Any change in behavior of the pet should be immediately reported to the veterinarian.

• Do not allow kids to touch or feed stray cats and dogs that may be wandering around them. Educate and remind kids to stay away from stray animals. 

Awareness on rabies

It is very important to understand the risk of rabies. Rabies is a fatal disease which is transmitted through animals, especially dogs. But, rabies in humans can be prevented through prompt vaccination and appropriate medical care. If you are bitten or scratched by an animal, immediately inform your doctor. 

Educating both children and adults about rabies and its prevention plays a very important role in limiting the exposure. Increasing awareness of rabies prevention and control in communities includes education and information on responsible pet ownership, how to prevent dog bites, and immediate care measures after a bite. 

Treatment Of Rabies

What to do after a bite or scratch by an animal, particularly a dog?

• Wash the wounds with soap and water, immediately as it will reduce the chances of infection.

• Flush the wound thoroughly for about 15 minutes with water.   

• Give first aid to the wound that includes applying an iodine-containing or anti-viral medication 

• Capture the animal in a large box, or atleast identify it, if possible. Do not risk further injury to yourself. 

• Call your family doctor immediately and explain to him/her about the bite.

• Call the Department of Health and animal control officer and provide them the accurate description of the animal.

• Avoid covering the wound with dressings or bandages. 

• Keep the biting animal under observation for 10 days. 

What to do if your pet is bitten or scratched by another animal, particularly a dog?

• Wear rubber gloves while washing your pet’s wounds.

• Call your pet’s veterinarian immediately.

Post-exposure prophylaxis (PEP)

There is no specific treatment for rabies, if symptoms start to develop. Therefore, the focus is given on preventing the exposure.  Even if rabies is not confirmed, treatment should start straight away. This is called post-exposure prophylaxis (PEP) and is done to prevent the infection. PEP refers to the prompt treatment of a bite that might expose the person to rabies. This helps in preventing the entry of viruses into the brain and consists of: 

• Extensive wound washing: It includes immediate washing of the wound with water, soap, detergent and povidone iodine for at least 15 minutes. This may help in removing or killing the virus. 

• Administration of rabies immune globulin: This gives immediate protection before the vaccine starts to work.

• Administration of rabies vaccine: The vaccine is injected immediately after a bite. It is given in 4 doses at 0,3rd, 7th, and 14th day of the bite. An extra dose at day 28 is also given to the patient with a weak immune system.

Home-care For Rabies

Rabies is a serious disease that involves the nervous system. Most of the patients are admitted to hospitals for the treatment. The caregivers or the family plays a very important role in maintaining the overall health of the patient. The following measures can be taken by the people that are taking care of the person.  

• Keep the patient calm, comfortable, and free from emotional upset

• Avoid contamination from saliva and broken skin of the patient by taking special precautions

• Keep the patient in a quiet room

• Keep the patient away from triggers (loud noise, intense light, and cold air) of muscle spasms and convulsions

• Allow the patient to take proper sleep to control excitability

• Keep the patient hydrated. 

Complications Of Rabies

The rabies virus travels through the peripheral nervous system and targets the central nervous system (brain) which can cause neurological complications such as encephalomyelitis. This can also cause anxiety, agitation and delirium. The virus can travel back to the PNS and can attack various peripheral organs such as salivary glands. 

The virus can cause the complete failure of the entire nervous system which can even cause death of the infected person. All these changes can develop following complications in patients.

• Seizures

• Fasciculations

• Psychosis

• Aphasia

• Autonomic instability

• Paralysis

• Coma

• Cardiopulmonary disorders

• Multiple organ failure

• Cardiac arrest

• Hypotension

• Confusion

• Paralysis of lower legs

• Problems swallowing due to painful throat and voice box spasms

• Insomnia

• Apnea

• Death