Rabies

Rabies
Definition
Rabies is a viral infection of the central nervous system. Rabies is almost always fatal unless treated before symptoms appear.
The Nervous System

Causes
A virus found in infected, warm-blooded animals causes rabies. Animals in the U.S. that commonly carry the virus include:
• Bats
• Raccoons
• Skunks
• Foxes
• Coyotes
The rabies virus is present in the saliva, brain, or nerve tissue of infected animals. Usually, humans contract rabies through a bite or scratch from an infected animal. The virus may also be transmitted if infected tissue comes into contact with human mucous membranes, such as in the eyes, nose, or mouth.
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition. The only risk factor for contracting rabies is contact with an infected animal. In most parts of the U.S. any contact with a bat may be considered a rabies risk factor. Seek medical advice if you find a bat anywhere inside your home.
Symptoms
After exposure, the rabies virus may incubate for 10 days to one or more years in humans before symptoms appear. Usually symptoms develop within 3-7 weeks, after which treatment will not stall the progression of the infection. Death usually occurs within a week after symptoms appear.
Symptoms in humans may include:
• Pain, tingling, or itching at the site of the bite wound or other site of viral entry
• Stiff muscles
• Increased production of thick saliva
• Flu-like symptoms, such as headache, fever, fatigue, nausea
• Painful spasms and contractions of the throat when exposed to water (called "hydrophobia")
• Erratic, excited, or bizarre behavior
• Paralysis
Symptoms in animals may include:
• Erratic behavior (often overly aggressive or vicious)
• Disorientation (e.g., nocturnal animal such as a bat or fox appearing in daylight)
Diagnosis
If you think you have been exposed to rabies, see a doctor or contact a public health official immediately.
If the animal is available and appears well, it will be kept under observation for 7-10 days. If no symptoms develop, you are not at risk for rabies. If the animal is sick or dead, it's head will be shipped to a special facility where its brain will be examined for the presence of the virus. In the meantime, you may be advised to begin treatment.
If the animal is unavailable, treatment may often be recommended depending on the animal's species, where the encounter took place, and other factors.
Treatment
If an animal has bitten you, immediately do the following:
• Wash the wound immediately with plenty of soap and water to remove saliva; this is the most important first step you can take in preventing rabies
• Call your doctor or seek care in an emergency room
If it is likely that you have been exposed to rabies, your doctor will recommend post-exposure prophylaxis. This involves two injections:
Human Rabies Immune Globulin (HRIG)
This should ideally be given within 24 hours after exposure. It contains large quantities of antibodies to the rabies virus. In most cases, half of the dose should be injected into the wound and surrounding tissue. The remainder is given intramuscularly. If you have previously received rabies vaccine, you may not need the HRIG shot.
Other Rabies Vaccines
Unlike the HRIG, rabies vaccines cause your own immune system to develop protective antibodies against the rabies virus. These antibodies will live in your body for many years. There are three types of rabies vaccines available:
• Human diploid cell vaccine (HDCV)
• Rabies vaccine adsorbed (RVA)
• Purified chick embryo cell culture (PCEC)
Over the next four weeks, your doctor will give you five shots of one of these vaccines. The vaccine will be injected into your upper arm muscles.
Certain medications may interfere with your body's response to the rabies vaccine. Be sure to tell your doctor about all medications or herbs that you take on a regular basis.
Prevention
To help prevent rabies:
• Vaccinate house pets.
• Avoid contact with wild animals.
• Do not touch any wild animal, even if it appears to be dead.
• Seal basement, porch, and attic openings to prevent an animal from entering your home.
• Report any animal to your local animal control authorities that is acting strangely or appears sick.
• If you regularly come in contact with animals, have the rabies vaccine prior to any exposure to rabies (preexposure prophylaxis). Booster doses are often required.