Over the last 100 years, rabies in the United States has changed dramatically. More than 90% of all animal cases reported annually to the Centers for Disease Control (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 the 1990s.
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. The revised human rabies prevention recommendations of the Advisory Committee on Immunization Practices describing the use of a reduced (4 dose) vaccine schedule for postexposure prophylaxis to prevent human rabies is now available. Read more about it on the CDC website. These recommendations update the 2008 recommendations and inform about the following:
- Present cost-effectiveness of rabies postexposure prophylaxis
- Present recommendations for rabies pre- and post-exposure prophylaxis
- Provide updated information on human and animal rabies epidemiology
- Summarize the evidence regarding the effectiveness, immunogenicity, and safety of rabies biologics
Misinformation Leads to Anxiety
Throughout human history, few illnesses have provoked as much anxiety as has rabies. Known as a distinct entity since at least 500 B.C., rabies has been the subject of myths and legends across time and cultures. And while the incidence of human cases in the U.S. has declined markedly over several decades, rabies continues to inspire dread today. Amidst this concern is a great deal of misinformation about the disease.
Rabies (or hydrophobia), is a viral disease transmitted via the bite of an infected (rabid) animal or by its lick over an open cut. The rabies virus is present in the infected animal's saliva. After a person is bitten by an infected animal, the virus multiplies at the bite site, and then travels along nerves to the brain.
Once in the human brain, inflammation causes delirium, painful muscle spasms in the throat, and usually death. Pet vaccination programs and prompt treatment of animal bites has reduced the number of rabies cases in the United States to 5 per year. There are an estimated 65,000 human rabies cases each year throughout the world.
The incubation period ranges from 10 days to more than a year, depending on the entry site. Rabies infection characteristically produces a rapidly progressive encephalomyelitis (inflammation of the brain and spinal cord), and should be considered as a possible cause of any such illness in humans or other animals. The early symptoms are fever, headache, and loss of appetite which are nonspecific. After a while the patient becomes restless and disoriented and may experience seizures. The term hydrophobia (Greek for "fear of water") comes from the patient's failed attempts to satisfy a characteristic thirst because painful throat spasms prevent swallowing. Coma and death usually follow 3 to 20 days after the onset of symptoms.
Once symptoms have appeared, treatment is limited to sedatives and painkillers. Few people with rabies have survived. If a bite has occurred and there is a risk of rabies, patients are passively immunized with antirabies serum followed by a series of rabies vaccinations. If this routine is begun within two days of the bite, rabies is usually prevented. An animal suspected of being rabid is killed.
Vaccinations for Handlers
Veterinarians, animal handlers, some laboratory workers, and persons visiting countries where rabies is a constant threat are routinely vaccinated with an inactivated form of the rabies virus.
Rabies in Animals
Rabies is primarily a disease of non-human animals. It appears that any mammal species can develop rabies. The prevalence of rabies in specific animal species varies greatly by geographical region. Knowing which animals are most likely to be rabid in a given location is essential to implementing appropriate preventive and postexposure measures.