What Is Furious Rabies

Furious rabies is an infectious disease caused by one of the deadliest viruses known to humans, the rabies virus (RABV). The infection is transmitted by the bite of a rabid animal, and once signs and symptoms appear, the patient will die within days in >99.9% of the time. Although there is no cure for rabies, it can be prevented by vaccinating dogs and people who are bitten by a rabid animal immediately following exposure. In this article, you will learn more about this deadly infectious disease, how it is transmitted, its signs and symptoms, diagnosis, treatment, and prevention.

Furious rabies:

Rabies is a viral infectious disease caused by a virus called the rabies virus (RABV), and it claims the lives of >60,000 people each year. The virus attacks the central nervous system (CNS) and once it reaches the brain and the signs and symptoms appear, it is ~100% lethal.¹ This infectious disease is spread in countries where there is poor access to healthcare systems and where dogs are not widely vaccinated, specifically in countries in Asia and Africa where >95% of death cases occur.¹

All warm-blooded animals (e.g. dogs, cats, bats, raccoons, etc.) can potentially cause rabies, but rabid dogs are responsible for 99% of rabies cases. The virus is transmitted by the bite or scratch of an infected animal, which will expose the muscle tissues to the animal’s saliva that contains the virus, the virus then travels to the neurons (nerve cells) and spreads in the CNS, and from the CNS the virus can spread to other parts of the body such as the tongue, salivary glands, skin, and heart.²

There are two variations of the illness that manifest in humans: the classical encephalitic (causing inflammation in the brain) or furious rabies and paralytic (dumb) rabies. Furious rabies is the most common type seen in around 80% of infected people.³ 

Signs and symptoms:

In humans, the incubation period (the time between being infected and the appearance of signs and symptoms) ranges between two weeks to several months (averages of 2-3 months).

Earlier signs can be:

• Fever
• Pain and itching at  the site of the bite

Characteristics signs of furious rabies then appear:

• Hydrophobia (fear of water): this manifests as extreme fear provoked when the patient attempts to drink water, or even at the mention, sight, or sound of water, accompanied by inspiratory muscle spasms
• Phases of aggressive behaviour, fear, and hallucinations
• Hypersalivation
• Sweating
• Fluctuating blood pressure

Complications:

• Cardiac disorders (diseases of the heart) such as low blood pressure and heart failure
• Respiratory disorders such as asphyxiation (lack of oxygen in the body) and pneumonia (infection in the lungs)
• Neurological disorders such as convulsions (uncontrollable, rapid shaking) and cerebral oedema (swelling of the brain)
• Coma ⁴

Prognosis:

Once the signs and symptoms appear, the illness is almost 100% lethal; while a patient with furious rabies dies within days, a patient with paralytic rabies can survive for several weeks. A patient rarely survives following the appearance of signs and symptoms, and in most reported cases of survivors, the patient had received at least one dose of the vaccine either before or following the encounter with the rapid animal.⁴ 

Diagnosis:

Clinical signs of illness are not enough to confirm furious rabies; for that purpose, the virus must be detected using a variety of laboratory tests:

• Detection of antigens: skin biopsies can be used to detect parts of the virus called antigens, using antibodies (proteins that our body makes against antigens) with special microscopes.
• Polymerase Chain Reaction (PCR): saliva samples can be used in a specific type of PCR test to detect the genetic material of the virus.
• Serological Tests: these are blood tests that detect the specific antibodies the immune system makes to fight off the virus. However, as these antibodies normally appear in the blood following the onset of signs and symptoms, they are mainly used to see if the immune system is responding to the vaccine.
• Detecting the virus in the brain tissue is the most common way of diagnosing rabies post-mortem (after death). (The World Health Organisation (WHO))

Treatment:

Post-exposure treatment:

This type of treatment is given to patients after they are exposed to (bitten by) a rabid animal. In this case, either a vaccine or immunoglobulins (antibodies against the virus) are given immediately following the bite.

 Before any treatment is given, your doctor might ask you for this information:

1. Date of exposure to the bite
2. Animal species (e.g. dog, bat, racoon, etc.) and their health status after the bite
3. Where did the bite occur (in a different country for example)
4. In which part of your body you were bitten
5. Whether you have allergies or immune problems
6. If you have received any type of rabies vaccination in the past
7. Your weight (NHS)

 Following assessment, the healthcare provider will decide if rabies is a possibility and will initiate treatment promptly. Rabies management consists of administering the rabies vaccine, either 4 doses over 21 days or two doses over 7 days. Vaccination could be coupled with giving human rabies immune globulin (HRIG), that is, antibodies against the virus that can help your body fight the virus immediately until your immune system starts making its own antibodies in response to the vaccine (UK Health Security Agency).

The first dose of vaccine should ideally be given during the first 24 hours of the bite, and the vaccine can prevent death in most cases (~99% of cases) if given as early as possible following the encounter with the rapid animal.¹ 

Rabies prevention:

Although rabies has no cure once signs and symptoms appear, it is a preventable infection.

Rabies in humans can be prevented by:

Pre-exposure immunisation is taking a vaccine to protect you in case you are bitten. This is different from post-exposure immunisation, which is taking the vaccine after the bite occurs. In the UK, there is a licensed vaccine called Rabipur® that contains parts of the inactivated virus. This vaccine is recommended in these cases:

• Laboratory staff that work with rabies virus
• Vets and their technical staff
• Animal control and wildlife workers
• People who are travelling abroad to high-risk countries

The vaccine is normally taken as an injection in the upper arm in three doses over a period of seven days. (UK Health Security Agency)

Rabies in animals can be prevented by:

• Regular visits to the veterinarian
• Keeping rabies vaccination up to date
• Keep your pets indoors or under strict  supervision
• Spay or neuter your pets to minimise the number of unwanted animals that might not be taken care of or vaccinated
• Limit your pet's interaction with wildlife (CDC)

FAQs:

Is there rabies in the UK?

The UK’s terrestrial animals (animals that mainly live on land, such as cats, dogs, etc.) have been rabies-free since the 1920s. However, in 2018, related viruses called European Bat Lyssavirus 1 and European Bat Lyssavirus 2 - which can cause rabies - appeared in bats. Therefore, any person who is scratched or bitten by a bat in the UK must contact a healthcare professional immediately, so their case is assessed, and treatment is initiated if necessary (UK Health Security Agency).

Should I seek medical help if I was bitten by a bat but have received pre-exposure rabies vaccination before?

Even in this case, the case must be evaluated, and post-exposure treatment started if needed. (NHS)

What precautions should I take if I travel abroad?

You will be advised to have pre-exposure immunisation before leaving the country.⁴ In addition, if you are travelling with your pet outside the UK, it is mandatory to vaccinate your pet. To view a list of countries based on their rabies risk, you can visit HERE.

How do I know if my pet has rabies?

Signs and symptoms might include:

• Sudden behaviour change: your pet might become extremely friendly and seek attention or aggressive and scared.
• Muscle weakness and droopy face
• Excessive drooling
• Difficulty walking

If you notice any odd, new behaviour from your animal, especially if you have been abroad, you should contact your vet.

Summary

Furious rabies is the most common type of rabies, a viral infectious disease caused by a bite or scratch of a rabid animal. Although many animals can transmit the disease, rabid dogs are responsible for most cases. Following an incubation period that can last several months, the signs and symptoms appear, and once this happens, the patient will die within several days. Although there is no cure for the disease, it can be prevented by vaccinating dogs against it, and by receiving the vaccine immediately after being bit by a rabid animal.