MSU Extension

Rabies is a viral disease that affects warm-blooded animals including humans. The infection, transmitted by saliva, travels via peripheral nerves to the brain, where it causes acute inflammation that generally results in death. Though the first documented case of rabies in the United States didn’t occur until 1768 in Boston, historically cases of rabies have been noted as early as 2000 B.C. Originating in the Old World, rabies is now in over 150 countries and all continents except Antarctica. Globally, between 26,000 and 55,000 people die annually as a result of rabies with over 95 percent of these deaths occurring in Asia and Africa.

Where dogs are the main source of rabies in much of the world, in the U.S. rabies is found primarily in bats, raccoons, skunks, and foxes. Bat bites are responsible for most human rabies infections with rabid bats now reported in all 48 contiguous states. Over the last 100 years, rabies in the U.S. has changed dramatically with 90 percent of documented animal cases now occurring in wildlife rather than domesticated animals such as pets and farm animals. During the same time period, the annual number of rabies-related human deaths in the U.S. dropped from over 100 at the turn of the century to one to two per year by the 1990’s.

A major reason for both these changes is regular vaccination of pets and other domesticated animals. The first rabies vaccine was developed in 1885 by Louis Pasteur and Emile Roux. Over the years, researchers have continued to create even more effective vaccines to protect both animals and people from this deadly disease. Human fatalities that do occur are likely due to the person not being aware that they have been exposed to the rabies virus and thus not seeking necessary medical intervention until the disease has progressed to a point where medical treatment cannot save them.

 In addition to vaccinating animals, it is strongly suggested that certain groups of people who are considered at risk for contracting rabies receive what is known as a pre-exposure rabies vaccination . Those at elevated risk include individuals who work with rabies in laboratory settings, veterinarians, animal control officers, wildlife workers, and travelers to countries where rabies is wide spread. The Centers for Disease Control and Prevention (CDC) offers guidelines explaining various risk levels and recommending precautionary actions. They do caution that pre-exposure vaccination will not prevent a person from contracting rabies if bitten but will decrease the number of doses of post-exposure vaccine and eliminate the need for receiving a rabies immune globulin injection.

If initiated with little or no delay, a series of injections given after a person has been exposed to the rabies virus, also known as post-exposure prophylaxis (PEP), is 100 percent effective in treating the rabies infection. If the bat or animal that has bitten or scratched a person cannot be captured and tested for rabies, it is recommended that the person start the post-exposure regimen as soon as possible, generally within six days. Unlike the earliest rabies injections, current vaccines are administered in your arm and no more painful than a flu or tetanus vaccine. If you awaken to find a bat in your bedroom or the bedroom of an infant, small child, or disabled adult, it is also highly recommended to administer PEP to that individual even if you are not certain they have actually been bitten. Delaying treatment until symptoms appear will likely mean certain death.

Initial symptoms are similar to having the flu: fever, headache, general feeling of weakness or discomfort. Some people also report an itching or prickling sensation around the site of the bite. As the disease progresses, a victim will exhibit anxiety, confusion, and agitation. Delirium, insomnia, and hallucinations may also occur. In the later stages, patients often experience partial paralysis, difficulty swallowing, and hypersalivation. Some individuals develop hydrophobia (fear of water), which historically is what rabies was often called. As a child you may have first learned about rabies while watching and sobbing your way through the classic movie Old Yeller. Once these acute symptoms have appeared, within two to ten days the victim generally suffers respiratory arrest and dies.

Unfortunately, rabies can only be definitively diagnosed after symptoms start when it may be too late to save the victim’s life. The length of time it takes for symptoms to present varies greatly. Typically symptoms begin to be exhibited between one to three months after exposure to the rabies virus but there are documented cases where symptoms began as early as four days and as late as six years after exposure.

Efforts are being conducted globally to raise awareness, provide education, and increase rabies prevention programs. Sept. 28, World Rabies Day, is an annual campaign that is now celebrated in many counties around the globe since it was first cosponsored by CDC and Global Alliance for Rabies Control in 2007. Michigan health officials, as well as those in many other states, offer precautions to reduce your risk of contracting rabies. Their suggestions include:

• Have all pets and domestic livestock especially dogs, cats, ferrets, horses, cattle, and sheep vaccinated by a licensed veterinarian and then maintain the recommended schedule of regular boosters.
• Do not let your pets wander or mingle with stray animals and only feed your pets indoors to discourage “visitors”.
• Never approach or handle an unfamiliar or wild animal and do not keep wild or exotic animals as pets.
• If bitten by an animal, wash the wound thoroughly with soap and water, then seek immediate medical attention to determine if you need PEP.

For more information about maintaining a healthy lifestyle and keeping your family, pets and other animals safe, visit Michigan State University Extension.