Rabies (hydrophobia) is an acute central nervous system (CNS) infection. It usually is transmitted by an animal bite and is almost always fatal after symptoms occur. Fortunately, immunization that begins soon after infection may prevent fatal CNS invasion.
Increased domestic animal control and vaccination in the United States have reduced cases of rabies in humans. Consequently, most human rabies can be traced to dog bites that occurred in the other counteries or bites from wild animals, such as raccoons.
Most often rabies transmission occurs through the bite of a rabid animal. Rarely, people contract rabies when saliva from an infected animal comes in contact with their eyes, nose, mouth or a wound. This may occur if you are licked by an infected animal.
Inhaling the rabies virus is another potential route of exposure, but one likely to affect only laboratory workers.
Petting a rabid animal or coming into contact with the blood, urine or feces of a rabid animal isn't considered an exposure to rabies and doesn't indicate a need for treatment.
Symptoms and Signs
Symptoms usually occur two to eight weeks after infection, but it can take two years or more for symptoms to appear. Early symptoms include fever, headache, malaise, numbness and tingling around the wound. Later, spasms, hallucinations, extreme thirst, hydrophobia, manic behaviour, paralysis and coma may develop.
No tests can confirm the rabies diagnosis in humans before onset. In the United States, the rapid fluorescent focus inhibition test (RFFIT) is the standard measure for rabies neutrality antibody. The results of this in vitro cell culture neutralization test are available within 24 hours. The Centers for Disease Control and Prevention considers complete neutralization at the 1:5 level by RFFIT an adequate antibody titer.
The rabies virus also may be isolated from certain infected tissue or secretions in animals or humans. Histologic examination of brain tissue from human rabies victims typically shows perivascular inflammation of the gray matter, neuronal degeneration, and characteristie cytoplasmic inclusion bodies (Negri bodies).
Immunization as soon as possible after exposure and meticulous wound care are the treatments for rabies.
Before performing wound care, remember to put on gloves to avoid contact with infected blood. Thoroughly wash all wounds and abrasions with soap and water. Check the patient's immunization status, and administer tetanus-diphtheria prophylaxis, if needed. Take measures to control bacterial infection as ordered. If the wound requires suturing, special techniques may be used to ensure proper wound drainage.
Although no specific drugs are available to treat rabies, postexposure prophylaxis usually is successful in preventing disease when used appropriately during the rabies incubation period. Treatment is mainly supportive, with special attention given to the cardiovascular and respiratory systems.
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