I am wondering if bat rabies occurs often in winter, if bats can carry the disease without contracting it, what the incubation period is once they contract it and how long they will live with the disease once symptoms show.

Justin (HD wildlife) would be the one to know but I've always been under the impression that rabies acts upon bats like it does any other mammal without any sort of latency or lag time between infection and death. Now with bats entering torpor in the winter I again assume a lower rate of infection due to non interaction but the question in my mind is how does the virus overwinter. Does the bats lowered metabolism allow infected bats to survive into spring to infect other bats?

Again, Justin would be the authority, but it seems to me that I've heard that bats? can carry rabies and not die from it. ( Of course, I've heard that the moon was made out of green cheese too )

Thought that was Blue Cheese ....

I can tell you incidences of reported bat rabies go down in winter here, that is the bats tested have a lower % testing positive for rabies. The health depts. here want to test every one found inside living spaces and extreme cold weather seems to make the overwintering bats enter living spaces more readily. Always get a more calls when it is extremely cold.

Jim,

From the research I've reviewed there aren't a lot of solid answers with this. There is a documented case of 16 Big brown bats being sent to Norway (or somewhere over there) for research purposes where all 16 bats died from rabies during the quarantine period. What is unique about this situation is that the bats were divided into three separate groups with their own container upon arrival. If I remember correctly, the first bat began showing systems about 3 weeks into the quarantine period and the last bat dying 13 or 16 weeks later.

I've also seen researching discussing the potential for bats to carry the virus for 2 or more years before succumbing to it. I'm not sure how "normal" this would be, but when looking at the previous example, at least one bat in each container had contracted the virus before they were separated. On the bare bones side, that means that at least one bat lived quite some time before expiring as the bats would have been collected then gone through an export quarantine, shipping time (I believe they were sent by boat), receiving time, and at least 21 more days if it was the first one to die.

The problem with using "once symptoms show" as a reference point is defining what symptoms can be decisively attributed to rabies versus normal behavior. For instance, biting is a common function especially at specific times of the year so if an infected bat bites, is it because of rabies or is it natural behavior. I've had several bats tested that crawled "towards" people while making loud noises and they have all come back as negative (which really surprised the heck out of me). So on a personal level, the only "symptom" I would lean towards a rabies infection would be loss of muscular function to include falling from roosts with difficulty moving/flying. Of course with bats you also have to be careful that the bat was not dislodged during torpor and is just waiting for its muscles to warm up. Remember, the only way to know for sure is to have it tested.

From a purely speculation perspective, I'd say that hibernation slows the spread of the rabies virus thus allowing the bats to live longer than potentially other mammals of similar size and biological function. The body temperature drops from about 96 degrees to about 45 degrees and the resting heart rate will reduce considerably (sorry, all I can remember is that a bat flying has a heart rate over 300 bpm but I can't remember the resting rate or the hibernative rate and bear in mind that this is all species specific). Of course, this is also why white-nose infects so many bats during this time frame as their immune systems are shut down allowing the fungus to establish itself into the tissue.

I am glad that I asked and thanks for the help. What everyone is describing is very close to my own suspicions, rabies going dormant for extended periods in winter. It has to over winter in some host as it pops up every spring.

The reason for asking was that a friend's wife found a bat on the floor, alive, this morning and tossed it out into the snow and later it was gone. In the 30's, I doubt it flew off, but may have crawled into a crevasse. I don't think anyone had any blood or saliva contact or was bitten. However, the bedroom door was open and I have heard a bat can bite a person at night without anyone knowing. Rabies is just plain scary. I referred them to the health department on the spot when they told me the story. Best to err on the side of caution with rabies.

Thanks again for the input.

Jim, I believe your state is pretty firm on sending folks for shots and bats in living area may be a reportable event but I may be wrong.
Here it is homeowner discretion to seek medical help and it's not monitored by the state. We are advised, not required, to attempt to determine if a person has handled, been bitten or scratched. If so we again are advised to have the animal tested by the county animal control. Lots of leeway and cya on the state's part that can leave a NWCO swinging in the breeze.

Good answer Eric,

There was a recent publication, though its late and I can't seem to find it easy, but it discussed that bats can overwinter with rabies. This was through active
sampling of bats in hibernation.

Though most folks likely err on the side of caution, so many factors play into the bats emerging during winter or warm ups during winter that dehydration, thermal seeking behavior, etc... can all be reasons why bats are found in the house all of a sudden, versus they are rabid.

Eric put it a good way about behavior, often folks call folks like us with bats that are simply in torpor (sleeping) and they think the bat is sick or dying, while the bat is perfectly fine. If you've ever handled (with gloves of course as you should) a bat fresh out of torpor, it can take them anywhere from a minute to several minutes to fire up the engine and become normal acting.

In the meantime they can grimace and make movements that cause many folks to get a sketchy feelin, while it is akin to a family story....

My dad always told me never wake your gramp from his chair while he's sleeping. Why? Because he had a knee jerk reaction that often caused a fist to fly in your direction! Not a violent man, but woke up startled and often nearly nicked whomever was doin the waking.

So, moral of my story would be folks should know when a bat bites you it does indeed hurt, yes they can get saliva or urine etc... on you or your bare skin, but when we are talking odds, we need to always relate what we feel comfortable with within our states guidelines. Many states are way over on one end, some are on the other in terms of reaction.

When the reaction is "Oh my gosh there was a bat in your house?! We need to get everyone in your house and your family tree and neighbors shots ASAP!!"

Someone needs to be a voice of reason.

Every NWCO has to live with their own decisions related to wildlife and potential disease risks, damage risks, parasite issues or concerns as they see fit to keep them in good stead with their clients and with their governing bodies.

This winter we ended up the only folks in the area who could take on some injured bats (from domestic cats, wing tears), though I've spent tons of time around thousands of bats in field surveys and in exclusions now, having two silver-haired bats that share our space has taught us much much more. Beyond amazing creatures.

***

On a side note, we should expect the cases of rabies would dip in winter in states with hibernation anyway, due to limitation of exposure, versus the main season when we expect more folks with windows, doors and other entry points open and many more times the activity going on.

Kind of like knowing you'd have a better shot of being mauled by a bear during summer than dead of winter when they are hibernating....

I'll see if I can find that publication, was on BCI's site months back...

Justin

After reading the posts I definitely have a better handle on bats vs. rabies, confirming what I believed was likely. In this case I not was called in to remove or participate, but just offer some input after the fact. Getting second hand information about what happened in the beginning, wrought with omissions, I only found out last night that the bat was found in the bedroom after I called them back, worst case scenario. There was a warm up, first one all winter, so I suspect that temperature change caused the bat to wake and move. As mentioned, a stirring bat in winter surely does not mean rabies is present. There was no actual contact with the bat and the cats have had their shots. I wonder if a bat waking in winter in apt to fly? How much energy would he have for how long? The only thing our health department says is that a bat can fly and bite at night without the person knowing it, so they err on the side of caution and recommend a precautionary shot if the bat can not be tested when found in a bedroom. At least its not the once rumored 17 shots in the stomach I used to hear about as a kid. It would seem that the odds are incredibly low of contracting the disease in a case like this, but with the seriousness of rabies, I defer to the state's recommendations and let all the parties choose the path that suits them, while just providing the facts as I know them. Lisa said, "you are scaring me." I said, I'm just passing on information and if you are scared it's your call.

In all rabies cases common sense and intuition must prevail. I had a call quite some years back, a raccoon problem. A raccoon had been seen in the dead of winter in the middle of the day for several days, something I was told well after the fact. The coon had tried a couple of nights to enter the home of an elderly woman through the cat door, which scared her to death. At that time I had no double door cage traps, but set a 220 in the opening under the home. I also set 2 baited cages, but told the woman that if the coon was late stage rabies he likely would not respond well to bait. Turned out the 220 did the job, first night as I remember. The lady's cat had been fighting with the coon, but the health department told her not to worry, no testing was necessary. In that case I intervened and simply said, "you can do what you like, but if it was my decision I would definitely have that coon tested, without hesitation." Of course the coon came back positive with rabies and the veterinarian went bonkers because she was not told the whole story either. She didn't know she was handling a cat that had been exposed, but should have taken all precautions anyway it would seem in any raccoon or skunk fight between either of them and a pet, especially with the prevalence of the disease in our area. Raccoons have been nearly non-exsitant in this area since the first case of rabies more than 15 years ago, quite scarce.

The American Society of Mammologists have published several white papers asking for the medical field, health departments, and wildlife divisons to stop saying you can be bitten by a bat and not know it. Those of us that have been bitten will agree with that statement. Of course, there are always exceptions (person cannot communicate due to age, disease, etc or was incapacitated at exposure time) and they note that, but as Justin said some states/people way overdue it while others go the opposite direction.

It does seem like a bit of a stretch about the biting, but with liability suits rampant, always someone to blame, some tend to go to extremes. I only know of one instance where a Wisconsin girl survived rabies after entering into an induced coma. Maybe there have been others? I know they tried the same in India, but it failed, so the disease is pretty much 100% dirt nap after the fact, scary.

What Jim said; the apochryphal case of the girl surviving (possibly misdiagnosed) rabies notwithstanding, rabies is considered 100% fatal. I would be remiss in my professional duties to treat any possible transmission as anything less than a serious situation.

Sounds melodramatic, but I don't think I'd like myself if I took the know-nothing approach and the unthinkable happens. Oh, yeah, and some lawyer is gonna sue me right down to my toenails.

Yes, there was a definite case of rabies survival in the young Wisconsin girl not that long ago. It was not misdiagnosed. She was bitten by a rabid bat in church. She picked it up and released it after being bitten. The doctor tried something new and got very lucky. Check it out on line, the complete story is there. I watched and read it all. The disease in this case did not progress when the coma was intentionally induced, which stopped the progression and allowed her own immune system to fight and kill the virus over a period of time. She is not 100% the last I heard, but improving, still with side effects. Perhaps in time she will continue to improve.