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In late June 2018, 21 people living northeast Denver, Colorado, began receiving treatment following possible exposure to rabies.
A woman had taken an abandoned baby raccoon into her home and 20 people visited the home and may have come in contact with the raccoon’s saliva. Later, she contacted a wildlife animal rehab center hoping the staff could rehabilitate the baby raccoon. The center couldn’t accept the baby raccoon and its staff contacted the Weld County Health Department. The Health Department staff called the woman and asked if it could be tested for rabies. It was. The raccoon had rabies.1
These 21 Coloradoans were certainly not alone in being treated for rabies in the United States, though.
The U.S. Department of Health’s Centers for Disease Control and Prevention (CDC) estimates between 30,000 to 60,000 people receive post-rabies exposure treatment annually in the United States. 2
What is Rabies?
Rabies is a virus in the genus Lyssavirus. It is carried in the saliva and nerve and brain tissues of infected bats, dogs, raccoons, skunks, cats, and other land mammals. Occasionally, horses, cows, and other livestock may also be infected with rabies too.2
CDC reports distinct rabies virus variants (different kind of rabies) in dogs, bats, foxes, skunks, mongooses, and raccoons. These species are also rabies reservoirs. 2 While the scientific definition of “reservoir” is complex, think of the reservoirs of rabies as wildlife populations where rabies outbreaks occur.
That said, the different rabies variants can infect other species—a cross-over, in medical terms. For example, a rabid skunk could infect a horse.
Unvaccinated domestic dogs and cats, bats, wild raccoons, skunks, foxes, and mongooses are the leading carriers of rabies.
How Are Humans Infected?
Humans can be infected by being bitten by a rabid animal or exposed to an infected animal’s saliva, or nerve or brain tissue. 2
When a rabid mammal bites or scratches a person the rabid animal’s salvia transfers the virus into the person being bitten. The virus can also be transferred when a person touches or picks up a live rabid animal or a dead animal that had rabies.
The incubation period—the time between exposure and when the symptoms appear ranges from days up to months. Once infected, the rabies virus moves through the human’s nervous system to the brain. In the brain, the rabies virus causes inflammation—encephalitis in medical terms. 2
Rabies symptoms in humans can vary. Early symptoms may include fever, headache, and general weakness. Rabies can take either the “furious rabies” form or “dumb or paralytic rabies” form. In furious rabies, which is about 80% of the cases reported, later symptoms include insomnia, anxiety, confusion, slight or partial paralysis, hallucinations, increased saliva, trouble swallowing, and fear of water (hydrophobia) before death occurs. Dumb or paralytic rabies symptoms may start with tingling at the bite site followed by numbness, sudden weakness or paralysis. 3
Once later symptoms occur, death usually follows within days.
Rabies is almost always fatal.
How Common Are Rabies Cases?
In the United States, rabies control programs have greatly reduced the number of humans dying from rabies. In North American in the 1900s, the number of human rabies cases was estimated at 100 or more per year. By the 1990s fewer than 25 died from rabies each decade. 4
The CDC reports 1 to 3 human rabies deaths are reported in the United States annually. Between 2008 and 2017, the CDC reported 15 cases of people infected in the United States. Thirteen people died. Of these 10 people were infected (either bites or contact) by bats, two were infected by raccoons, and one was infected by a kidney transplant. An eight-year-old girl and a 17-year-old boy survived rabies following experimental medical treatments. 4 An additional eight people were infected (usually by dog bites) outside of the United States, returned to the United States and then died.
Why Have the Number of Rabies Cases Dropped in the United States?
Many state and local government agencies require rabies vaccination of pets, such as dogs, cats, and ferrets. Further, federal and state government agencies provide programs to control rabies by vaccinating wildlife populations. Upcoming blogs will explain more about rabies.
What do you do if you may have been exposed to rabies?
Don’t delay! The CDC recommends you5
- Consider any possible exposure a medical urgency.
- Immediately wash the wound or scratch with soap and water.
- Call your doctor.
For more details, see the CDC Website on rabies:
https://www.cdc.gov/rabies/exposurel
- https://www.cdc.gov/rabies/exposure/index.html
The current treatment for people exposed to rabies consists of the rabies immune globulin shot, followed by four shots of a rabies vaccine over a two-week period. For adults, the relatively painless vaccine shots are given in the upper arm. For children, the shots are given in the thigh.
Notes & Resources
1 Weld County Department of Health. (2018). 21 People Exposed to Rabies in Weld County. News release July 2, 2018. Weld County Department of Health. 1555 North 17th Street, Greeley, Colorado 80631. www.weldhealth.org Retrieved 23 December 2018.
Note that rabies is carried in the saliva of rabid (infected) animals. The rehab center had a general policy not to accept wildlife that are rabies reservoir. Rabies reservoirs differ across the United States. For more information, see CDC’s website Wildlife for Reservoirs for Rabies https://www.cdc.gov/rabies/exposure/animals/wildlife_reservoirs.html
2 Centers for Disease Control and Prevention. (2018) Human Rabies. Centers for Disease Control and Prevention. Retrieved from https://www.cdc.gov/rabies/ Retrieved 23 December 2018.
Center for Food Security and Public Health. (2012). Rabies and Rabies-related Lyssaviruses. Fact Sheet. Last updated November 2012. College of Veterinary Medicine. Iowa State University. Ames, Iowa, 50011. Retrieved from http://www.cfsph.iastate.edu/Factsheets/pdfs/rabies.pdf Retrieved 23 December 2018.
3 Centers for Disease Control and Prevention. (2018). Human Rabies. Centers for Disease Control and Prevention. Retrieved from https://www.cdc.gov/rabies/ Retrieved 23 December 2018.
World Health Organization. Rabies. Fact Sheet. Retrieved from https://www.who.int/rabies/about/home_symptoms/en/ 23 December 2018.
4 Centers for Disease Control and Prevention. (2018). Human Rabies. Centers for Disease Control and Prevention. Retrieved from https://www.cdc.gov/rabies/location/usa/surveillance/human_rabies.html Retrieved 9 January 2019.
5 Centers for Disease Control and Prevention. (2018). When should I seek medical attention? Fact Sheet. Centers for Disease Control and Prevention. Retrieved from https://www.cdc.gov/rabies/exposure/
CDC. What care will I receive? Fact Sheet. Centers for Disease Control and Prevention. Retrieved fromhttps://www.cdc.gov/rabies/medical_care. Retrieved 23 December 2018.
Up Coming Soon Blogs
How to Protect Yourself and Your Children from Rabies
A Closer Look at Rabies Vaccinations
The Untold Story of Rabies Management
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