What is Rabies?
Rabies is a viral disease that is well-known for its negative neurological impacts and being entirely fatal to humans. It has been afflicting humans for thousands of years, with the earliest record cases being described in stone tablets from ancient Mesopotamian civilizations approximately 4000 years ago.[1] Fortunately, there have been significant breakthroughs in the treatment and prevention of this disease over the past two centuries, with the development of the rabies vaccine being among the most pivotal.
Transmission
The rabies virus is the microbe responsible for causing rabies disease and impacts only mammals, such as humans, cats, dogs, bats, and livestock, among other wild mammals. [2,3] Typically, the virus is spread between an infected animal via its spit getting into contact with broken skin or direct contact with mucosa tissues, such as the eyes or mouth. The most common way a human or animal gets exposed to rabies is by being bitten or scratched by an infected animal. [2,3]
A number of animals are known to transmit the disease to humans, with included animals being: dogs, bats, foxes, raccoons, skunks, and some other wild mammals. Dogs have historically been the most common animal that transmits rabies to humans, a trend that is still prevalent in many parts of the world. In countries such as the United States where there are large efforts to prevent rabies in dogs, bats tend to be the most common animal that transmits the disease to humans. [3]
Phases & Symptoms
Rabies goes through multiple stages as the disease progresses, from the initial bite through the virus traveling through the nervous system to eventually reaching the brain. The phases are:
Incubation: During this period, the virus is making its way from its entry point, such as a bite or scratch, to the body’s nervous system. This phase varies in length from days to several weeks, and no symptoms are experienced during this phase. If treatment is received at this point, no disease develops. [2,3]
Prodromal Phase: The rabies virus successfully entering the nervous system signifies the start of this phase and can last anywhere from 2 to 10 days. During this period, the virus begins to move through the body’s nerve network, slowly making its way to the central nervous system. Nerve damage also occurs during this stage and the onset of observable symptoms begins. Any treatment received during and after this phase is typically ineffective. [3]
Acute Neurologic Phase: Once rabies reaches the central nervous system, the disease progresses to the acute neurologic phase. This phase is associated with damage to the brain and spinal cord. Rabies has two forms at this point, each associated with different symptoms, being furious rabies and paralytic rabies. Furious rabies is the more common form, impacting approximately 2 in every 3 rabies patients. [3]
Coma & Death: Late-stage rabies infections often cause patients to drift into a coma, where death follows not long after. [3]
Symptoms develop in the prodromal phase, with fever, pain, and other flu-like symptoms being common. Numbness, tingling, or other odd sensations near the wound also start. [2,3] As the disease progresses to the acute neurologic phase, symptoms will differ depending on what form of rabies a patient has.
Furious rabies: This form of rabies is more common and is what most people think of when discussing rabies. Common symptoms include aggression, trouble controlling motor abilities, fast heart rate, fast breathing, producing large amounts of spit, seizures, hallucinations, fear of water, and fear of air/drafts. This form is often followed quickly by death. [2,3]
Paralytic rabies: This is the lesser common form of rabies and is more “calm” than furious rabies. Symptoms include stiffness of the neck, weakness that spreads from the initial wound location, tingling or similar sensations, paralysis, and eventual coma. [2,3]
Treatment & Diagnosis
Presently, there is no reliable diagnostic method to identify if a patient has contracted rabies if there are no symptoms. Some doctors may run tests to see if the rabies virus can be detected, though this is not guaranteed to detect the virus and tests may need to be run multiple times to confirm rabies presence. Such tests include saliva tests, biopsy of the skin, cerebrospinal fluid tests, blood tests, and MRIs. [2,3,4] Healthcare professionals strongly encourage people to promptly seek treatment if they have been potentially exposed to rabies, such as in the case of being bitten by a wild animal.
It is important that treatment begin before symptoms develop, as once symptoms start showing, primary treatment options are ineffective for virtually everyone. In the situation where someone is bitten or injured by an animal likely afflicted with rabies, post-exposure prophylaxis (PEP) should occur. A PEP response involves: [2]
Thoroughly washing the bite or scratch with soap and water for at least 15 minutes.
The injection of a series of rabies shots.
The use of human rabies virus antibodies, if deemed necessary.
Prevention
Due to rabies's high lethality, the best way to evade the disease is to take preventative measures. One of the most important preventative actions you can take is simply being aware of what rabies is, how it’s transmitted, and what actions to take if you believe you’ve been exposed to it. [3] Individuals at high risk of being exposed to rabies, such as people who work closely with animals or those traveling to areas where rabies is common in dogs, can receive pre-exposure prophylaxis (PREP) treatment. PREP consists of a series of two shots that help the body’s immune system recognize and attack the rabies virus if you get exposed to it later. It is recommended that you still seek out treatment if you get injured by a likely rabid animal even if you have previously received PREP. Other forms of preventative action you can take to avoid rabies are ensuring pets, such as cats and dogs, are regularly vaccinated against rabies, that pets don’t wander off unsupervised, and you do not touch wild animals. [2,3]
References:
Tarantola A. Four Thousand Years of Concepts Relating to Rabies in Animals and Humans, Its Prevention and Its Cure. Trop Med Infect Dis. 2017;2(2):5. Published 2017 Mar 24. doi:10.3390/tropicalmed2020005
Rabies: Causes, symptoms, treatment & prevention. Cleveland Clinic. August 27, 2022. Accessed December 10, 2024. https://my.clevelandclinic.org/health/diseases/13848-rabies.
Rabies. World Health Organization. June 5, 2024. Accessed December 10, 2024. https://www.who.int/news-room/fact-sheets/detail/rabies.
Rabies. Mayo Clinic. November 2, 2021. Accessed December 10, 2024. https://www.mayoclinic.org/diseases-conditions/rabies/diagnosis-treatment/drc-20351826. Assessed and Endorsed by the MedReport Medical Review Board