One summer morning, a Colorado woman found a bat in her house, hanging behind a curtain. Intending to return the bat outdoors, she captured it in her hands and was bitten. She dropped the bat, which flew out the door and disappeared. The woman was treated for possible rabies exposure.
An 11-year-old girl also underwent rabies shots after she had attempted to rescue what she thought was a bird from the family cat. When she started to remove the "bird," it bit her on the finger. This bat was captured and tested positive for rabies.
These are recent examples of documented cases where people have encountered bats in Colorado. In each example, the bats exhibited warning signs that something was wrong.
Overall, most bats that inhabit our state are healthy, and the ones you see flying around at night probably aren't rabid. According to Bat Conservation International, "Bat rabies accounts for approximately one human death per year in the United States. Thus, some people consider bats to be dangerous."
"To put the rate in perspective," Merlin Tuttle, an active member of Bat Conservation International (BCI), states, "bicycle accidents killed 800 people, bee stings 95, and dog attacks 20 in the most recent year of reporting for the United States alone. Due to successful dog and cat vaccination programs, rabies is now the second rarest disease in the United States and Canada, behind polio." Clearly, bats do not rank very high among mortality threats to humans. Nevertheless, prudence and simple precautions can save lives.
The Colorado Parks and Wildlife and the Colorado Department of Public Health and Environment want to inform you about rabies in bats: what suspicious behavior to look for, what to do if you find a bat or are exposed to one, and how to prevent encounters with bats.
Bats in Colorado
- There are 18 species of bats known to live in Colorado.
- Some are here year-round, and some migrate through the state.
- They can be found in every habitat—from the eastern plains to the high mountain forests and western deserts, from rural Colorado to downtown Denver.
- All of our bats eat insects; they play a valuable role in ecosystems by helping to control insect populations.
- Little brown bats, for example, have been known to catch and eat more than 150 mosquitoes and crop pests in less than 15 minutes. Bats also pollinate plants and crops.
Many bats roost in roofs, attics and sheds, without people knowing the bats are there. When people remodel, for example, a roost may be discovered and the bats might then be excluded. There are certain times of the year when it is better to exclude bats. If you need information on excluding bats from your home, call your Parks and Wildlife office. An excluded bat might find a temporary roost site, but the site might be visible to people. Although daytime activity can be a sign of rabies, not all bats roosting visibly have rabies. If left undisturbed, the bat will probably leave in the evening to find a more suitable roost site.
Juvenile bats may also temporarily roost in a visible place. These bats are learning to fly, to eat on their own, to find drinking sources, and to find a roost site. As with many young animals starting out on their own, some juvenile bats die during this period. A bat that is seen during the day does not necessarily have rabies, but be cautious. It might have the disease or it might be injured. The bat may have also been recently excluded from its roost or it may be a lost juvenile.
Bats roost in trees, mines, caves and attics, or under rocks, roofs and siding. If you see one in an unusual place, such as on the side of a building or on the ground, beware. Bats also have remarkably accurate control of their flight, so another red flag is a bat that can't fly and repeatedly crashes into things. A good rule of thumb: if a bat is acting abnormally, the chances are it is sick. Bats that have contact with people, that children find, or pets capture are usually sick or injured and pose a greater risk of being rabid.
Rabies is a virus that affects the central nervous system of mammals, causing a fatal inflammation of the brain and spinal cord. Rabies virus is shed in the saliva of an infected animal and is transmitted mainly through bites. It is also possible to get the virus through the introduction of saliva to open wounds, cuts or mucous membranes, like eyes, nose and mouth. "Symptoms most often develop about 10 days to seven months after infection, and death follows 2-12 days later," according to Bat Conservation International.
Rabies in Bats and Wildlife
Five species of wildlife are the main hosts of rabies in the U.S., in this order:
In Colorado, bats have been the primary rabies host for the past 20 years. Between 1977 and 1996, 685 of the 697 animals (98 percent) that tested positive for rabies were bats.
Since 1977, Colorado has recorded only 12 cases of rabies in species other than bats:
Three of the skunks, the fox and cat had been infected by a bat. However, in the time period January 2007 through April 2010 there has been a significant increase in non bat rabies:
3 red fox
1 mountain lion
2 domestic cats
The percentage of bats testing positive for rabies has averaged 15.2 percent. Statistics from Bat Conservation International show, "Worldwide, more than 30,000 humans die of rabies each year, 99% of cases resulting from contact with dogs. In the United States, due to highly successful dog vaccination programs, transmission from dogs is now rare, eliminating the vast majority of human cases."
It's important to point out that this percentage reflects only bats found by people and submitted for testing. It's not a representative sample of all bats in Colorado. Studies have suggested that less than 1 percent of all bats may be infected.
Some Warning Signs
As the disease progresses, animals lose muscle control and coordination, stop eating and drinking and show signs of paralysis.
According to BCI, "Rabies is often referred to as hydrophobia because victims fear swallowing. Drinking or eating can bring on muscle spasms of the throat. The fear of swallowing also accounts for saliva accumulation referred to as 'foaming' at the mouth. Infected animals may be either agitated and aggressive or paralyzed and passive. Dogs, cats, and other carnivores often become aggressive and try to attack humans and other animals, but bats are typically passive. Bats normally bite only in self-defense if handled, and aggressive behavior is rare, even when rabid."
"Early symptoms in humans include pain, burning, and numbness at the site of infection. Victims complain of headaches, inability to sleep, irritability, muscle spasms of the throat and difficulty swallowing. Convulsions may occur, followed by unconsciousness and death."
John Pape, Colorado State Health Department Epidemiologist, who specializes in animal-related diseases, explains that bats are an important part of the ecosystem because they eat mosquitoes and other insects and pollinate plants. "Bats should not be killed indiscriminately or because of a fear of rabies," Pape said. During migration time, finding a bat hanging under the eave of a house, under a porch over-hang, hidden behind shutters or gutters or in a tree is normal. Just leave bats alone and usually they will leave on their own. Experience and studies have proven that killing bats or destroying their roosting sites won't eliminate rabies or reduce its occurrence in bat populations. Therefore, the best way to prevent being exposed to rabies is to take a few simple steps.
- Do not pick up or handle bats—or any wildlife for that matter. The most common ways people have been exposed to rabid bats are by picking one off the ground, trying to remove a bat from the house, taking a bat from a family pet and having a bat land on them. People also have awakened to find a bat in their bedroom or house, and when that happens, it can be difficult to determine if an exposure has occurred.
- Warn children to never handle an unfamiliar animal. If a bat or wild animal lets you approach or handle it, there's something wrong with the animal. In defense, most animals will bite.
- Keep pets currently vaccinated against rabies. Immunization has proved successful in controlling rabies in domestic dogs and cats. The last rabid dog was reported from El Paso County in 1974, the last domestic cat from Grand County in 1985. Wildlife obviously isn't vaccinated for rabies, although experimental oral rabies vaccines are being tested for species such as raccoons and skunks. As for bats, there is no effective way to control or prevent rabies in their populations.
- Keeping your pets vaccinated protects them from exposures to rabies, including exposures you may not be aware of, such as a cat catching and eating a bat. If exposed to rabies, an unvaccinated pet must be quarantined, which can be expensive.
- Keep bats out of your home. Contact Parks and Wildlife, or the Colorado Department of Health for more information on non-lethal methods to remove bats from your attic or house, as well as ways to bat-proof your residence.
What to do if You Encounter an Injured or Sick Bat
- Never handle a bat with your bare hands! If your pet catches a bat or you find one in your house, make a reasonable attempt to capture the animal, but take precautions so you're not bitten or scratched. Avoid damaging the bat.
- Wear heavy gloves or use tongs or a shovel to pick up the bat. Confine it in a container, such as a coffee can. Slide cardboard under the can and tape it closed.
- Contact your local health department or animal control agency to report the incident. These agencies can determine if the bat can be released or should be tested.
- If your pet was bitten by a bat, had a bat in its mouth or was near a grounded bat, also contact your veterinarian.
What to do if a Bat Encounters You!
- If you are bitten or scratched by a bat, report immediately to a family physician or public health professional for evaluation as a possible rabies exposure. Clean the area with soap and water and apply alcohol or iodine. Bat teeth are small and very sharp, so the wound may be no more than a pin-like puncture, or may not be visible at all.
- You may not see a wound or mark, but if you think you may have been bitten or can't eliminate the possibility (e.g., awake to find a bat in your bedroom), seek medical attention immediately. Contact the local health department to arrange for the bat to be tested.
- If the bat is not recovered or it tests positive for rabies, you will need preventative treatment immediately. Rabies shots aren't nearly as traumatic as in the past. Today, fewer shots are required and they are administered in the arm and buttocks, rather than the stomach.
- People who are at increased risk of exposure because they handle wildlife, such as rabies researchers, field biologists, and animal rehabilitators, should receive pre-exposure vaccinations.
Bats are fascinating wildlife neighbors and important components of the native ecosystems of wild Colorado. However, bats can transmit rabies to people, and unfortunately, the incapacitated bats that come in contact with people are those most likely to have the disease.
With a little knowledge, caution and respect for the wild in wildlife, bats and people can coexist in Colorado.
For More Information
(Answers to frequently asked questions about bats can be found in the FAQ section. Go to the FAQs page; from the "Topic" drop-down list, choose "Co-existing with wildlife"; select "Bats" as the subtopic; click on the "go" button.)
Colorado Parks and Wildlife
1313 Sherman Street, 6th Floor
Denver, CO 80203
303-297-1192 (Mon-Fri 8 a.m. - 5 p.m. MST, except state holidays)
Submit a question to AskCPW.
Colorado Dept. of Public Health and Environment
Disease Control and Environmental Epidemiology Division
4300 Cherry Creek Drive South
Denver, CO 80222
Colorado Bat Society
1085 14th St. Suite 1337
Boulder, CO 80302
To learn more about bats or volunteer to help bats, check out the Bat Conservation International website.