Rabies in two big brown bats in Saskatchewan
The Canadian Wildlife Health Cooperative (CWHC), Western and Northern Region, recently had two interesting big brown bat submissions. One bat had been submitted to a rehabilitation facility in October 2013 after being found on the ground by members of the public in Saskatoon. She had bruising around her shoulder and was described as “bitey” when being handled. The second bat was found in a local church on January 10th, 2014, captured in a container and taken to the same rehabilitation facility. This male bat had crusting lesions on his chin. The bats were housed individually under conditions that would induce normal torpor or hibernation but they were reluctant to drink and had lost weight. There was difficulty regulating the temperature of the hibernation chamber, with the temperature dropping below 4 C rather than maintaining the desired temperature range of 6 – 9 C. The bats subsequently died within 2 days of each other (the female on February 16 and the male on February 18) and were submitted for autopsy the following day. On examination of brain tissues under light microscopy characteristic rabies virus inclusion bodies, so called negri bodies, were observed and immunohistochemical stains, specific for rabies, confirmed the diagnosis. As there was no history of direct human contact, samples were not sent to the Canadian Food Inspection Agency (CFIA) rabies lab until after the diagnosis was made by CWHC.
These cases are interesting for several reasons. First, it highlights the importance of bats as a source of rabies in Canada, and elsewhere, and the potential of bats to come into contact with humans. Big brown bats often hibernate in buildings and for that reason are found frequently by members of the public. Live bats are commonly taken to rehabilitation facilities due to public education campaigns stressing the importance of these often maligned animals. Fortunately this rehabilitation facility had taken precautions to prevent human exposure. We have had similar situations in the past where bats have tested positive while being rehabilitated and precautions had not been taken which resulted in post-exposure treatment of people and considerable anxiety for those involved. These two cases are also interesting because of the long incubation period observed in these bats, assuming they were suffering from rabies at the time they were submitted to the rehabilitation centre and they did not have contact with each other.
Finally these cases are also noteworthy as it highlights the changing role of the federal Canadian Food Inspection Agency in rabies diagnosis and surveillance. The CFIA will only test animals for rabies when there is a human health risk but will confirm the diagnosis of positive tests from non-human health risk cases done in other laboratories. The Canadian Wildlife Health Cooperative, and other similar agencies, have now taken on primary responsibility for diagnosis and surveillance of rabies in wildlife. Appropriate precautions should always be taken when handling bats in order to prevent exposure to rabies and other diseases.
Just noticed the different name for the CCWHC in the above article (written as CWHC and The Canadian Wildlife Health Cooperative). Is the name of CCWHC changing or was it a typo?
Thanks for your help!
Thank you for noticing Erin! Indeed, we are changing the name of the Canadian Cooperative Wildlife Health Centre (CCWHC) to the Canadian Wildlife Health Cooperative (CWHC). Hopefully this will make it less of a mouthful and easier for people to remember the full name!
So is it still a good idea to put up bat houses or is too risky to attract bats with rabies to my yard
Hello Ken. While a small proportion of bats do carry rabies, and rabies is a significant disease that should be considered seriously, if one does not handle bats or put their hands into the bat box, the actual risk of getting rabies from a rabid bat from a bat box is very small. The benefits of having bats around your yard (insect control) greatly outweigh the risks if these simple precautions are followed. Rabid bats may show odd behaviour that can result in them being out in daylight hours and/or ending up on the ground, and grounded bats (any bats actually) should never be picked up with bare hands. It is also important to keep domestic animals away from grounded bats to minimize the risk of contact between the bat and the domestic animal. It is well documented that dogs, cats, horses and livestock can get rabies from bats which can lead to secondary exposure of their owners. It is important that grounded bats are collected by the local wildlife division and submitted to a CWHC lab (1.800.567.2033) so that it can be tested for rabies and assessed for other health problems. If rabies is confirmed in a captured bat that was behaving abnormally, post exposure rabies treatment may be required for the pet and/or any human deemed to have had significant contact with the rabid bat. Always contact your local medical health officer or physician if you have concerns about human or domestic animal contact with a bat in your home or on your property.