Rabies is a viral disease that is almost always fatal once symptoms appear. It is spread through the bite or scratch of an infected animal, most commonly dogs. Rabies has one of the highest case fatality rates of any disease. However, a small number of people have survived rabies without receiving the post-exposure prophylaxis (PEP) rabies vaccine.
Quick Facts on Rabies
- Rabies kills around 59,000 people worldwide each year
- Over 95% of rabies deaths occur in Africa and Asia
- Rabies has a case fatality rate of nearly 100% once symptoms appear
- Rabies can only infect mammals, with domestic dogs causing 99% of transmissions to humans
- Rabies is preventable through prompt post-bite vaccination and administration of immunoglobulin
Rabies Pre-Exposure and Post-Exposure Prophylaxis
There are two main approaches to rabies prevention:
Pre-exposure prophylaxis (PrEP) involves receiving a course of the rabies vaccine prior to any exposure. This primes the immune system and provides some protection. PrEP is recommended for people at high risk of exposure like veterinarians, animal handlers, and laboratory workers.
Post-exposure prophylaxis (PEP) involves promptly administering a course of the vaccine and rabies immunoglobulin after a potential rabies exposure, like a dog or bat bite. This prevents the virus from infecting the nervous system. PEP is highly effective at preventing rabies if given in a timely manner.
Rabies Case Fatality Rate
Once clinical symptoms of rabies appear, the case fatality rate is almost 100%. According to the WHO, rabies resulted in 61,000 human deaths worldwide in 2010. With only extremely rare exceptions, rabies is fatal unless appropriate PEP is administered before onset of symptoms.
This is because by the time symptoms appear, the rabies virus has already spread through peripheral nerves to infect the central nervous system and brain. At this stage, damage is irreversible and almost always fatal within days of symptom onset.
Rabies Survival Cases
Throughout history, there have been very few fully documented cases of human rabies survivors who did not receive any PEP or rabies vaccine after exposure:
- In 2004, 15-year-old Jeanna Giese of Wisconsin survived after contracting rabies from a bat bite
- In 2006, precautions were taken with an unvaccinated Brazilian boy who survived rabies after a bat bite
- In 2008, a Texas teenager survived rabies after being bitten by a bat
- In 2009, a 17-year-old Peruvian girl survived rabies after being bitten by a dog
- In 2011, an 8-year-old California girl survived rabies after being scratched by an infected cat
- In 2015, a 6-year-old Malawian boy survived rabies after being bitten by a dog
With extensive medical support, these patients received therapeutic comas and antiviral drugs. However, most subsequent attempts to replicate these survival cases have been unsuccessful.
Milwaukee Protocol for Rabies Treatment
The Milwaukee protocol is an experimental treatment approach that was first used in 2004 on Jeanna Giese, the Wisconsin rabies survivor. It involves:
- Inducing coma and intubation
- Administering antiviral medication
- Treating symptoms as they appear
- Gradually weaning the patient off sedation
The aim is to allow time for the immune system to mount an antibody response while the viral progression is slowed through induced coma and antivirals. However, there is limited evidence on its efficacy and most patients treated with the Milwaukee protocol still succumb to rabies.
How These Survivors Recovered from Rabies
The exact mechanisms behind rabies virus survival are not fully understood. However, some factors thought to play a role include:
- Prompt and intensive medical therapy – Therapeutic comas may protect the brain while antivirals inhibit the infection
- Variation in rabies virus strains – Some strains appear to be less lethal
- Immune response – In rare cases, the immune system may mount an early enough neutralizing antibody response
- Reduced viral load from limited exposure – Bites in highly innervated body parts like the face can transmit higher viral loads
- Young age – Younger patients may have greater neuroplasticity and immune system robustness
However, most rabies exposures still lead to fatal outcomes even with the Milwaukee approach. Survivors are extremely rare exceptions to the norm.
Number of Rabies Survivors Documented
Considering rabies has a nearly 100% fatality rate once symptoms manifest, the number of documented survivors worldwide is extremely low.
The exact global number of rabies survivors without preventive vaccination is unknown. However, when compiled across case reports, the total number appears to be under 30 cases since the early 20th century.
With tens of thousands of rabies deaths annually, the proportion of unvaccinated survivors is minuscule, with just a handful of isolated cases over the past 100 years. Almost all survivors were young children or teenagers.
Can Rabies Be Survived Without Vaccine?
Surviving rabies without getting the rabies vaccine or PEP after a potential exposure is extremely unlikely but not completely impossible in rare cases. A few factors that may improve chances include:
- Being bitten on a limb instead of near the head or neck
- Promptly cleansing the wound and applying antiviral medications
- Administering therapeutic coma and supportive medical care
- Being previously immunized against rabies before the exposure
- Receiving a lower viral load from limited exposure
However, the odds are still overwhelmingly against survival as the rabies virus is highly lethal. Receiving fast medical attention and proper post-exposure rabies vaccination as recommended remain the only reliable means of preventing rabies after a bite or exposure. Assuming rabies recovery without vaccine is risky and will almost certainly end in fatality.
How Effective is the Rabies Vaccine?
Modern cell-based rabies vaccines are extremely effective at preventing rabies when administered correctly. The rabies vaccine works by inducing antibody production against the rabies virus before infection reaches the central nervous system.
Some key statistics on rabies vaccine efficacy:
- More than 99% effective when given promptly and properly after exposure
- Provides full immunity within 7-10 days after receiving complete PEP regimen
- Immunity lasts a minimum of 2 years with some vaccines protecting for over 8 years
- Reduces rabies deaths by approximately 90% in high-risk populations and areas
As long as the vaccine is administered following guidelines before onset of rabies symptoms, it is nearly 100% effective at preventing progression to fatal disease. However, delaying vaccination even by a few days can severely reduce or eliminate its protective effects.
Rabies Virus Pathophysiology
Here is a brief overview of how the rabies virus causes disease and death after exposure:
- Exposure – Rabies is transmitted through infected saliva during a bite wound or contact with mucous membranes
- Incubation – The virus replicates at wound site and travels to peripheral nerves, taking 2-12 weeks before symptoms start
- Central nervous system infection – Virus spreads along neurons and infects the brain and spinal cord
- Neurologic symptoms – Fever, headache, anxiety and hallucinations begin as rabies impairs brain function
- Hydrophobia and death – Painful involuntary spasms occur on swallowing leading to fear of water, followed by death within days
Once the rabies virus enters the central nervous system and starts causing neurologic symptoms, survival becomes extremely unlikely. That is why rapid vaccination is key before the virus travels too far through nerve pathways.
Rabies Prevalence Around the World
While rabies does not have high prevalence in most developed countries, it remains endemic to many regions of the world, especially in Asia and Africa. Some key statistics according to the WHO:
- Over 95% of rabies deaths occur in Africa and Asia
- India has the highest rate of rabies globally, with about 36% of deaths
- China and India combined account for approximately 60% of global rabies deaths
- Up to 60% of rabies deaths are in children under 15 years old
- Rabies causes over 17,000 deaths annually in Africa, mostly in rural areas
Israel, Japan, New Zealand and most Western European nations have eliminated rabies. However, the disease still causes tens of thousands of preventable deaths across less developed regions each year.
Reducing Rabies Deaths Globally
Major global efforts are underway to reduce rabies deaths through coordinated strategies like:
- Mass vaccination of dogs and animals
- Improved access to human rabies vaccines and immunoglobulin
- Education on prompt post-bite medical care
- Enhanced rabies surveillance and diagnostics
- Training health workers in case management
With concerted international collaboration, the WHO target is to eliminate all human deaths from canine-mediated rabies by 2030. Key to success is increasing rabies prevention in dogs and availability of life-saving PEP across at-risk areas.
Conclusion
Rabies remains an almost universally fatal infectious disease once symptom onset occurs. However, post-exposure vaccination is nearly 100% effective at preventing rabies as long as administered promptly after viral exposure and according to protocol.
Although a handful of documented cases exist of rabies survival without vaccine, this represents merely a tiny fraction of rabies deaths globally. Rapidly receiving rabies PEP with vaccine is the only recommended way to prevent rabies after potential exposure. Global vaccination initiatives provide hope that human rabies fatalities can be eliminated in the coming decades.
