Rabies
Definition
Rabies is an often fatal viral infection primarily spread by infected animals.
Causes
Rabies is spread by infected saliva that enters the body through a bite or broken skin. The virus travels from the wound to the brain, where it causes swelling, called inflammation. This inflammation results in the symptoms of the disease. Most rabies deaths occur in children.
The actual time between infection and when you get sick (called the "incubation period") ranges from 10 days - 7 years. The average incubation period is 3 - 7 weeks.
In the past, human cases in the U.S. usually resulted from a dog bite, but recently, more cases of human rabies have been linked to raccoons or bats. Although dog bites are a common cause of rabies in developing countries, there have been no reports of rabies caused by dog bites in the U.S. for a number of years due to widespread animal vaccination.
Other wild animals that can spread the rabies virus include:
- Bats
- Foxes
- Raccoons
- Skunks
Very rarely, rabies has been transmitted without an actual bite. This is believed to have been caused by infected saliva that has gotten into the air.
The United Kingdom had once completely eradicated rabies, but recently, rabies-infected bats have been found in Scotland.
Symptoms
Exams and Tests
If an animal bites you, try to gather as much information about the animal as possible. Call your local animal control authorities to safely capture the animal. If rabies is suspected, the animal will be watched for signs of rabies.
A special test called immunofluorescence is used to look at the brain tissue after an animal is dead. This test can reveal whether or not the animal had rabies.
The same test can be used to check for rabies in humans, using a piece of skin from the neck. Doctors may also look for the rabies virus in your saliva or spinal fluid.
Treatment
Clean the wound well with soap and water, and seek professional medical help. You'll need a doctor to thoroughly clean the wound and remove any foreign objects (debridement). Most of the time, stitches should not be used for animal bite wounds.
If there is any risk of rabies, you will be given a preventive vaccine.
Outlook (Prognosis)
It's possible to prevent rabies if immunization is given within 2 days of the bite. To date, no one in the U.S. has developed rabies when given the vaccine promptly and appropriately.
Once the symptoms appear, few people survive the disease. Death from respiratory
failure usually occurs within 7 days after symptoms start.
Possible Complications
Untreated, rabies can lead to coma and death.
In rare cases, some people may have an allergic reaction to the rabies vaccine.
When to Contact a Medical Professional
Go to the emergency room or call the local emergency number (such as 911) if an animal bites you.
Prevention
To help prevent rabies:
- Avoid contact with animals you don't know.
- Get vaccinated if you work in a high-risk occupation or travel to countries with a high incidence of rabies.
- Vaccinate your dogs and cats by 4 months of age, followed by a booster shot one year later, and then another one every 1 or 3 years, depending on the type of vaccine used.
- Follow quarantine regulations on importing dogs and other mammals in disease-free countries.
References
Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice.
5th ed. St. Louis, Mo: Mosby; 2002:1837-1838.
Stantic-Pavlinic M. Public health concerns in bat rabies across Europe. Euro Surveill
. 2005 Nov 1;10(11) .
Brookes SM, Aegerter JN, Smith GC. European bat lyssavirus in Scottish bats. Emerg Infect Dis
. 2005 Apr;11(4):572-8.
Cohen J, Powderly WG. Infectious Diseases
. 2nd ed. New York, NY: Elsevier; 2004:1503-1506.
McLellan SL. Vaccine special issues: yellow fever, rabies, and Japanese encephalitis. Clin Fam Pract
. 2005;7:697-716.
Marx J. Rosen's Emergency Medicine: Concepts and Clinical Practice
. 6th ed. St. Louis, Mo: Mosby; 2006.
