Bats and Rabies

Agency: Community Health

Bats are a beneficial species.  They are an important part of any local ecosystem, with some species eating significant numbers of potential agricultural pests such as beetles and moths.  Bats are often toted by bat conservation groups as natural mosquito control agents, but in reality, bats probably do not play a significant role in the control of mosquito populations.  Mosquitoes represent a meager meal for most bat species, and since mosquitoes prefer the cover of foliage, are not readily available to hunting bats.  While the conservation message is a good one, and bats are a protected species in Michigan, bats can carry rabies and are a significant source of potential rabies exposure for humans in the United States.  Although human rabies cases are rare in the U.S., with an average of 2-3 cases documented each year, the vast majority of these cases in recent years have been caused by strains of rabies virus associated with bats.  It is estimated that in the U.S., 40,000 people each year receive rabies post-exposure prophylaxis (PEP ), many of these following an exposure to bats.  Some of these treatments can be avoided if the bat can be collected and tested for rabies.  If the animal tests negative for rabies, no treatment is necessary.

Bats are the animal most often found to be rabid in Michigan.  Rabies has been detected in bats throughout the state.  In general, the rate of rabies in the general populations of bats is thought to be less than 1%.  An average of 6% of the bats tested at the Michigan Department of Community Health's Bureau of Laboratories are positive for rabies.  The reason for the difference is the bats that get submitted for testing are more likely to be sick bats that are behaving abnormally and are therefore found inside the home or are caught by pets.

In many of the human rabies cases caused by a bat-stain of the virus, there was no known history of a bite from a bat.  For that reason, bats represent a special concern.  Bats have very small teeth, and a bite from a bat may not be felt.  Any direct contact with a bat represents a potential exposure to rabies.  Other situations that might qualify as exposures include finding a bat in the same room as a person who may not be aware that contact has occurred, such as finding a bat in the room with a sleeping person, a child, or someone who is mentally disabled or intoxicated.  If you think you may have been exposed to rabies from a bat, please DO NOT LET THE BAT GO.  In these instances, you should safely collect the bat until the need for rabies testing has been evaluated.  Wearing leather gloves, place a coffee can or box over the bat, then use a piece of cardboard with holes punched in it to slide under the can or box, taping this cover firmly to the container.  

Contact your local health department or animal control agency to discuss the need for testing.  The bat must be humanely euthanized before it is submitted for testing [See the following link for instructions on how to humanely euthanize a bat].  If the bat tests negative for the presence of rabies virus, then no treatment for the exposed person is required.  If the bat tests positive for rabies, or the bat is not available for testing then the exposed person should receive rabies PEP.  Rabies infection is preventable if treatment begins soon after exposure to the virus.  Contact your local health department for help in determining the need for rabies PEP.