Rabies is a viral infection of the nervous system. It is mainly a disease of wild animals, but humans can get it through bites from infected animals.
Human rabies is very rare in the United States. Since 1990, there have been only 55 diagnosed cases. However, rabies is far more common in other parts of the world. Worldwide, there are about 40,000 to 70,000 rabies-related deaths each year. The majority of these cases are caused by bites from unvaccinated dogs.
Only mammals can get rabies. In Virginia, it is transmitted most commonly in bats, skunks, foxes, raccoons, dogs, cats and some farm animals. Rabbits, squirrels, rats, mice and small pets such as gerbils and hamsters seldom get it.
The rabies virus is neurotropic. This means it moves within the nerves of the body. The virus is introduced through the bite of an infected animal. Virus concentrations are very high within the saliva of the infected mammal. The virus then travels through the peripheral nerves to the central nervous system and brain. Depending on the distance of the bite wound from the brain, the incubation period of the disease can be one to three months.
Initial symptoms of rabies infection are non-specific and flu-like: general malaise, headache and fever. There is usually a change in sensation around the bite wound. As the disease progresses, the central nervous system becomes hyper-excitable. The slightest touch is painful and muscle movements are exaggerated, eventually leading to convulsions.
With time, symptoms expand to include anxiety, insomnia, confusion, agitation, abnormal mental behavior, hallucinations, delirium and paralysis. Large quantities of saliva and tears are produced. This, in conjunction with difficulty swallowing due to paralysis of the jaw and throat muscles, leads to a fear of drinking liquids (hydrophobia) and “foaming” at the mouth. Death results from respiratory center failure.
Rabies infection in humans is almost always fatal. That is why it is so important for those at risk for rabies exposure to be vaccinated for pets to be vaccinated, and for those who have been bitten by an animal to be treated immediately.
Rabies vaccine is given to people at high risk of rabies to protect them if they are exposed. These include veterinarians, animal handlers, rabies lab workers, spelunkers, international travelers and rabies biological production workers. The vaccine can also prevent the disease if it is given to a person after they have been exposed.
Between 16,000 and 39,000 people are vaccinated each year as a precaution after animal bites. If you get bit by an animal, wash the wound thoroughly with soap and warm water. Contact your doctor immediately. The local animal control and health departments should also be notified.
Also, keep your pet’s vaccinations up to date. Keep your animals on your property; don’t let them roam free. Don’t leave garbage or pet food outside, as it may attract wild or stray animals. Enjoy wild animals from a distance. Don’t keep wild animals as pets. If you see an animal acting strangely, report it to your local animal control department and don’t go near it.
The content in this column is for informational purposes only. Consult your physician for appropriate individual treatment. Dr. Reynolds practices Family Medicine in Chesterfield.