Contrary to popular belief, few parasites and diseases of insectivorous bats (those bats that eat only insects) pose any threat to human health.
- When bats inhabit a building, they pose little threat to the safety of people or other animals.
- Their nocturnal habit of feeding on insects means they seldom interact with humans.
- There are few valid accounts of bats attacking people. Even rabid bats rarely become aggressive.
Some diseases of potential concern are discussed below:
Histoplasmosis is a very rare respiratory disease in humans caused by a fungus that grows well in soils enriched with animal droppings.
In North America human cases are known primarily from the humid areas in the Mississippi and St Lawrence river valleys in association with accumulated guano of pigeons, starlings, and bats. However, the fungus requires ongoing warm, moist conditions and is rarely found in Alberta. There is only one report of the fungus in the province.
In 2003 a cluster of four human cases was documented in the Edmonton area. All individuals worked together on a golf course and were involved in a project to replace some sod. The sod originally came from British Columbia. Apparently there were fungus spores either in the sod or in the ground where the new sod was lain.
Rabies is an acute infectious disease of the central nervous system. It has been identified in a few bat species throughout Canada and the United States. In Alberta, testing of bats for rabies over many years indicate that the infection rate in bats is extremely low across the province.
It should be noted, however, that much information about rabies has been sensationalized and misrepresented. While individual bats should be handled cautiously, widespread fear and persecution of bats is unwarranted.
A summary of what is known about rabies in insectivorous bats can be found at:
Rabies Risk and Prevention
Alberta Bat-Related Rabies Infection Cases
Rabies is an extremely rare disease in Alberta. Since 1985, there have been two cases of human rabies in Alberta. Both occurred following bat exposures where the exposed person did not seek medical attention for preventative treatment following exposure to the bat.
- In July 1985, a man apparently contracted rabies from a big brown bat in northern Alberta. He did not seek treatment and did not receive rabies preventative vaccine before or after the exposure. In December 1985, the man died of the disease.
- In 2007, a case of bat-related rabies occurred in central Alberta. Similar to the first case, the initial encounter with a bat was not reported to a health care provider and the person later died from the infection.
What to do if you or your pet have had physical contact with a bat
Like most wild animals, biting is a natural defensive reaction for bats whenever they are confined or feel threatened. Avoid physical contact with live bats whenever possible.
If a person is bitten or scratched by a bat, the wound should be washed immediately and medical assistance should be sought.
Any bat that may have exposed someone to rabies should be captured for testing if possible. If you are certain there was no possible rabies exposure, then the bat should be left alone, or returned to the wild.
To capture a bat:
- Find a small container like a box or a large can, and a piece of cardboard large enough to cover the opening in the container. Punch small air holes in the cardboard.
- Put on leather work gloves and if available, a safety mask/goggles or face shield.
- When the bat lands, approach it slowly and place the container over it. Slide the cardboard under the container to trap the bat inside.
- If you are certain there’s been no contact between the bat and any people or pets, carefully hold the cardboard over the container and take the bat outdoors and release it into the air (not onto the ground) away from people and pets.
If there is any question about contact between the bat and people or pets, save the bat for testing. Tape the cardboard to the container, securing the bat inside. For potentially exposed persons, contact a local public health office for follow-up, or seek medical attention immediately. Contact a veterinarian to seek treatment for any exposed pets. The local public health office or the veterinarian will coordinate testing of the bat if warranted.
The following are web sites with additional information:
- Alberta Office of the Chief Veterinarian rabies information landing page
- Bats and Rabies, A Public Health Guide – Bat Conservation International brochure
An effective rabies vaccine is available to prevent the disease in humans and is effective for both pre-exposure and post-exposure prophylaxis. Rabies is nearly 100 per cent preventable if timely treatment is sought following a rabies exposure.
For more information on the rabies vaccine for humans see MyHealth.Alberta.ca.
Ectoparasites (Bat bugs)
Ectoparasites, primarily bat bugs (Cimicidae), that live on bats only try to bite people if there are no bats to feed on (i.e., AFTER control measures to eliminate bats have been taken).
Bat bugs rarely feed on humans in Alberta and, while an annoyance, they are not considered dangerous since they are not known to transmit any diseases.