Rabies

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Rabies

Topic Overview

What is rabies?

Rabies is an infection caused by a virus. It affects the brain and spinal cord (central nervous system) of any kind of mammal, including humans. It is nearly always deadly if not treated before symptoms begin.

Animals that are infected with rabies—rabid animals—can spread the disease through their saliva or brain tissue. People usually get rabies when a rabid animal bites them. It is rare for people in Canada to get rabies. It is more common in developing nations.

How do you get rabies?

Rabies is caused by a virus that usually is spread through an infected animal's saliva. Bats, raccoons, skunks, foxes, and coyotes are the animals most likely to have rabies in Canada and the United States. Small mammals such as mice and squirrels almost never have rabies.

People in Canada and the U.S. are most likely to get rabies from bats.1 People in many other countries are most likely to get rabies from dog bites.2, 3

Report all animal bites to your local health unit. Experts there can help you decide whether you need treatment.

Sometimes the rabies virus can spread to pets, such as dogs, cats, and ferrets. But household pets rarely get rabies, because most of them get rabies vaccines. Pets that stay indoors are very unlikely to get rabies.

It’s possible to get rabies even when you don't see an animal bite. For example, bat bites or scratches may be so small that you don't notice them. If you or your children come in direct contact with a bat, or if you find a bat in a closed room with a sleeping person, call your doctor right away. People also can get rabies by handling animals with rabies or inhaling the virus, but these cases are rare.

What are the symptoms?

Signs of rabies in animals may include drooling, foaming at the mouth, or paralysis. A pet with rabies also may behave differently than usual, such as acting shy when the pet usually is friendly. A wild animal with rabies may have no fear of humans.

Rabies in humans begins with symptoms such as fever, cough, or sore throat. Later, symptoms become more serious and can include restlessness, hallucinations, and seizures. The final stage is coma and death.

As soon as symptoms appear, it’s too late for a cure. Rabies is nearly always deadly. The time from exposure to the rabies virus until symptoms appear usually is 2 to 3 months. In rare cases, it may be shorter or much longer.

If you believe you were exposed to the rabies virus, it is very important to get medical care before symptoms begin.

What should you do if you think you have been exposed to rabies?

First, wash the animal bite, scratch, or open sore with soap and water. Then call your doctor and local health unit right away. They can help you find out if you have been infected with the rabies virus.

If you have been bitten by or exposed to an animal that is at low risk for having rabies, such as a pet, the animal will be captured by people trained to handle rabid animals. It will be watched for signs of rabies. Because rabies is deadly, your doctor may not wait to find out if the animal has rabies. If the doctor thinks there’s a chance that the animal is rabid, you will start to get a series of shots right away. These shots help your body’s immune system destroy the disease in its early stages.

If you have been bitten by or exposed to an animal that is at high risk for having rabies, you will start getting the shots right away. If possible, the animal will be watched for signs of rabies or will be killed for testing. If it is found to have rabies, you will continue the series of shots. But if the animal doesn't have rabies, you can stop getting the shots.

If an animal shows signs of rabies but can't be captured for testing, it often is assumed to be rabid.

Frequently Asked Questions

Learning about rabies:

Being diagnosed:

Getting treatment:

Ongoing concerns:

Symptoms

After the symptoms of rabies appear, the disease is nearly always fatal. The virus damages the central nervous system, which includes the brain and spinal cord.

To prevent rabies, you must get care before symptoms develop. Symptoms in humans may take from several days to more than a year to appear, although most people have signs of disease within 2 to 3 months. Medical care to prevent rabies is advised even if symptoms do not appear soon after exposure to the virus.

Signs in animals

Rabid animals—those infected with rabies—may display noticeable signs or behavioural changes. An animal that has bitten someone and is or was acting strangely may be rabid.

It is important to observe the animal when possible in order to provide proper and timely preventive treatment to any person who may have been exposed. An animal that shows any of the following signs may have rabies:

  • No fear of humans shown by a wild animal
  • Shyness in a usually friendly pet
  • Restlessness, excitability, aggression, or sudden mood changes
  • Excessive drooling
  • An animal that is normally active at night (such as bats, raccoons, and skunks) being active during the day
  • Eating substances not normally eaten (pica)
  • Paralysis, which is sometimes the only sign

Symptoms in humans

The typical incubation period for rabies is 2 to 3 months. In rare cases, the incubation period can last from several days to more than a year after exposure to the virus. During the incubation period, there are usually no symptoms of rabies. Early symptoms include pain and numbness at the site of the bite followed by vague symptoms that are often confused with those of other conditions. These include:

  • Fever.
  • Cough or sore throat.
  • Pain, burning, itching, tingling, or numbness at the site of the bite or original exposure.
  • Abdominal pain.
  • Anxiety or restlessness that gradually gets worse and may become extreme agitation.

Later symptoms are more distinctive and may include:

  • Periods of normal behaviour that alternate with bizarre or unusual behaviour, such as:
  • Fear of water (hydrophobia) or fear of air (aerophobia).
  • Muscle spasms in the face, neck, and/or diaphragm, followed by seizures.
  • Paralysis, which is often the only symptom of the less common paralytic form of rabies often associated with rabies from vampire bats.
  • Wide fluctuations in temperature, pulse, and blood pressure.
  • Coma, and heart and respiratory failure.

Examinations and Tests

Rabies in humans can be difficult to diagnose. After symptoms start, tests that can be done include:

  • Direct fluorescent antibody (DFA) test. This common, rapid test detects the rabies virus protein. DFA testing is done by taking a sample of tissue from the potentially affected area.
  • Polymerase chain reaction (PCR) assay. This test detects the genetic material (DNA) of the rabies virus proteins. PCR testing is very accurate and can be done on saliva, cerebrospinal fluid, or tissue.

To find out if a person was exposed to the rabies virus, the animal must be tested. Diagnosis in animals also is hard. A lab examination of the animal's brain tissue is needed. Animals that show signs of abnormal behaviour but can't be tested often are assumed to be rabid. (For more information, see the Symptoms section of this topic.) The risk that an animal is infected with the rabies virus is based on:

  • The type of animal. Some animals are more likely to carry rabies than others. Bats, skunks, raccoons, foxes, and coyotes are common carriers of the rabies virus.
  • The behaviour of the animal, such as excessive drooling or aggression.
  • Risk for rabies in a specific geographic area. Your local health unit will have information about the risk of rabies in your area.
  • The date of the animal's last rabies vaccination.

If you have been bitten by or exposed to a potentially rabid animal, you may be given a series of shots while you are waiting for test results. These shots are given to help prevent you from getting rabies before tests confirm whether or not you have been exposed to it.

Bites from or exposure to a low-risk animal

If you are bitten by or exposed to an animal at a low risk for having rabies, such as a domestic dog, cat, or ferret, the animal should be captured by authorities specifically trained to capture rabid animals, quarantined, and observed for 10 days.

  • If the animal does not show signs of rabies in that time span, the animal is assumed to be free of rabies at the time of the bite, and you will not need treatment.
  • If the animal starts having signs of rabies or dies in that time span, you will begin preventive treatment for the disease. An animal with signs of rabies will be killed (euthanised), and its brain tissue will be tested to confirm whether it had rabies. It takes only a few hours to test the brain tissue after it is received by the appropriate lab. If the test results show that the animal does not have rabies, you can stop preventive treatment.

Bites from or exposure to a high-risk animal

If you are bitten by or exposed to an animal that you think may have rabies, contact your local health unit immediately. Trained personnel will attempt to safely capture the animal. The animal may be observed or killed (euthanised), depending on your local health unit policy. If the animal is euthanised because of its high risk for having rabies, its brain tissue will be examined. You probably will begin preventive treatment until testing on the animal can be completed.

  • If the animal does not have rabies, you can stop preventive treatment.
  • If the animal has rabies, you need to complete treatment.

Sometimes the animal suspected of having rabies cannot be caught. Contact your local health unit to find out which species of animals pose a threat for rabies in your specific area. This information will help determine whether medical care is needed.

Rabies infection can occur even when there is no noticeable animal bite involved. Bats, in particular, are generally very small animals, and in many cases their bites or scratches may not be noticeable. If you or your children come in direct physical contact with a bat, or a bat is found in a room with a sleeping or unconscious person, contact a doctor immediately.

Talk to your children about avoiding bats and other wild animals.

Treatment Overview

After possible exposure to the rabies virus, proper wound care and vaccinations are the most effective methods to stop the spread of infection.

Wound care

If you are bitten or scratched by an animal, clean the wound immediately with plenty of soap and water to reduce the chance of infection. Call a doctor to find out whether further wound care is needed.

Post-exposure prophylaxis (PEP)

If you think you have been exposed to rabies, you may be given a series of shots (injections) known as post-exposure prophylaxis (PEP). The shots help the body's immune system destroy the disease in its early stages. Getting PEP before symptoms appear usually prevents infection, and you are likely to recover. After symptoms of rabies are present, PEP is thought to not be effective.

PEP is given depending upon your risk of exposure to rabies. Your local health unit or a doctor can help determine your risk and whether you need PEP. Factors involved in determining this risk include:

  • Type of exposure. Exposure to the rabies virus may be through either a bite or a non-bite. Non-bite exposures (which occur when an open cut in the skin or mucous membrane is exposed to the rabies virus) rarely lead to rabies but will need treatment.
  • Type of animal involved. Some animals are more likely to carry rabies than others. Bats, skunks, raccoons, foxes, and coyotes are common carriers of the rabies virus in Canada and the United States. People in Asia, Latin America, Africa and many other countries are most likely to get rabies from dog bites.2, 3

In Canada and the U.S., PEP has two parts:

  • Injection of antibodies. An injection of human rabies immunoglobulin (HRIG) antibodies helps inactivate the rabies virus near the wound and in the body until your body can make its own antibodies.
  • Vaccination series. A series of shots with a vaccine helps your immune system increase its own response against the rabies virus. Vaccines for rabies include the human diploid cell vaccine (HDCV), rabies vaccine, and purified chick embryo cell culture (PCEC). Another type of rabies vaccine called rabies vaccine adsorbed (RVA) is used in the United States and other countries, but not in Canada.

The vaccines and HRIG are usually given at the same time.

Some vaccines that are not approved for use in Canada or the U.S. are used in developing countries. These sometimes are given in a series of fewer shots or are injected in the area under the skin rather than into muscle. Some vaccines used in other countries and some older vaccines are made from nerve tissue. These vaccines may cause more adverse reactions than newer vaccines.

If you are exposed to rabies outside Canada or the U.S., you may be offered one of these vaccines. The World Health Organization (WHO) approves of these vaccines.4 If you have any choice, request HDCV, RVA, or PCEC. If these are not available, it is better to accept one of the other vaccines with more risk of an adverse reaction than to get no vaccine at all. As soon as you are able to return home, ask your doctor about whether you should receive any more vaccines.

Preventive vaccination

Certain jobs or hobbies or frequent travel to developing countries may present a greater risk of exposure to rabies. Preventive vaccination, or pre-exposure prophylaxis, is often recommended if you are at high risk of exposure.

Rabies vaccinations may be recommended if you will be travelling in rural areas of countries where rabies is a risk. In many developing countries throughout Asia, Africa, and Central and South America, rabies is much more common, with the majority of human infections caused by dog bites. Because children are at a greater risk of animal bites than adults and because bites to children tend to be more severe, vaccinations may be recommended if you will be travelling with children.5 Contact your family doctor, local travel clinic, or local public health unit for more information.

After symptoms develop

After symptoms of rabies appear, intensive medical care can maintain the heart, lungs, and other vital organs for a while, but death will usually occur. In extremely rare cases, the immune system may overcome the infection with the help of vaccinations and antiviral medicines. If you have had any contact with an animal that may have rabies, seek medical treatment immediately.

Home Treatment

Home treatment for rabies is limited to preventing contact with the virus, getting immediate and appropriate treatment for an animal bite, and obtaining medical assistance to help find out your rabies exposure risk.

Preventing contact with rabies virus

To avoid contact with the rabies virus:

  • Have pet dogs, cats, and domestic ferrets vaccinated against rabies. If your pet was previously owned, ask for certification of rabies vaccination. Veterinarians usually provide a certificate when they give vaccines. If no document exists, confirm with the pet's veterinarian that the pet received the rabies vaccine.
  • Avoid contact with stray dogs, especially when travelling in rural areas of countries where rabies is a risk.
  • Avoid all contact with bats. Many cases of human rabies in North America are linked to contact with bats.1
  • Never touch or try to pet or catch wild animals such as raccoons, skunks, foxes, and coyotes. Teach children to avoid these animals.
  • Secure garbage and other materials that attract animals.
  • Secure open areas of your home, such as pet doors, chimneys, unscreened windows, or any place that wild or stray animals could enter.
  • Never handle a dead animal. In particular, avoid any contact with the brain tissue from a dead animal.

Self-care for an animal bite

After an animal bite or other risky contact:

  • Immediately clean the wound or area of contact thoroughly with soap and water. Consult a doctor for further wound care instructions.
  • If the animal is a dog, cat, or domestic ferret, try to locate and contact the owner. If you can't find the owner, contact the local animal control to safely capture the animal.
  • If the animal is wild, do not attempt to capture or destroy it. Identify the species of animal and notice whether its behaviour is unusual. If you have already killed the animal, keep the head, but do not touch the brain, which may transmit the virus. The local health unit can test the brain for the virus.
  • Contact the local health unit to report a bite or serious scratch. That agency will know whether the animal species is likely to be infected with rabies in your area. Officials also may try to capture or destroy a wild animal so that it can be tested.
  • Evaluate the need for tetanus immunization. This immunization protects against tetanus (lockjaw), a bacterial infection that can occur when tetanus bacteria get in a wound. After the initial childhood tetanus immunization schedule has been completed, a tetanus and diphtheria (Td) booster is recommended every 10 years. You should receive a booster when an injury has caused a dirty or contaminated wound and it has been 5 years since your last Td booster (or the date of the last booster is unknown). A tetanus shot is needed within 48 hours of the injury.

Other Places To Get Help

Organizations

Public Health Agency of Canada (PHAC)
130 Colonnade Road
A.L. 6501H
Ottawa, ON  K1A 0K9
Phone: Telephone numbers for PHAC vary by region. For your regional number, go to the listing on the PHAC Web site at www.phac-aspc.gc.ca/contac-eng.php.
Web Address: www.phac-aspc.gc.ca/index-eng.php
 

The Public Health Agency of Canada (formerly the Population and Public Health Branch of Health Canada) is primarily responsible for policies, programs, and systems relating to disease prevention, health promotion, disease surveillance, community action, and disease control.


World Health Organization
Avenue Appia 20
1211 Geneva 27, Switzerland  
Email: info@who.int
Web Address: www.who.int/en
 

The World Health Organization (WHO) is an agency of the United Nations. It has about 200 member states. WHO promotes technical cooperation among nations on health issues, carries out programs to control and eliminate disease, and strives to improve the quality of human life.

The Web site has information on many health topics, including health and disease related to travel.


References

Citations

  1. Plotkin SA, et al. (2009). Rhabdoviridae: Rabies virus. In RD Feigin et al., eds., Feigin and Cherry’s Textbook of Pediatrics Infectious Diseases, 6th ed., vol. 2, pp. 2494–2511. Philadelphia: Saunders Elsevier.
  2. Centers for Disease Control and Prevention (2008). Human rabies prevention—United States 2008. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR, 57(Early Release): 1–28. Available online: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5703a1.htm?s_cid=rr5703a1_e.
  3. Rupprecht CE, Givvons RV (2004). Prophylaxis against rabies. New England Journal of Medicine, 351: 2626–2635.
  4. World Health Organization (2008). Fact Sheet: Rabies. Available online: http://www.who.int/mediacentre/factsheets/fs099/en.
  5. Wilde H, et al. (2003). Rabies update for travel medicine advisors. Clinical Infectious Diseases, 37: 96–100.

Other Works Consulted

  • American Public Health Association (2008). Rabies. In DL Heymann, ed., Control of Communicable Diseases Manual, 19th ed., pp. 498–508. Washington, DC: American Public Health Association.
  • Bassin SL, et al. (2010). Rhabdoviruses. In GL Mandell et al., eds., Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, 7th ed., vol. 2, pp. 2249–2258. Philadelphia: Churchill Livingstone Elsevier.
  • Centers for Disease Control and Prevention (2010). Use of a reduced (4-dose) vaccine schedule for postexposure prophylaxis to prevent human rabies. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR, 59(RR02): 1–9. Available online: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5902a1.htm?s_cid=rr5902a1_e.
  • Jackson AC, Johannsen EC (2008). Rabies virus and other rhabdovirus infections. In AS Fauci et al., eds., Harrison's Principles of Internal Medicine, 17th ed., vol. 1, pp. 1222–1226. New York: McGraw-Hill.
  • Lewis LM, et al. (2006). Bites and stings. In DC Dale, DD Federman, eds., ACP Medicine, section 8, chap. 2. New York: WebMD.
  • National Association of State Public Health Veterinarians, Inc. (2008). Compendium of animal rabies prevention and control, 2008. MMWR, 57(RR-02): 1–9. Available online: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5702a1.htm.
  • Peterson LR, Gubler DJ (2006). Viral zoonoses. In DC Dale, DD Federman, eds., ACP Medicine, section 7, chap. 31. New York: WebMD.
  • Toltzis P (2007). Rabies. In RM Kliegman et al., eds., Nelson Textbook of Pediatrics, 18th ed., pp. 1423–1426. Philadelphia: Saunders Elsevier.
  • Wikerson JA (2007). Rabies. In PS Auerbach, ed., Wilderness Medicine, 5th ed., pp. 1206–1225. Philadelphia: Mosby Elsevier.

Credits

By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Primary Medical Reviewer Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Last Revised October 27, 2010

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