What is rabies?
Rabies is a viral disease caused by the rabies virus. The rabies virus infects the central nervous system and causes inflammation of the brain (encephalitis) in humans and other mammals. It is spread through the saliva of infected animals, most commonly through a bite. Rabies virus belongs to the Lyssavirus genus of the Rhabdoviridae family.
Once symptoms appear, rabies is almost always fatal. However, it is completely preventable if treatment is provided shortly after exposure. According to the Centers for Disease Control and Prevention (CDC), rabies causes approximately 59,000 deaths worldwide each year. More than 95% of human deaths from rabies occur in Africa and Asia.
The rabies virus has the ability to infect any mammal. In the United States, several wild animals serve as natural reservoirs for the disease including raccoons, skunks, bats, and foxes. Unvaccinated domestic animals like dogs, cats, horses, and cattle are also at risk for rabies infections from these wild reservoirs. The rabies virus is spread through the saliva of infected animals, most often via bites that break the skin.
Rabies has one of the highest case-fatality ratios of any infectious disease. Once the rabies virus reaches the central nervous system, brain inflammation (encephalitis) occurs along with other severe neurological symptoms. Death usually occurs within days after the onset of symptoms. There are only a handful of documented cases of human survivors after displaying symptoms. Once the symptoms of rabies appear, the disease is essentially 100% fatal.
According to the CDC, prompt administration of post-exposure prophylaxis (PEP) after suspected rabies exposure prevents the onset of rabies in virtually 100% of cases. However, there is no effective treatment once the symptoms of rabies begin. For this reason, rabies prevention through vaccination of pets and avoiding contact with wild animals is critical.
In summary, rabies is a fatal viral disease that infects the central nervous system. It is transmitted through animal saliva, most commonly from the bite of an infected animal. Once symptoms appear, rabies is essentially always fatal. However, it can be prevented through vaccination and prompt treatment after exposure.
Sources:
https://www.cdc.gov/rabies/about.html
https://www.who.int/news-room/fact-sheets/detail/rabies
How is rabies transmitted?
Rabies is spread through bites or scratches from an infected animal. The rabies virus is found in an infected animal’s saliva. If the saliva comes into contact with broken skin or mucous membranes (eyes, nose, mouth), the virus can enter the body and cause an infection.
According to the CDC, “Rabies virus is transmitted through direct contact (such as through broken skin or mucous membranes in the eyes, nose, or mouth) with saliva or neural tissue from an infected animal.”
The virus spreads when an infected animal bites or scratches another animal or person. The CDC states that rabies is mostly transmitted through “bite wounds or virus-laden saliva of rabid animals getting into open wounds or mucous membranes.”
An infected animal can only spread the virus after it starts shedding the virus in its saliva. However, rabies is not spread through blood, urine, or feces.
Human-to-human transmission through saliva contact has never been confirmed according to the WHO. Rabies is primarily spread to humans through infected domestic pets like dogs and cats.
Can you get rabies just from a dog’s saliva?
Yes, dog saliva can contain rabies virus if the dog is infected. According to the CDC, rabies virus is transmitted through the saliva of infected animals https://www.cdc.gov/rabies/transmission/index.html. Extensive studies show that rabies virus can be excreted in the saliva of dogs several days before illness starts https://www.cdc.gov/rabies/transmission/body.html.
However, contact with saliva alone is not enough for transmission. Rabies virus enters the body through broken skin or mucous membranes when an infected animal bites or scratches. Licks to exposed skin, eyes, mouth or nose could also transmit rabies, but the risk is very low. Simply petting or handling an infected dog and then touching your mouth, nose or eyes will not spread rabies.
In summary, while dog saliva can contain rabies virus, bites or scratches that break the skin are required for the virus to infect a person. Casual contact with saliva alone does not lead to rabies.
What are the stages of a rabies infection?
Rabies infection in humans progresses through several stages:
Incubation Period
After exposure to rabies, the virus travels from the wound site to the central nervous system, which marks the beginning of the incubation period. This normally takes 1-3 months but can range from <10 days to >1 year (1). The incubation period depends on factors like the location of the bite, viral load in the saliva, and proximity to the brain.
Early Symptoms
As the virus proliferates in the nervous system, early flu-like symptoms emerge which may last 2-10 days. These include fever, headache, weakness, discomfort, loss of appetite, nausea, and tingling at the site of the bite. There may also be behavioral changes like anxiety, agitation, and confusion (2).
Late Symptoms
In the late stage, neurological symptoms appear as the virus attacks the brain and spinal cord. These include hallucinations, delirium, abnormal behavior, hydrophobia (fear of water), and insomnia. Paralysis then sets in, usually starting at the site of the bite (3).
Coma and Death
The final stage is coma leading to death, usually by cardiorespiratory arrest. Without treatment, rabies has a near 100% fatality rate once clinical signs appear (4). The acute period of disease typically lasts 2-10 days (3).
How common is rabies transmission from dogs?
Dogs are the most common transmitter of rabies to humans worldwide. According to the CDC, up to 99% of rabies cases result from dog bites. While cases of human rabies in the U.S. are rare, with only 1 to 3 cases reported annually, the vast majority of these are caused by rabies infected dogs.
The World Health Organization (WHO) estimates that tens of thousands of people die every year from rabies transmitted by dogs. Most of these deaths occur in Africa and Asia, where large populations of stray dogs increase the risk of rabies transmission. However, any region with inadequate vaccination of domestic dogs is at risk.
Controlling rabies in the dog population through vaccination and public education is crucial to preventing transmission to humans. Prompt post-exposure treatment following a dog bite is also essential to stopping the spread before symptoms develop.
How to prevent rabies from dog saliva
There are several effective ways to prevent transmission of rabies from a dog’s saliva:
- Get dogs vaccinated – Keeping your own dogs up-to-date on their rabies shots is crucial, as vaccinated dogs cannot transmit rabies. According to the CDC, rabies vaccinations should be kept current for all dogs, cats, and ferrets (https://www.cdc.gov/rabies/prevention/index.html).
- Avoid unknown or stray dogs – Do not approach or touch dogs you don’t know, as their rabies vaccine status will be uncertain. Stray dogs in particular may not be vaccinated and could potentially have rabies.
- Wash wounds thoroughly after any animal bite – If you are bitten by a dog, immediately wash the wound with soap and water for at least 15 minutes. This can help reduce the risk of rabies virus transmission.
Following these preventative measures can greatly reduce your risk of contracting rabies from a dog. However, if bitten by an unknown or unvaccinated dog, promptly seek medical care for further treatment and evaluation of rabies risk.
What to do if bitten by a dog
If you are bitten by a dog, the first step is to wash the wound thoroughly with soap and water. Use an antibiotic ointment and bandage the wound. According to the Mayo Clinic, it’s important to wash dog bites with soap under running water for 3-5 minutes to help decrease risk of infection https://www.mayoclinic.org/first-aid/first-aid-animal-bites/basics/art-20056591. You’ll also want to control any bleeding by applying pressure with a clean cloth.
Even if the bite appears minor, it’s recommended to seek prompt medical care. A doctor can assess the risk of rabies transmission and determine if you need the rabies vaccine or other treatment. Mount Sinai notes that medical care should be sought for any animal bite that breaks the skin https://www.mountsinai.org/health-library/selfcare-instructions/animal-bites-self-care. Getting prompt care lowers the risk of rabies and other infections.
Rabies treatment in humans
If a person is potentially exposed to rabies, such as through the bite of an infected animal, swift treatment is critical. There are two main components to rabies post-exposure prophylaxis (PEP):
- Rabies vaccine – The rabies vaccine is given as four doses over 14 days. The first dose should be given as soon as possible after exposure. The rabies vaccine helps the body develop immunity against the rabies virus.
- Rabies immunoglobulin – Rabies immunoglobulin provides immediate, short-term protection until the vaccine kicks in. It is injected at the site of the bite if possible. Rabies immunoglobulin gives a boost to the immune system to more quickly produce rabies antibodies.
According to the CDC, rabies PEP is highly effective in preventing the disease if administered promptly and properly [1]. Studies show that when rabies PEP is given according to guidelines, survival is nearly 100% [2]. Timely rabies vaccination, ideally within 24 hours, is critical for PEP to work [3].
In summary, rabies PEP consisting of the rabies vaccine and rabies immunoglobulin is the standard treatment after potential rabies exposure and is highly effective in preventing the disease when administered promptly.
Rabies survival rates
Rabies is nearly 100% fatal once symptoms start, according to the CDC (https://www.cdc.gov/mmwr/volumes/68/wr/mm6823e1.htm). This is because at that point the rabies virus has spread to the central nervous system and causes inflammation in the brain, leading to death.
However, rabies survival rates are very high if treated immediately after exposure, before symptoms begin. The WHO reports (https://www.who.int/news-room/fact-sheets/detail/rabies) that prompt wound cleansing and vaccination after contact with a suspect rabid animal prevents the onset of rabies in nearly 100% of exposures.
There are only about 15 documented cases of human rabies survivors once symptoms appeared, according to research (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7266186/). These rare survivors received intensive medical interventions like induced comas and antiviral drugs. However, once symptoms start, rabies is almost always fatal within days or weeks.
The key is preventing the onset of symptoms through rapid treatment after any potential rabies exposure. With proper post-exposure prophylaxis, rabies can be prevented nearly 100% of the time.
Key takeaways
Rabies is a viral disease that spreads through the infected saliva of animals. Dogs are one of the most common transmitters of rabies to humans through bites. While simply coming into contact with a dog’s saliva does not guarantee transmission, any dog bite should be treated seriously.
It is crucial to vaccinate dogs against rabies and to seek prompt medical care if bitten by a dog or other animal. With proper post-exposure treatment, rabies can be prevented. However, without treatment, rabies is almost always fatal once symptoms set in. The key is to get medical care as soon as possible after a potential rabies exposure before the virus spreads through the nerves to the brain.
In summary, rabies can spread through the saliva of infected dogs, especially through their bites. However, it is a preventable disease if dogs are vaccinated and people seek prompt medical care after potential rabies exposures. Being aware of rabies risks from dog saliva and knowing what to do can save lives.
