Rabies is an infectious disease that can affect all species of warmblooded animals, including man. This disorder is transmitted by the saliva of an infected animal and is caused by a virus (Neurotropic lyssavirus) that affects the salivary glands and the central nervous system. The symptoms may lead to serious complications if the virus is not treated immediately.
The symptoms of rabies usually develop within 20-60 days after a bite or scratch from an animal infected with the rabies virus. The incubation period is the time between the exposure and the appearance of the first neurologic symptoms. The incubation period is usually shorter when the sight of exposure is closer to the brain. The initial symptoms may be a general feeling of discomfort or uneasiness, nervousness, anxiety, insomnia, depression, loss of appetite, fever, chills, cough, sore throat, headache, nausea, vomiting, and pain at the site of exposure. Serious neurological symptoms usually present themselves two to ten days after the initial symptoms. There are two types of syndromes that may develop during this neurological period: furious and/or paralytic (sluggishness and early paralysis).
The hyperactive or “furious” syndrome is usually characterized by thrashing, agitation, biting, spasms of the pharynx and larynx, choking, gagging, fear of water (hydrophobia), hyperventilation (very rapid breathing), and an alteration in the rhythm of the heart beat (cardiac arrhythmias). In about twenty percent of the patients a “paralytic” syndrome may occur. This syndrome is characterized by paralysis that starts at the bottom of a limb and moves upward (especially in the extremity that has been bitten), increased blood pressure, rapid heart rate, confusion, hallucinations and disorientation. During this time the patient may have increased periods of hyperactivity, stiffness in the back of the neck, and an abnormal increase in the number of cells in the cerebrospinal fluid ending with the onset of coma or respiratory failure.
Rabies is caused by a lyssavirus (a form of virus that causes encephalitis) that affects the saliva and nervous system. Most cases of rabies in humans are caused by a bite or scratch from an infected animal. It is possible, but rare, for people to get rabies if infectious material from a rabid animal, such as saliva, gets directly into their eyes, nose, mouth, or a wound.
At least two known cases of rabies has been contracted by breathing the air in caves where there were a large number of infected bats. There have also been a few recorded cases of rabies acquired by humans after cornea transplants from donors who had undiagnosed rabies.
Any mammal can get rabies. Wild animals typically thought to be carriers include raccoons, skunks, bats, foxes, and coyotes. Dogs, cats, and cattle are among the domestical animals that may develop rabies in the United States.
Rabies in humans has been almost completely eliminated in most developed countries. The vaccinations of domesticated animals and elimination of stray dogs has helped control this problem. In the 1980’s the U.S. Centers for Disease Control had one case per year reported. In the United States rabies is found primarily among wild animals such as skunks, foxes, bats, and raccoons. There were 49 cases of human rabies reported in the U.S. between 1960 and 1986. Only 7 of the 49 cases were acquired by exposure to rabid domesticated animals. The remainder were from wild animals.
Medical assistance should be obtained as soon as possible after an exposure or possible exposure to rabies. The most effective treatment for rabies is immediate treatment of the wound followed by immunization with the rabies vaccine. The wound should be cleansed thoroughly with soap and water and medical attention sought immediately. If the wound has broken the skin, a tetanus shot should be given. If the patient has been bitten by a wild animal that has escaped, or a domestic animal that shows signs of rabies, a series of vaccinations to prevent rabies is prescribed before the onset of symptoms. Once the disease presents itself in the patient there is no effective treatment to stop the progression.
In the United States, there have been no cases in which an individual developed rabies after treatment with the vaccine. Specific medical attention for someone exposed to rabies is called postexposure prophylaxis (PEP). This involves one dose of immune globulin and five doses of rabies vaccine over a 28-day period. Rabies immune globulin and the first dose of rabies vaccine should be given by a health car eprovider as soon as possible after exposure. For additional information related to treatment, contact the Centers for Disease Prevention and Treatment listed in the Resources section of this report or go to www.cdc.gov.
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