Rabies is a dangerous virus that causes brain inflammation in humans and other mammals. Animals carrying the infection can spread rabies to humans through bites and scratches.

Without treatment, the disease can be fatal. However, it is treatable if a person who has had exposure to rabies seeks immediate medical attention.

In the United States, between 1 and 3 people contract rabies each year. From 2008 to 2019, the U.S. saw 25 human cases of the disease, with eight involving people contracting rabies outside the country. Since the 1970s, advances in medicine, awareness, and vaccination programs have reduced the incidence of rabies.

However, the disease remains a problem worldwide and causes tens of thousands of deaths annually, mostly in rural areas of Southeast Asia and Africa. Of all infections involving rabies, 99% occur due to dog bites.

Here are some facts about rabies:

  • Rabies is a viral disease that nearly always occurs due to transmission by an animal bite carrying the infection.
  • Anyone who receives a bite in a geographical area where rabies occurs should seek immediate treatment.
  • For treatment to succeed, it must take place before symptoms appear.
  • Symptoms include neurological problems and a fear of light and water.
  • Following the vaccination requirements for pets helps prevent and control rabies.

Rabid dog with rabies.Share on Pinterest
Aggressive behavior of a caged canine, suspected of being rabid, 1980. Smith Collection/Gado/Getty Images

Rabies is a viral infection that primarily spreads through a bite from an infected animal. Without early treatment, it is usually fatal.

It is an RNA virus of the rhabdovirus family that can affect the body in one of two ways. It can enter the peripheral nervous system directly and migrate to the brain. It can also replicate within muscle tissue, where it is safe from the host’s immune system. From here, it enters the nervous system through the neuromuscular junctions.

Once inside the nervous system, the virus produces acute inflammation of the brain. Coma and death soon follow.

There are two types of rabies. The first type, furious or encephalitic rabies, occurs in 80% of human cases, and a person with it is more likely to experience hyperactivity and hydrophobia. The second type, called paralytic or “dumb” rabies, causes paralysis as a dominant symptom.

Rabies is most common in countries where stray dogs are present in large numbers, with Asia and Africa accounting for 95% of cases.

As saliva carries the virus, rabies can develop if an infected animal bites someone. It can also occur if saliva from an infected animal gets into an open wound or through a mucous membrane, such as the eyes or mouth. However, the virus cannot pass through unbroken skin.

In the U.S., raccoons, coyotes, bats, skunks, and foxes are the animals most likely to spread the virus. Bats carrying rabies exist in all U.S. states except Hawaii.

Any mammal can harbor and transmit the virus, but smaller mammals, such as rodents, rarely become infected or transmit rabies. Rabbits are also unlikely to spread rabies.

Rabies progresses in five distinct stages:

  • incubation
  • prodrome
  • acute neurologic period
  • coma
  • death

Incubation

Incubation is the time before symptoms appear. It usually lasts from 2–3 months and varies from 1 week to 1 year, depending on where the virus entered the body and the number of viral particles involved. The closer the bite is to the brain, the sooner the effects are likely to appear.

By the time symptoms appear, rabies is usually fatal. Anyone who has exposure to the virus should seek medical help immediately, without waiting for symptoms.

Prodrome

During prodrome, early, flu-like symptoms occur, including:

Acute neurologic period

During this stage, neurologic symptoms develop, including:

  • confusion and aggression
  • partial paralysis
  • involuntary muscle twitching
  • rigid neck muscles
  • convulsions
  • hyperventilation and difficulty breathing
  • hypersalivation, or producing a lot of saliva
  • frothing at the mouth
  • fear of water, or hydrophobia
  • hallucinations, nightmares, and insomnia
  • priapism, or permanent erection, in males
  • photophobia, or a fear of light

Toward the end of this phase, breathing becomes rapid and inconsistent.

Coma and death

A person may enter a coma, and most people then die within 3 days. During the coma stage, even with supportive therapy, virtually no person survives rabies.

Why does rabies cause a fear of water?

People used to call rabies hydrophobia because it appears to cause a fear of water. The reason is that the infection causes intense spasms in the throat when a person tries to swallow. Even the thought of swallowing water can cause spasms, making it appear that the individual is afraid of water.

If doctors are not certain that an individual received a bite from an animal infected with rabies, they typically must exclude other conditions first.

Healthcare professionals may perform multiple tests without concluding the individual has rabies. Laboratory tests may show antibodies, but these may not appear until later in the development of the disease. Doctors could potentially isolate the virus from a person’s saliva or through a skin biopsy. However, by the time they confirm a diagnosis, it is often too late to act.

For this reason, the individual usually starts a course of prophylactic treatment immediately without waiting for a confirmed diagnosis.

If a person develops symptoms of viral encephalitis following an animal bite, doctors should treat them as if they may have rabies.

If a person has a bite or scratch from an animal that may have rabies, or if the animal licks an open wound, the individual should immediately wash any bites and scratches for 15 minutes with soapy water, povidone iodine, or detergent. This might minimize the number of viral particles. They must then seek immediate medical attention.

After exposure and before symptoms begin, a series of shots can treat potential rabies infections. Because doctors do not usually know whether the animal had rabies, it is safer to assume that they do and begin vaccination.

A small number of people have survived rabies, but most cases are fatal once symptoms develop, and there is no effective treatment at this stage. Instead, healthcare professionals will usually try and make a person with symptoms as comfortable as possible. These individuals may also need breathing assistance.

Rabies vaccine

Doctors do not offer the rabies vaccine routinely. Instead, they reserve it for those at high risk of rabies exposure, such as laboratory staff working with the virus that causes the disease, veterinarians, and people likely to receive animal bites. These individuals may receive regular vaccinations.

Other people may receive the vaccine following exposure to the virus after an animal bite. This is called postexposure prophylaxis.

Rabies vaccine contains an inactivated or a harmless version of the rabies virus, so it cannot cause the disease. It triggers the immune response to produce antibodies, which remain in the body and help protect against future rabies infections.

Doctors administer the rabies vaccine into the upper arm. Preexposure protection requires three doses of rabies vaccine across 28 days.

For post-exposure protection, previously unvaccinated people need four doses of the rabies vaccine, plus rabies immune globulin (RIG). Doctors administer RIG as soon as possible, close to the bite wound, to prevent the virus from causing infection in the individual. According to the World Health Organization (WHO), there are various ways of achieving this depending on the scheduling and frequency of vaccines.

Rabies is a serious disease, but individuals and governments can take steps to prevent infections.

Strategies include:

  • regular rabies vaccinations for pets and domestic animals
  • bans or restrictions on the import of animals from certain countries
  • widespread vaccinations of humans in some areas
  • educational information and awareness
  • enhanced access to medical care to people who receive bites

In rural Canada and the U.S., agencies have dropped bait containing an oral vaccine to reduce the number of wild animals with rabies.

Individual precautions

Individuals should follow some safety rules to reduce the chance of contracting rabies.

  • Vaccinate pets: Find out how often to vaccinate cats, dogs, ferrets, and other domestic or farm animals, and keep the vaccinations up to date.
  • Protect small pets: Some pets cannot have vaccinations, so their owners must prevent contact with wild animals.
  • Keep pets confined: Owners should confine pets safely while at home or supervise them.
  • Report strays to local authorities: Contact local animal control officials or police departments regarding stray animals.
  • Do not approach wild animals: Animals with rabies are likely to be less cautious than usual and may approach people.
  • Keep bats out of the home: Seal houses to prevent bats from nesting and call an expert to remove any bats present.

In the U.S., vaccinations can control rabies in domestic dogs. Nevertheless, between 30,000 and 60,000 people seek rabies postexposure prophylaxis every year, following contact with suspect animals.

People report between 60 and 70 dogs and around 250 cats as rabid each year in the U.S. Most of these have not been vaccinated and encountered the virus through wild animals, such as bats.

The prevalence of rabies varies widely in different countries. In nations without a feral dog population, the rates are significantly lower.

Rabies is present in 150 countries and all continents except Antarctica and the Arctic. The disease is most common in Africa and Asia, with India having the highest number of cases.

In recent years, the prevalence of rabies in South America and the Caribbean has fallen significantly due to rabies control programs. Official figures show that there were 250 cases in 1990, but by 2010, there were fewer than 10.

Anyone traveling to an area where rabies is prevalent or participating in activities where they are likely to come into contact with wild animals, such as caving or camping, should ask their doctor about vaccinations.

Rabies is a deadly virus that infected animals spread through their saliva. It causes flu-like symptoms initially, which progress into fever, muscle spasms, coma, and eventually, death.

Although there is no effective treatment once symptoms appear, rabies vaccines are usually successful in preventing infections. However, people must seek treatment immediately and not wait for any symptoms.

Individuals at high risk of rabies infections, such as veterinarians, should have preexposure vaccinations. Anyone who has a bite from a potentially infected animal should receive immediate medical attention and post-exposure vaccinations. They may also require fast-acting RIG if they have not already had the vaccine for the virus.