Yes, rabies is a disease that can and does affect humans. Rabies is caused by infection with the rabies virus, which is spread through contact with the saliva of an infected animal, most commonly through bites. Once a person develops symptoms, rabies is almost always fatal. However, rabies is preventable if treatment is administered soon after exposure, before the onset of symptoms.
What is rabies?
Rabies is an acute, viral disease that causes inflammation of the brain in humans and other mammals. It is caused by infection with rabies virus, a RNA virus in the family Rhabdoviridae, genus Lyssavirus.
The rabies virus is transmitted through contact with infected saliva, usually via bites or scratches from an infected animal. Less commonly, it can be contracted if infected saliva comes into contact with mucous membranes or broken skin.
Once the virus enters the body, it travels along nerves towards the brain in a process called “retrograde axonal transport.” As the virus reaches the brain and starts replicating there, it causes encephalitis, or inflammation and swelling of the brain and spinal cord. This leads to the various neurological symptoms associated with rabies.
Symptoms
After an incubation period that lasts a few days to several years, initial rabies symptoms appear that are similar to the flu. These include:
– Fever
– Headache
– Nausea
– Vomiting
– Agitation
As the disease progresses and the virus spreads through the central nervous system, more specific symptoms emerge:
– Anxiety
– Confusion
– Partial paralysis
– Hydrophobia (fear of water)
– Hyperactivity
– Difficulty swallowing
– Excess salivation
– Hallucinations
– Insomnia
Ultimately, the infection leads to seizures and complete paralysis as the virus overwhelms the nervous system. Death usually occurs within a few days after the onset of symptoms.
Transmission
The vast majority of rabies virus transmissions to humans occur through infected saliva penetrating the skin, usually via animal bites. Less commonly, exposure of open wounds or mucous membranes to saliva or other potentially infectious material, like neural tissue, may also transmit rabies.
In the Americas, wild animals are the primary source of infection, especially raccoons, skunks, bats, foxes and coyotes. Worldwide, most rabies deaths result from dog bites. In the developing world, improper or incomplete vaccination of dogs is a major factor in human rabies deaths.
Other mammals, both wild and domesticated, can also spread rabies to humans, including cattle and cats. Squirrels, rats, hamsters, guinea pigs, gerbils, chipmunks, rabbits, and hares are almost never found to be infected with rabies and have not been known to transmit rabies to humans.
History of Rabies
Rabies has been recognized as a disease for thousands of years and is one of the oldest documented infectious diseases affecting humans. References to rabies-like symptoms and hydrophobia appear in ancient texts from China, Greece, and Rome.
The earliest written record of rabies is in the Mesopotamian Codex of Eshnunna from around 1930 BC, which describes symptoms of hydrophobia in dogs. The first written report of rabies as a transmissible disease came from the Greek philosopher Democritus in 500 BC.
In the first century AD, the Roman encyclopedist Aulus Cornelius Celsus described the classic symptoms of fatal rabies after being bitten by a rabid dog. He recommended cauterizing the wound with a hot iron to prevent disease transmission, one of the earliest documented medical interventions.
Over the centuries, rabies continued to inspire fear for its grim prognosis. The disease became known by names referencing its most recognizable symptom, hydrophobia, including “lyssa” in Greek and “aqua-mentis” in Medieval Latin.
Major Events in Rabies History
– 1885 – Louis Pasteur successfully administered the first rabies vaccine to 9-year-old Joseph Meister after the boy was bitten by a rabid dog. This pioneering work opened the door for modern vaccination practices.
– 1903 – A competition led to the development of a rabies vaccine that could be administered after exposure, enabling life-saving post-exposure prophylaxis regimens.
– 1958 – The first human rabies death attributed to a bat bite occurred in the Americas, marking bats as an emerging vector.
– 1975 – Australia officially declared itself rabies-free, eliminating the virus from the continent through control measures.
– 2004 – A vaccine protocol called the Milwaukee protocol reported successfully treating the first case of human rabies without pre-exposure vaccination, though its true efficacy remains controversial.
– 2018 – Rabies deaths worldwide dropped below 100,000 annually for the first time, indicating progress in canine vaccination and public health efforts.
How Many Cases of Rabies in Humans Are There?
While no official global tally exists, the World Health Organization estimates rabies causes approximately 59,000 human deaths worldwide each year as of 2019 data. This has decreased substantially from estimates of over 200,000 annual rabies deaths in the 1990s.
Over 95% of rabies cases and deaths occur in Africa and Asia, concentrated in rural or impoverished regions. India has the highest rate of human rabies globally, accounting for approximately 36% of deaths.
China, Africa, southeast Asia and Latin America also report high rates:
| Region | Estimated Annual Rabies Deaths |
|---|---|
| Africa | 24,000 |
| Asia | 31,000 |
| Americas | 4,200 |
The number of rabies cases in the United States has dramatically declined due to animal control and vaccination programs. Currently, 1-3 rabies deaths are reported each year in the US.
Wild animals account for over 90% of reported rabies cases in the US. Bats are the most common source, representing about 30% of annual cases, followed by raccoons, skunks, and foxes.
Key Facts on Human Rabies Cases
– 99% of rabies cases occur in Africa and Asia.
– India has the highest rate of rabies globally.
– Rabies causes approximately 59,000 deaths annually worldwide.
– Rabies deaths have decreased by over 90% in the last three decades.
– Wild animals cause most rabies cases in developed countries.
– Rabies remains almost universally fatal once symptoms appear, though preventive treatment is highly effective.
Notable Rabies Cases in History
While thousands of anonymous cases have been lost to history, some individual stories of rabies stand out. Many early cases helped establish the disease’s traits and lethality in humans, while others illustrate the importance of modern prevention and treatment.
Earliest Recorded Case
– 2300 BC (approx.) – The Eshnunna Codex records a case of a man displaying rabies-like symptoms after being bitten by a dog in ancient Mesopotamia. This is the first identifiable description of rabies transmission.
Establishing Rabies as Transmissible
– 1st century AD – Aulus Cornelius Celsus recorded a case of a man developing fatal rabies after being bitten by a rabid dog and recommended cauterization to prevent disease transmission.
Rabies in the New World
– 1768 – A 6-year-old girl in Virginia died of the first documented case of rabies in the American colonies after she was attacked by a rabid dog.
Developing Treatments
– 1885 – Louis Pasteur successfully administered his new rabies vaccine to 9-year-old Joseph Meister after Meister was badly mauled by a rabid dog. The vaccine saved the boy’s life.
Wildlife Rabies Emerges
– 1958 – The first known human rabies case from a bat bite occurred in Texas. Bats were established as a wildlife rabies vector in the Americas.
Post-Exposure Prophylaxis Failures
– 2004 – A teenager in Wisconsin died of rabies despite receiving post-exposure treatment, a rare failure highlighting the need for prompt prophylaxis.
Experimental Treatment Failure
– 2021 – A teenager in Florida died of rabies despite being treated with the controversial Milwaukee protocol, reaffirming the protocol’s poor outcomes.
Has Rabies Ever Been Cured After Symptoms Started?
Once clinical signs of rabies appear, the disease has essentially a 100% fatality rate. Rabies progresses rapidly once the initial flu-like symptoms emerge, with death occurring within days due to multi-organ failure. Even intensive medical intervention and supportive care cannot stop this rapid deterioration.
For this reason, rabies treatment focuses on preventing the disease from developing after exposure rather than attempting to cure it.
Modern post-exposure prophylaxis (PEP) regimens, consisting of rabies immune globulin and vaccination, are nearly 100% effective if administered promptly after contact with rabies virus. However, there are no proven treatments that can halt or reverse rabies once symptoms set in.
The Milwaukee Protocol
In 2004, a 15-year-old girl named Jeanna Giese in Wisconsin became the first patient to survive rabies without pre-exposure vaccination. She underwent an experimental treatment regimen at the Children’s Hospital of Wisconsin that involved:
– Inducing a coma and administering antiviral drugs
– Providing intensive care life support
– Gradual weaning and rehabilitation over weeks
This approach was termed the Milwaukee protocol after the city where it originated, though its effectiveness is highly disputed.
Since 2004, the protocol has been utilized in over 35 rabies cases worldwide with a survival rate under 10%. Given the near-absolute lethality of symptomatic rabies, some consider even a single survivor a success. However, most experts argue the protocol has not demonstrated efficacy better than standard palliative care.
Key Takeaways
– Rabies remains 100% fatal once clinical symptoms manifest.
– No current treatments have conclusively halted or reversed rabies once symptoms appear.
– The controversial Milwaukee protocol has less than a 10% success rate.
– Modern vaccines and immunoglobulin prevent nearly 100% of rabies cases when given promptly after exposure.
What Is the Rabies Survival Rate?
The rabies survival rate after symptoms begin is essentially zero. Only 14 people have ever conclusively survived rabies after showing clinical signs, with most dying within days to weeks even with intensive care.
This near-absolute lethality makes rabies the deadliest infectious disease for those unvaccinated. However, the disease is also nearly 100% preventable when post-exposure prophylaxis is swiftly administered.
Rabies Survival Rate Data
– Survival rate after symptoms onset: Key Factors in Rabies Survival
The central factors that determine rabies survival are:
– Speed of post-exposure prophylaxis – The faster treatment begins after exposure, the higher the odds of survival. Over 99% survive if treated promptly.
– Vaccination status – Having prior pre-exposure vaccination leads to higher immune response and survival chances with post-exposure treatment.
– Intensive care – Palliative ICU support may slightly prolong survival once symptomatic but does not prevent death.
– Experimental treatment – No cure exists once symptomatic and experimental treatments like the Milwaukee protocol demonstrate little life-saving efficacy.
How is Rabies Transmitted from Animals to Humans?
Rabies is almost always transmitted from animals to humans through contact between infected saliva and broken skin or mucous membranes.
– The vast majority (80-90%) of rabies transmissions occur via animal bites.
– Saliva contacting open wounds or scratches may also transmit rabies.
– More rarely, rabies may spread through saliva contact with mucous membranes of the eyes, nose, or mouth.
Infected saliva contains live rabies virus particles that enter nerves at the site of contact and travel to the central nervous system. The virus spreads quickly along peripheral and central neurons, eventually overwhelming the brain and central nervous system.
Common Animal Sources of Human Rabies
While all mammals can contract rabies, certain animals are the most common sources of human rabies infections globally:
– Dogs – Responsible for the majority of annual human rabies deaths worldwide, particularly in developing nations. Most transmissions are from bites. Stray dogs are the greatest source.
– Bats – A frequent source in the Americas. Bats often transmit through scratches or unnoticed bites rather than severe mauling. May also transmit via accidental mucous contact in caves.
– Foxes – One of the most common wildlife vectors in Europe, Canada, and Alaska. Especially red foxes and Arctic foxes. Most transmissions occur via bites.
– Raccoons – The leading rabies vector in the eastern United States. Raccoon bites and scratches transmit the virus.
– Skunks – Frequent carriers in North America that spread rabies through bites primarily. Omnivorous and live near humans.
Key Facts on Rabies Transmission
– Rabies requires contact between infected saliva and human mucous membranes or broken skin.
– Bites cause the vast majority of rabies infections as they introduce virus-laden saliva deep into tissue.
– Globally, dogs are the main animal reservoir and transmitters of rabies to people.
– Wildlife like bats and foxes frequently spread rabies in regions where dog vaccination programs control canine rabies.
How Can Rabies Be Prevented?
Rigorous animal vaccination and control programs, public education, and prompt administration of post-exposure prophylaxis medications effectively prevent rabies transmission and provide over 99% protection after exposure.
Some key rabies prevention strategies include:
Animal Vaccination
– Mass vaccination of domestic dogs and cats
– Oral rabies vaccine bait drops for wildlife like foxes
– Trap-neuter-vaccinate-return programs for community pets
– Mandatory rabies vaccination laws for pets
Vaccinating domestic animals and wildlife prevents them from transmitting rabies and establishes immune barriers between vectors and humans.
Bite Prevention
– Educating children to avoid unknown animals and report bites
– Proper animal handling techniques
– Supervision of children around animals
– Restricting wildlife access to food sources
Simple education and responsible pet ownership practices reduce bite chances. Avoiding interactions with unfamiliar animals also lowers rabies risk.
Post-Exposure Prophylaxis
– Immediate washing of bite wounds with soap and water
– Swift administration of rabies immune globulin and vaccine after exposure
– Completion of full vaccine dose schedule for maximum immunity
The faster vaccines and antibodies are given after exposure, the higher the odds of preventing rabies virus from infecting the central nervous system.
Pre-Exposure Immunization
– Providing three-dose vaccine series to high-risk groups like veterinarians
– Immunizing travelers visiting areas with endemic dog rabies
– Maintaining routine childhood and booster shot immunization schedules
Pre-exposure vaccines prime the immune system to mount a faster response to post-exposure prophylaxis and may provide protection if post-exposure treatment is delayed.
Conclusion
Rabies is an ancient viral disease that has affected mankind for millennia. While human rabies cases are increasingly rare due to modern preventive measures, the disease remains almost universally fatal once neurological symptoms develop. However, starting prompt vaccination and immunoglobulin therapy after exposure almost always prevents the disease from manifesting and protects exposed individuals. Thanks to widespread animal vaccination initiatives and effective post-bite prophylactic regimens, rabies is well controlled in many regions, though it remains a threat where animal reservoirs are unmanaged. Vigilance in animal and human vaccination, bite prevention education, and rapid post-exposure treatment will continue driving down rabies cases and deaths worldwide.
