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Patient information: Rabies (Beyond the Basics)

RABIES OVERVIEW

Rabies is a disease caused by a virus that, with very rare exceptions, is always fatal. It is spread through bites or scratches from infected animals. The virus infects the brain, causing an animal to exhibit unusual, often aggressive, behavior. The rabies virus is present in the saliva of the infected animal and is spread when the saliva gets into a bite or scratch. The risk of getting rabies is greater if a person is bitten multiple times or if the bites are close to or on the head.

In developing countries, 90 percent or more of rabies cases in humans are caused by dog bites. In the United States, rabies in dogs has been largely eliminated as a result of animal vaccination and control. Wild bats now pose the greatest risk of rabies to humans, although rabies in raccoons, skunks, and foxes pose the greatest risk to domestic animals.

This topic discusses strategies to prevent rabies after being bitten or exposed to an infected animal or animal suspected of having rabies. Animal bites are discussed in a separate article. (See "Patient information: Animal bites (Beyond the Basics)".)

POST-BITE RABIES PREVENTION

Rabies infection can be prevented, even after a bite or a scratch from an infected animal occurs.

Rabies vaccine and immune globulin — A series of injections, including rabies vaccine and human rabies immune globulin (RIG) can prevent rabies, even if the virus enters the body. This preventive strategy is called post-exposure prophylaxis. RIG contains antibodies against the rabies virus and provides immediate protection against rabies infection, whereas the rabies vaccine provides protection within approximately two weeks.

Side effects of rabies vaccine and RIG can include discomfort at the injection site (similar to a flu shot), low-grade fever, and mild muscle aches. If needed, rabies post-exposure prophylaxis is safe to give to children and pregnant women who need post-exposure prophylaxis.

Wounds should be washed with soap and lots of water and may be rinsed with an antiseptic. This will reduce the risk of the rabies virus entering the body. (See "Rabies immune globulin and vaccine".)

When is rabies prophylaxis needed? — Certain information is needed to determine if post-exposure rabies prophylaxis is needed. This includes:

Whether the person was bitten or scratched, and the location of the wounds

The type of animal involved (table 1)

Whether the exposure was provoked or unprovoked (animals infected with rabies are more likely to attack, even when not provoked)

Whether the animal was previously vaccinated against rabies

The presence of rabies in that animal species in the region

The availability of the animal for testing or observation

Immediate treatment recommended — A person with a high risk exposure to an animal that is, or may be, infected with rabies should be given immediate post-exposure prophylaxis with rabies vaccine and RIG. If the animal is not available for observation or testing, and is determined to be at high risk of having rabies, most experts recommend post-bite rabies prophylaxis because of the risk of fatal illness caused by infection with the rabies virus. (See "When to use rabies prophylaxis".)

If post-exposure prophylaxis is needed:

The rabies vaccine should be given as soon as possible (considered day zero for the immunization schedule). The rabies vaccine is given into a muscle, usually in the upper arm. The rabies vaccine is given again on the third, seventh, and fourteenth day after the exposure. A fifth dose of rabies vaccine was previously recommended, but experts now agree that this is not necessary unless an individual has a medical condition that might interfere with their ability to respond to the vaccine.

One dose of RIG is also given on day zero. As much of the RIG dose as possible is injected into and around the wound(s).

Some people have received rabies prophylaxis before exposure (eg, veterinarians, veterinary technicians, animal control officers, people visiting places of higher risk of rabies exposure). These persons only require two doses of rabies vaccine on days zero and three. No RIG is necessary for people who have previously received the rabies vaccine.

Defer treatment during observation period — If the animal is a healthy pet, such as a dog, cat or ferret, and the animal is available for observation, rabies prophylaxis can be delayed while the animal is observed (in a secure facility, such as a veterinary clinic) for 10 days. If the animal develops signs of rabies, post-bite rabies vaccine and immune globulin should be started immediately. (See 'Rabies vaccine and immune globulin' above.)

If the animal remains healthy during the 10-day observation, the bite victim does not need vaccine or immune globulin.

Indirect exposure — Many people receive post-exposure prophylaxis in circumstances of "indirect exposure". For example, if a pet dog gets into a fight with a rabid or potentially rabid wild animal, the owner will frequently comfort their pet immediately. If there is infectious saliva from the attacking animal on the pet and this saliva gets into a break in the owner's skin, other open wound, eye, nose, or mouth, there is a theoretical risk of rabies.

However, there have never been any reports of a human case of rabies resulting from this type of exposure. For the virus to be infectious and for any risk to exist, the person must be exposed to wet saliva from the rabid animal.

The need for post-exposure prophylaxis in cases of indirect exposure should be discussed with a public health official. In the United States, further information is available from the Centers for Disease Control and Prevention (www.cdc.gov/rabies/).

RABIES AND TRAVEL

Rabies is still quite common in many developing countries. When traveling to countries where rabies is more common, you should avoid approaching and touching all wild and domestic animals. If you are bitten or scratched, you should wash the area immediately and seek expert advice about the need for post-exposure prophylaxis.

In developing countries, the availability and type of rabies vaccine and immune globulin varies considerably. If a person has a high risk exposure to rabies, he or she should consult with a reliable source of information for care.

Pre-exposure rabies vaccination may be recommended if you are traveling to a developing country and might be living in conditions where exposure to rabid and potentially rabid animals is likely. The decision to have pre-exposure rabies vaccination should be discussed with a healthcare provider who is knowledgeable about travel medicine (eg, an infectious disease physician).

It is important to know that having pre-exposure rabies vaccination does not eliminate the need for future vaccination if you are bitten. If you have had the rabies vaccine previously and are bitten or scratched by a rabid animal, you need two doses of rabies vaccine, on days zero and three; no rabies immune globulin is needed. (See "Patient information: Vaccines for travel (The Basics)".)

ADVICE REGARDING SPECIFIC ANIMALS AND RABIES

Contact with wild and unfamiliar domestic animals should always be avoided. Wild animals should not be kept as pets and should never be handled by people who are not properly trained and vaccinated.

Domestic animals — In the United States, dogs, cats, or ferrets that have received rabies vaccination are unlikely to be infected with rabies. The number of rabies cases among domestic animals, such as dogs and cats, declined markedly in the United States in the 1930 and 40s due to rabies vaccination.

While vaccinated animals present little risk, domestic animals must be up-to-date on rabies booster vaccination to assure their protection. Rabies booster vaccines are given every one to four years, depending upon the vaccine used.

The likelihood of rabies in domestic animals is small and varies by region. In the United States, rabies is most often reported in dogs along the United States-Mexico border and in cats in areas of rabid raccoon activity. However, sporadic cases of rabies develop in domestic animals outside of these areas.

Domestic animals that have been imported from areas of the world where rabies is more common have occasionally developed rabies after arrival; these animals can be a threat to humans and other animals.

Wild animals — Bites from wild animals are considered to carry a risk of rabies unless proven otherwise by testing. Post-exposure prophylaxis should be given immediately to anyone who is bitten or scratched unless the animal is caught and tested promptly. In the United States, raccoons, skunks, foxes, bats, and coyotes are the most commonly infected species.

Among large rodents, rabies has been reported in woodchucks and beavers in areas where raccoon rabies is common. Small rodents, such as squirrels, chipmunks, rats, hamsters, gerbils, guinea pigs, mice, and lagomorphs, such as rabbits, are almost never found to be rabid, and there has never been a reported case of rabies transmission to a human from one of these animals. These animals are capable of developing rabies, although this is unlikely because small animals are usually killed or severely injured during an attack by a rabid animal.

Pet rabbits and rodents that are caged outdoors are at risk of exposure to rabid wild animals. The pet could survive the exposure and could potentially develop rabies. Decisions about post-exposure prophylaxis for people bitten by such animals must be made depending upon the individual situation.

Livestock — Among all types of domestic livestock, rabies is most likely to occur in cows. Horses, goats and other livestock species are rarely affected. Anyone who is bitten by livestock should be managed individually, in consultation with local public health authorities.

Bats — Among 54 reported cases of human rabies in the US between 1990 and 2011, 45 cases (83 percent) were caused by a bat strain of rabies.

Anyone who is bitten or scratched by a bat should receive post-exposure prophylaxis, unless the bat can be collected and tests negative for rabies. However, under certain circumstances, bats can bite and transmit rabies without the victim being aware of the bite. As a result, the following precautions are recommended:

Post-exposure prophylaxis is recommended if a person has direct physical contact with a bat, unless the exposed individual is certain that there was no bite or scratch or the bat was tested and found not to be rabid.

Bats should never be kept as pets and should not be picked up or handled by anyone, except those who are trained and have received rabies vaccination. If a bat is found in a home, avoid touching it. If no person or pet was exposed to the bat, if possible, it should be allowed to escape outdoors. If it is not feasible to allow the bat to escape, advice about safely capturing the bat is available at http://www.cdc.gov/rabies/bats/contact/capture.html. Individuals can also contact their local health department with questions about assessing a potential rabies exposure and/or testing captured bats.

SUMMARY

Post-exposure rabies prophylaxis, with both vaccine and rabies immune globulin, is recommended immediately if a biting or scratching animal has rabies or is suspected to have rabies. Anyone who is bitten or scratched by a bat should always receive post-exposure prophylaxis, unless the bat can be collected and tested for rabies.

If a biting or scratching dog, cat or ferret is healthy and available for observation, it should be observed for 10 days. If the animal remains healthy during the 10-day observation, then the bite victim was not exposed to rabies and does not need rabies vaccine or rabies immune globulin. If the animal develops signs of rabies during the 10 days, the exposed person should receive rabies vaccine and immune globulin immediately. There is no recommendation for a 10-day observation of other animals because of lack of data about virus in the saliva.

Post-exposure prophylaxis may be needed immediately if a bite from a high risk animal involves the head or neck. If the animal is not rabid, as determined by either testing or observation, the regimen can be discontinued.

If the animal is not available for observation and it is determined to present a risk for rabies, most healthcare providers recommend post-exposure rabies prophylaxis because of the risk of serious illness caused by rabies virus infection and the safety of the currently available rabies immune globulin and rabies vaccine.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient information: Rabies (The Basics)
Patient information: Animal bites (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient information: Vaccines for travel (The Basics)
Patient information: Animal bites (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Approach to the patient with a suspected spider bite: An overview
Bites of recluse spiders
Clinical manifestations and diagnosis of rabies
Immunizations for travel
Pasteurella infections
Rabies immune globulin and vaccine
Soft tissue infections due to dog and cat bites
When to use rabies prophylaxis
Zoonoses from cats
Zoonoses from dogs
Zoonoses from pets other than dogs and cats

The following organizations also provide reliable health information.

National Library of Medicine

     (www.nlm.nih.gov/medlineplus/healthtopics.html)

Centers for Disease Control and Prevention (CDC)

     Toll-free: (800) 311-3435
     (www.cdc.gov)

World Health Organization

     (www.who.int/rabies/human/postexp/en/index.html)

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Literature review current through: Oct 2014. | This topic last updated: Sep 9, 2014.
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