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Rabies
Topic Overview
What is rabies?
Rabies is a disease caused by a virus that can affect the
central nervous system (brain and spinal cord) of any
kind of mammal, including humans.
Animals that are infected with rabies - rabid animals - can spread the disease
through their saliva or brain matter. People who get rabies are almost always exposed from a bite from a rabid animal. Because of widespread animal
vaccination programs, people in the United States rarely get rabies: it is more
common in developing nations.
What causes rabies?
Rabies is caused by a virus that is usually spread through
contact with an infected animal's saliva. In the United States, the rabies
virus is found almost exclusively in wildlife. Bats, raccoons, skunks, foxes,
and coyotes are the most common hosts of rabies. Small mammals such as mice or squirrels almost never have rabies. And there is no known case that they have spread it to humans. Larger rodents, such as woodchucks, are more likely to be rabid. The animals most likely to be
infected with the rabies virus vary by region, although bats are becoming a main source of
infection among humans in many areas of the U.S. and Canada.1
People in Asia, Latin America, Africa and many other countries are most likely to get rabies from dog bites.2, 3
Report all animal bites, especially those from wildlife, to your
local health department. They can tell you which species pose a threat for
rabies in your area. This will help determine the need for preventive
treatment.
Occasionally, the rabies virus can spread to pets, such as dogs,
cats, and domestic ferrets. However, household pets rarely get rabies, due to
successful vaccination programs. A pet that always stays indoors is highly
unlikely to be exposed to the virus.
In extremely rare situations, a person can get rabies without
being bitten by a rabid animal (nonbite exposure). Humans have acquired rabies
by handling a rabid animal or by inhaling airborne virus in places where it
exists in high quantities, such as caves filled with bats.
What are the symptoms?
Signs of rabies in animals may include having excessive saliva or
sometimes foaming at the mouth,
paralysis, or behavioral changes in your pet (such as
shyness when the pet was friendly) or no fear of humans in a wild
animal.
Rabies infection in humans begins with symptoms such as
fever, cough, or sore throat followed in several days by more serious and
rapidly progressing symptoms such as restlessness,
hallucinations, and seizures. The final stage is coma
and death.
The
incubation period—the time from exposure to the rabies
virus until symptoms appear—is usually 4 to 6 weeks. In rare cases, the
incubation period can last from several days to more than a year after exposure
to the virus.
If you are concerned that you may have been exposed to the
rabies virus, it is important to seek medical attention before symptoms
develop. Rabies is nearly always fatal, but shots given before symptoms appear can help prevent the disease.
How is rabies diagnosed?
Rabies in humans can be difficult to diagnose. After symptoms start, tests that can
be done include:
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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.
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Polymerase chain reaction (PCR) assay.
This test finds 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 difficult. Animals that show signs of
abnormal behavior but can't be tested often are assumed to be rabid. 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 behavior of the
animal. Examples include excessive drooling or aggression, a wild animal being unafraid of humans, or an animal that is usually active at night being active in the daytime instead.
- Risk for rabies
in a specific geographic area. For more information, contact your local health
department.
- The date of the animal's last rabies
vaccination.
Can rabies be treated?
After rabies symptoms appear, the disease progresses quickly, and
there is no cure. It is important to get medical care before symptoms occur so that there is less chance of serious damage from the rabies virus. Medical
care for rabies includes:
- Thorough cleansing of the area of exposure
(bite, scratch, or open sore).
- Vaccines and immune globulin.
Any animal bite or area of exposure should be washed with soap
and water immediately. Your doctor and local health department can help
you find out if you have been infected with the rabies virus. Rabies vaccinations will be
given right away if your chance of getting rabies is high.
Frequently Asked Questions
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Learning about rabies:
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Being diagnosed:
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Getting treatment:
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Ongoing concerns:
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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 4 to 6 weeks.4
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 behavioral 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 4 to 6 weeks but can be much longer. 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 behavior that alternate with
bizarre or unusual behavior, such as:
- Fear of water (hydrophobia) or fear of air
(aerophobia).
- Muscle spasms in the face, neck, and/or
diaphragm, followed by
seizures.
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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.
Exams 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 difficult. A lab exam of the animal's brain tissue is needed. Animals that show signs of
abnormal behavior 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 behavior of the animal, such as excessive drooling or
aggression.
- Risk for rabies in a specific geographic area. Your
local health department 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 (euthanized), 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 department
immediately. Trained personnel will attempt to safely capture the
animal. The animal may be observed or killed (euthanized), depending on your
local health department policy. If the animal is euthanized because of its high
risk for having rabies, its brain tissue will be examined. You probably will
undergo 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 department 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 health
professional 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. Consult a health
professional to find out whether further wound care is needed.
Postexposure prophylaxis (PEP)
If you think you have been exposed to rabies, you may be given a series of
shots (injections) known as postexposure 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 department or a doctor can help
determine your risk and whether you need PEP. Factors involved in
determining this risk include:
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Type of exposure. Exposure to the
rabies virus may be through either a bite or a nonbite. Nonbite 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.
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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 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 the United States, PEP has two parts:
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Injection of antibodies. An injection
of human rabies immune globulin (HRIG)
antibodies helps inactivate the rabies virus near the
wound and in the body until your body can make its own
antibodies.
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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, adsorbed (RVA), and
purified chick embryo cell culture (PCEC).
The vaccines and HRIG are usually given at the same time.
Some vaccines
that are not approved for use in the United States or Canada 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 the United States or Canada,
you may be offered one of these vaccines. The World Health Organization (WHO) approves of these vaccines.5 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
preexposure prophylaxis, is often recommended if you
are at high risk of exposure.
Rabies vaccinations may be recommended if you will be traveling
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 traveling with children.6 Contact your doctor or
local public health department 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 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 health professional 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 behavior 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 or state health department
can test the brain for the virus.
- Contact the local or state health
department 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.
(What is a PDF document?) 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
Online Resources
| KidsHealth for Parents, Children, and Teens |
| Nemours Foundation |
| Web Address: | www.kidshealth.org |
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This Web site provides a wide range of information about children's
health, from allergies and diseases to normal growth and development (birth to
adolescence). This Web site offers separate areas for kids, teens, and parents,
each providing age-appropriate information that the child or parent can
understand. You can sign up to get weekly emails about your area of interest.
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| National Center for Infectious Diseases |
| U.S. Centers for Disease Control and
Prevention |
| Web Address: | www.cdc.gov/ncidod |
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The mission of the National Center for Infectious Diseases (NCID)
is to prevent illness, disability, and death caused by infectious diseases in
the United States and around the world. The Web site offers links to
information about specific diseases and general areas of interest.
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Organization
| World Health Organization |
| Avenue Appia 20 |
| 1211 Geneva 27, Switzerland |
| E-mail: | info@who.int |
| Web Address: | www.who.int/en |
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The World Health Organization (WHO), a specialized agency of the
United Nations, has 192 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 and on travelers' health.
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Related Information
References
Citations
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Plotkin SA, Clark FH (2004). Rhabdoviridae: Rabies
virus. In RD Feigin et al., eds., Textbook of Pediatric
Infectious Diseases, 5th ed., vol. 2, pp. 2347–2364. Philadelphia:
Saunders.
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Centers for Disease Control and Prevention
(1999). Human rabies prevention—United States. 1999 recommendations of the
Advisory Committee on Immunization Practices (ACIP). MMWR, 48(RR-1): 1–21.
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Rupprecht CE, Givvons RV (2004). Prophylaxis against rabies. The New England Journal of Medicine, 351: 2626–2635.
-
American Academy of Pediatrics (2003). Rabies. In LK
Pickering, ed., Red Book: 2003 Report of the Committee on
Infectious Diseases, 26th ed., pp. 514–521. Elk Grove Village, IL:
American Academy of Pediatrics.
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World Health Organization (2005). Fact Sheet: Rabies. Available online: http://www.who.int/mediacentre/factsheets/fs099/en/.
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Wilde H, et al. (2003). Rabies update for travel
medicine advisors. Clinical Infectious Diseases, 37:
96–100.
Other Works Consulted
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American Public Health Association (2004). Rabies. In DL Heymann, ed., Control of Communicable Diseases Manual, 18th ed., pp. 438–447. Washington, DC: American Public Health Association.
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Bleck TP, Rupprecht CE (2005). Rhabdoviruses. In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 6th ed., pp. 2047–2056. Philadelphia: Elsevier Churchill Livingstone.
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Hanlon CA, Corey L (2005). Rabies virus and other rhabdoviruses. In DL Kasper et al., eds., Harrison's Principles of Internal Medicine, 16th ed., vol. 1, pp. 1155–1160. New York: McGraw-Hill.
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Krebs JW, et al. (2001). Public veterinary medicine:
Public health. Journal of the American Veterinary Medicine
Association, 219(12): 1687–1699.
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Lewis LM, et al. (2006). Bites and stings. In DC Dale, DD Federman, eds., ACP Medicine, section 8, chap. 2. New York: WebMD.
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Moran GJ, et al. (2000). Appropriateness of rabies postexposure prophylaxis treatment for animal exposure. JAMA, 284(8): 1001–1007.
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National Association of State Public Health
Veterinarians (2001). Compendium of Animal Rabies Prevention and Control, 2001.
MMWR, 50(RR-8): 1–9.
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Rupprecht CE, et al. (2002). Rabies re-examined.
Lancet Infectious Disease, 2(6): 327–343.
Credits
| Author | Amy Fackler, MA |
| Author | Debby Golonka, MPH |
| Editor | Susan Van Houten, RN, BSN, MBA |
| Associate Editor | Pat Truman |
| Primary Medical Reviewer | Adam Husney, MD - Family Medicine |
| Specialist Medical Reviewer | Christine Hahn, MD - Epidemiology |
| Last Updated | September 19, 2006 |
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| Author: | Amy Fackler, MA
Debby Golonka, MPH | Last Updated: September 19, 2006 |
| Medical Review: | Adam Husney, MD - Family Medicine
Christine Hahn, MD - Epidemiology |
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