Bats Infectious diseases

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Bats Infectious diseases

Postby bigalpha » Jan 13, 2007 11:40 pm

Are there any widespread infectious diseases spread solely by bats?

Watching the Al Gore movie, and bats were listed as an animal that can carry infectious disease. Any truth to that?
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Re: Bats Infectious diseases

Postby PamSales » Jan 14, 2007 6:56 pm

bigalpha wrote:Are there any widespread infectious diseases spread solely by bats?

Watching the Al Gore movie, and bats were listed as an animal that can carry infectious disease. Any truth to that?


Any mammal can be a carrier of infectious diseases, so...yes, bats can. As can cats, dogs, humans, cows, and squirrels. To the best of my knowledge, there are no diseases that only bats carry.
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bat infectious disease

Postby kmstill » Jan 15, 2007 7:25 am

I assume you're actually interested in the bats roles in zoonotic disease (infectious disease of animals that can affect people). There are several, but really only a few that apply in the US.

Of course, Rabies is the big concern in the states, with 2-5% of the bat population being rabid. Also, in the states, the majority of human rabies cases are the bat rabies strain. However, the NSS did a decent survey study a while back, effectively showing that the rabies risk to cavers (from caving alone, don't mess with the bats and report any bites or bat to human contact to your health professional) was effectively nil. The suggestion that rabies can be spread by aerosolized fecal/urinary bat waste is caves comes from 2 cases of people in caves who contracted rabies without know/identifiable bat bites - this was quite a while ago and I believe that they were together and contracted the disease at the same time. Considering the NSS study, the plausibility of an aerosol route being a significant risk is pretty low (considering the # people caving - exposures - and the low rate of rabies vaccination among cavers, if aerosol was a significant risk we'd have a lot more rabid cavers). Really up to you and your docs if you want a pre-exposure vaccine though. FYI, fun fact, Australian Bat Lyssavirus is a virus VERY close to rabies, found in Australia, and carried by bats.

Histoplasmosis is the other major concern to cavers in the US. This is a fungus that causes respiratory disease, and is more of a risk in some caves than in others. Birds also shed histo, but bats are the major source underground! People that live in histo-prevalent areas may have developed a level of immunity, while others that come in just for caving, and hit a high risk cave, are more likely to get sick.

There is world-wide evidence that bats can carry pathogenic leptospirosis strains, but I don't know specifically what the risk is in US bats. Lepto's a bacteria shed through the urine that can cause kidney and reproductive disease. A lot of other mammals are carriers/ and susceptible to this, so don't play w/ pee and wash your hands. Lepto can be contracted from urine contaminated waters (just try to find a stream that a rat or deer hasn't peed near!) or by getting splashed in mucous membranes by contaminated pee (more of an issue for farm workers and vet professionals), but these aren't really cave related risks.

And then there's a few other fun diseases from other parts of the world. Bats are believed to be the reservoir species for both Hendra (Australia) and Nipah (Malaysia, Bangladesh) viruses. Neither of these disease have been in the US. Also, a variety of corona viruses and a corona-like virus have been identified in bats in SE Asia; the latter is the link that has tentatively implicated bats as the origin of SARS, though this is NOT proved, and there are a few other contenders (specifically, rats and cats).

As already mentioned, any mammal species carries a risk of disease for humans, and many of them are much more likely to actually affect you than the bat diseases. Proper hygiene goes a long way to interrupting the transmission of many disease, and avoiding human-bat (physical) contact is best for you and the bat. If you need to handle bats (eg research) you need to be vaccinated for rabies. If you have unintentional physical contact with a bat (even if you don't think you've been bit) you need to talk to your doc about post-exposure vaccination. Happy (disease-free) caving.
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Postby fuzzy-hair-man » Jan 15, 2007 7:04 pm

Thanks Kelly, very informative.

About the Australian bat diseases do you know which species of bats these are usually prevalent in? and can they be carried by any bat species? could you point me in the right direction?

I ask because quite a while a ago there was several cases of human infections and even deaths (if memory serves me correctly) and these were from people who had handled fruit bats (fruit bats are a large native species which has a wing span of up to 1.5 metres, they roost in trees and don't enter caves. fruit bats)

Generally we don't bother about contracting anything from bats whilst caving so it came as a bit of a surprise that there were diseases that were carried by aussie bats.
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Postby kmstill » Jan 15, 2007 7:10 pm

Off the top of my head - I the fruit bats have been implicated with the Nipah and, I think, Hendra viruses. I believe the Australian Lyssa virus is most often associated with the flying foxes; I don't know if its been identified in other species. To my knowlege, there hasn't been documented direct bat-human transmission of either Nipah or Hendra. Nipah was generally picked up by swine feeding on fruit w/ infective guano and hendra was primarily a horse disease with a few human cases on the side, presumably from exposure to the horses. Both of these disease are considered emerging, and the body of knowledge on them is far from complete. L
Lyssa virus is a different story; its behavior is effectively identical to bat rabies. Some of the bat biologists out there might now better/more current. I'll check around and let you know if I dredge up more info.
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Postby fuzzy-hair-man » Jan 15, 2007 7:39 pm

kmstill wrote:Off the top of my head - I the fruit bats have been implicated with the Nipah and, I think, Hendra viruses. I believe the Australian Lyssa virus is most often associated with the flying foxes; I don't know if its been identified in other species. To my knowlege, there hasn't been documented direct bat-human transmission of either Nipah or Hendra. Nipah was generally picked up by swine feeding on fruit w/ infective guano and hendra was primarily a horse disease with a few human cases on the side, presumably from exposure to the horses. Both of these disease are considered emerging, and the body of knowledge on them is far from complete. L
Lyssa virus is a different story; its behavior is effectively identical to bat rabies. Some of the bat biologists out there might now better/more current. I'll check around and let you know if I dredge up more info.


Wow quick reply!!

I remember a story about a horse trainer dying, and sort of remembered some tie in with bats but couldn't remember why, so that strikes a chord.

The Nipah one is new to me....

I just found this on Lyssavirus maybe we should be taking this thing a bit more seriously :question: :bat: they still only seem to be concerned with fruit bats though even though they say:
Insectivorous bats are known to carry other Lyssaviruses overseas and therefore cannot be discounted as a potenital risk, at this stage.


Oh well something to ponder....
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re: bat infectious disease

Postby kmstill » Jan 15, 2007 9:58 pm

Just a FYI to clarify-
Rabies is a type of Lyssa virus; so is the Australian Bat Lyssavirus. I have heard the (tongue-in-cheek?) suggestion that ABL got it's name just so that Australia can remain "officially" rabies-free. Now, I'm not so cynical as to believe that :laughing: , and I haven't studied up on the differentiating viral characterestics, but my "in-a-nutshell" education on ABL was to basically consider it like rabies until I heard otherwise; not being in Australia, this seems sufficient. But the "lyssavirus transmitted elsewhere by insectavorous bats" reference was most likely about rabies.
Regardless, even in the US, the evidence regarding rabies exposure as a risk of caving does not seem to justify mass vaccination of cavers or avoidance of the sport. Your local physicians should have a better idea of what the real risk of ABL is to people and cavers out your way. Good luck, happy caving, and as always: look at - don't touch (harass, catch, feed, cuddle, kidnap, play with...) the bats.
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Postby bigalpha » Jan 16, 2007 9:46 am

Holy smokes Kelly,

That is a a whole lot of cool information.

I knew that bats can carry rabies, but that it wasn't a prevalent problem. I didn't know about the possible SARS connection.

So, bats aren't really a problem with carrying infectious diseases, then? It may be possible to get infected with some virus, but not very likely for the 'average joe'.
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Postby kmstill » Jan 16, 2007 9:11 pm

Histoplasmosis is a valid concern - one example, Climax cave (GA) is known for histo and I'm sure there are others (any comments here from the rest of the list) - but you can also catch histo above ground. Seems like people that live in histo prevelent areas of the country may get enough small early exposure to build some tolerence - docs on the list care to chime in? - while others certainly have gotten sick from caving. exposure to histo comes from breathing in spores stirred up from the feces/dirt. Practically speaking, I don't know that cavers are doing much about this, other than avoiding some caves with a bad rep - cavers, anyone out there care to comment more?

Rabies certainly should be expected in any bat colony, but transmission requires a bite (which can be small enough not to be notice by the victim) or intimate fluid contact with your mucous membranes. I don't buy the aerosolized guano theory. I'm personally not worried about the rabies risk, but I'm also vaccinated already for non-caving related reasons. If I wasn't though, I'd doubt I run out and get vaccinated just for caving (NOTE: that is not medical advice, just a personal statement).

I've never heard of anyone catching leptospirosis through caving (again, requires ingesting or intimate mucous membrane contact with the bacteria - often through water contaminated by urine; plenty of above ground mammals carry and shed this disease).

SARS link is not definitive; and SARS isn't really in the US anyways. Don't know what the exact transmission method to humans (if it actually exists) is supposed to be. Hendra, Nipah, and ABL are not in the US.

Disclaimer, while I do know about disease in the animal populations and the related public health concerns, I'm not legally (or by professional ethics) allowed to give human medical advice. Either the physician cavers should chime in here or you should have a chat with your favorite doc-in-the-box to decide what YOU should/should not do (though bewarned, not all physicians will have an equal understanding of caving, bats, or the risks they do/dont pose). Also, some people's underlying health may allow them to tolerate the risk of some diseases (like a respiratory infection w/ histo) better or worse than the population at large. I don't know you or your health, and I don't do human medicine, so I really can't (and won't) tell you what personal medical decisions to make. Also, all of us have different levels of risk adversity (so my choice may not equal your, and yours not equal Jon Doe's), and caving is inherently dangerous regardless of any disease risks.
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bats and leptospirosis

Postby cavedoc » Jan 17, 2007 2:35 am

kmstill wrote:I've never heard of anyone catching leptospirosis through caving (again, requires ingesting or intimate mucous membrane contact with the bacteria - often through water contaminated by urine; plenty of above ground mammals carry and shed this disease).


I know of two cases. One of which I published. These are from some expeditions to the Mulu area of Borneo. The Brits report several more cases caught there too. When I was researching this I found that leptospires survive much better in water with a basic pH. So risk in karst might be higher than water elsewhere.

I'm not aware of any cases in the USA.

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Postby kmstill » Jan 17, 2007 6:42 am

thanks. could you send me the references if you have them?
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Postby Teresa » Jan 17, 2007 8:31 am

histo likes dry dirt, hence the problem when caving in dry bat caves. But histo is also ubiquitous where ever chickens and other poultry are raised 'organically', and as others have said 'outside'.

The answer: cave in wet caves, and never go outside.

I understand some people in SE Asia have gotten sick from eating bats, too. Not that this a big problem; just if someone offers you bat, check for the purple stamp to see that it has been federally inspected by Dept. of Agriculture to be disease free.

You are more likely to catch something noxious from that fool sneezing in your face in the elevator than from most wild animals (with the sole exception of animal bites.)
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Rabies

Postby monicak » Jan 17, 2007 10:21 am

Thanks for the terrific review.

Many years ago (late 70's), a researcher acquired Rabies from an aerosolized live virus. It was the first case and the mechanism was very clearly documented. Kind of a tragedy, the woman was working on developing the preventative vaccine at the time. She had not been vaccinated and was sprayed on the job. She was one of the first survivors of Rabies but she had significant neurological deficits.
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Postby John Lovaas » Jan 17, 2007 10:50 am

I was one of the folks who got histo from a visit to Cueva Carrizal(sp.?)in northern Mexico after the Bracketville, TX NSS Convention. I was interviewed by the CDC, and they got some of my blood as well. I believe the results of the CDC survey were published in the NSS News- I may be mistaken there.

The people in our group who contracted histo spent their entire trip in the stream portion of the cave- we never set foot in the dry, "histo-prone", sections of the cave. Of the 6 in our group, three contracted histo; one was a smoker, and the other two(myself included) had jobs in a workplace filled with burning oil vapor, paint solvents, and a variety of other aerosol byproducts of commercial steel heat treating and processing.

There was a lot a lot of talk at the time(and a mention in this thread) that there is, or may be, some sort of acquired immunity to histo. If someone has any references to any clinical reference or study that supports the case for acquired immunity, I'd love to see it. The only references to "immunity" that I have ever found are in caving publications- and those references are always unsupported. What is known is that the condition of your immune system, and the dosage of histo spores that you inhale, are the two factors that determine your succeptability.

I know some folks believe a bandana or dust mask can protect you. The size range for histo spores(that I can find documentation for) is from 5 to 9 microns. That is a SMALL particle(a morel spore is around 24-26 microns in diameter), and if you really want respirator protection, you'd be better off with some kind of powered respirator or self containted apparatus.

All this being said, more than 90% of the documented histo cases out there are caused by bird guano exposure. So when we spend time anywhere large groups of birds congregate, we are at the greatest risk of histo exposure.

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Re: Rabies

Postby kmstill » Jan 17, 2007 6:17 pm

monicak wrote:Thanks for the terrific review.

Many years ago (late 70's), a researcher acquired Rabies from an aerosolized live virus. It was the first case and the mechanism was very clearly documented. Kind of a tragedy, the woman was working on developing the preventative vaccine at the time. She had not been vaccinated and was sprayed on the job. She was one of the first survivors of Rabies but she had significant neurological deficits.
Monica


Thanks, hadn't heard of this one - will have to look it up :kewl: . The PH people I've talked to/been lectured by have always cited the 2 cases supposedly associated w/ cave exposure (texas?), or so I remember - very possible that things got scrambled between the ears and the brain. Lab associated aerosol exposure seems much more plausible, but still not quite the same as caving. Gotta run for now, but this has been great. Starting a good discussion w/ one of my animal techs as well - education for everyone!
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