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Symptoms and Signs of Rabies

Doctor's Notes on Rabies

Rabies is a disease seen in humans and other animals due to an animal bite from an animal infected with rabies virus. The most important sign and symptom of rabies is not seen in the person that gets bite, but in recognizing signs and symptoms of rabies in an animal that bites you. In addition, some animals that may bite you may not show any signs and symptoms other than aggression. Consequently, the most important signs and symptoms of rabies is knowing that you’ve received the bite from potentially or actually infected animal. The majority of human rabies cases involve bites from rabid dogs worldwide; in the US, wild animal bites (raccoons, bats, skunks, foxes and coyotes) are the most common sources of rabid animal bites in the US. Signs and symptoms of rabies in animals include vicious, crazed and/or sick appearing animals (for example, muscle spasms, excessive spittle or foam at the mouth); however, some wild animals may appear overly friendly, docile or confused. If you are bitten by an animal, even a dog that has supposedly been vaccinated against rabies, it is important to quickly do two things – go to an emergency department for evaluation and call animal control to determine if the animal has rabies. It is important to do these things quickly because if you wait until you develop signs and symptoms of rabies instead of being treated, the disease is likely to cause your death. Signs and symptoms of rabies in humans include pain, tingling and/or itching at the bite site, then development of fevers, chills, fatigue, muscle aches and irritability develop. Gradually, the individual becomes extremely ill with high fevers, confusion, agitation, spasms of the respiratory musculature when exposed to water or puffs of air (termed hydrophobia or aerophobia), and eventually, seizures, coma and death.

Rabies is caused by infection of an animal or human bite the transfer of the virus and animal saliva or animal bites or even by an infected animal’s scratch. Rarely, rabies may be acquired by contamination of mucous membranes of the nose and mouth by bat secretions in the air of the cave or by virus laboratory workers studying rabies.

Medical Author:
Medically Reviewed on 3/11/2019

Rabies Symptoms

  • Signs and symptoms in animals
    • Animals infected with rabies may appear sick, crazed, or vicious. This is the origin of the phrase "mad dog." However, animals infected with rabies may also appear overly friendly, docile, or confused. They may even appear completely normal.
    • Behavior of animals with rabies may be unusual. For example, seeing a normally nocturnal wild animal during the day (for example, a bat or a fox) or seeing a normally shy wild animal that appears strange or even friendly should raise suspicion that the animal may have rabies.
  • Signs and symptoms in humans
    • The average incubation period (time from infection to time of development of symptoms) in humans is 30-60 days, but it may range from less than 10 days to several years.
    • Most people first develop symptoms of pain, tingling, or itching shooting from the bite site (or site of virus entry).
    • Nonspecific complaints of fevers, chills, fatigue, muscle aches, and irritability may accompany these complaints. These symptoms may appear similar to those of the flu. Early on, these complaints may seem like any virus, except for the shooting sensations from the bite site.
    • Gradually, however, the affected individual becomes extremely ill, developing a variety of symptoms, including high fever, confusion, agitation, and eventually seizures and coma.
    • Typically, people with rabies develop irregular contractions and spasms of the breathing muscles when exposed to water (this is termed hydrophobia). They may demonstrate the same response to a puff of air directed at them (termed aerophobia). By this point, they are obviously extremely ill.
    • Eventually, the various organs of the body are affected, and the person dies despite support with medication and a respirator.
  • A rarer form of rabies, paralytic rabies, has been linked to vampire bat bites outside of the United States. In this form, the person who was bitten develops a paralysis, or inability to move the part of the body that was bitten. This spreads gradually throughout the body, and the person ultimately dies. Hydrophobia is less common in paralytic rabies than in classic rabies.

Rabies Causes

  • For a human to get rabies, two things must happen.
    • First, you must have contact with a rabid animal.
    • Second, the contact must allow for the transmission of infected material, which will involve exposure to the saliva of the infected animal usually through a bite or scratch.
  • Contaminated tissue in the rabid animal includes saliva. Other potentially infectious tissue is in the brain or nerve tissue. The virus is transmitted only when the virus gets into bite wounds, open cuts in your skin, or onto mucous membranes (for example, into your eyes, nose, or your mouth). The virus then spreads from the site of the exposure to your brain and eventually spreads throughout your body's major organs.
  • Ways the virus is transmitted
    • Bites from infected animals are the most common source of transmission.
    • Scratches by infected animals are far less likely to cause infection but are still considered a potential source of rabies transmission.
    • Therefore, treatment might be necessary after a close encounter with a bat.
    • In the large majority of cases of human rabies associated with a bat, a definite history of a bat bite or scratch cannot be confirmed. It is unclear how the virus was transmitted in the other cases -- perhaps by an undetectable bite.
    • Rabies has rarely been transmitted by other means. Examples include organ transplantation, inhaling a large amount of bat secretions in the air of a cave, and inhaling the concentrated virus by laboratory workers studying rabies.

Bad Bugs Identify Bug Bites From Mosquitos, Spiders and More Slideshow

Bad Bugs Identify Bug Bites From Mosquitos, Spiders and More Slideshow

Ticks are often found in plants and brush, and can attach to and bite people and animals. Most tick bites are not harmful; however, ticks can carry serious diseases including Lyme disease and Rocky Mountain spotted fever.

REFERENCE:

Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.