Rabies reservoirs in the United States

What is Rabies?

Rabies is a fatal viral infection that affects the central nervous system. All mammals, including man, can get rabies. The disease is spread by infected animals, usually through bites, but scratches and saliva contact with broken skin are also possible routes of infection.

What are the symptoms of Rabies?

After an animal has been infected with the virus, and depending upon what animal it is, a few days to several months may pass before signs of the disease show up (incubation period). Two different forms of rabies are possible. In the furious form, the animal is excited, aggressive, irritable, and may snap at anything in its path. It loses all caution and fear of natural enemies. If the animal has the dumb form of the disease, it may appear unusually tame, affectionate and friendly. Staggering, paralysis, and frothing at the mouth are sometimes noticed. Many animals have a change in the sound of their voice.

In humans, the course is similar. After a symptom-free incubation period that ranges from 10 days to a year or longer (the average is 30 to 50 days), the patient complains of malaise, loss of appetite, fatigue, headache, and fever. Over half of all patients have pain (sometimes itching) or numbness at the site of exposure. They may complain of insomnia or depression.

Two to 10 days later, signs of nervous system damage appear, hyperactivity and hypersensitivity, disorientation, hallucinations, seizures, and paralysis. Death may be sudden, due to cardiac or respiratory arrest, or follow a period of being comatose that can last for months with the aid of life-support measures.

How do people and animals get Rabies?

Since rabies virus lives in the saliva of rabid animals, a bite is the most common way the disease is transmitted. People may also become exposed to rabies by being scratched by a rabid animal or if saliva gets into an open wound on the skin, and saliva contact with mucous membranes of the eyes, nose or mouth.

There is no danger from touching or petting a rabid animal unless saliva from that animal gets into an open wound, or your eyes, nose or mouth. Just being in the same room or in the same vicinity as an animal with rabies does not result in exposure.

How common is Rabies?

Over the last 100 years, rabies in the United States has changed dramatically. More than 90% of all animal cases reported annually to CDC now occur in wildlife; before 1960 the majority were in domestic animals. The principal rabies hosts today are wild carnivores and bats. The number of rabies-related human deaths in the United States has declined from more than 100 annually at the turn of the century to one or two per year in the1990's. Modern day prophylaxis has proven nearly 100% successful. In the United States, human fatalities associated with rabies occur in people who fail to seek medical assistance, usually because they were unaware of their exposure.

Rabies control programs in the United States have made rabies occurance in humans and domestic animals a rare event. Although rabies is relatively rare in the United States, the importance of rabies prevention should not be underestimated. Esitmates of human rabies deaths worldwide have been set as high as 50,000. Developing countries without proper rabies control programs suffer from rabies epidemics. In many of these areas rabies occurs in high incidence among animals (especially dogs) that commonly interact with human populations. This results in a high number of human transmissions and deaths due to the lack of preventative and treatment programs.