Knowledge of Bat Rabies and Human Exposure Among United Stat

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Knowledge of Bat Rabies and Human Exposure Among United Stat

Postby Lynn » Sep 13, 2005 12:02 pm

Knowledge of Bat Rabies and Human Exposure Among United States Cavers
from Emerging Infectious Diseases
Robert V. Gibbons, Robert C. Holman, Stephen R. Mosberg, and Charles E. Rupprecht

Abstract and Introduction
Abstract
We surveyed cavers who attended the National Speleological Society convention in June 2000. Fifteen percent of respondents did not consider a bat bite a risk for acquiring rabies; only 20% had received preexposure prophylaxis against the disease. An under-appreciation of the risk for rabies from bat bites may explain the preponderance of human rabies viruses caused by variant strains associated with bats in the United States.

Introduction
Over the past century, human rabies has become exceedingly rare in the United States. The decreasing incidence of human rabies has followed the decline of rabies in domestic dogs. From 1946 to 1965, 236 human Rabies virus (RABV) infections were reported in the United States. From 1946 through 1949, the number of human RABV infections averaged 24/year, declining to 1.5/year from 1962 through 1965. Ninety percent of RABV infections were caused by dog bites from 1946 through 1949, decreasing to 67% from 1962 through 1965[1]. As canine rabies declined, the relative importance of other reservoirs in the United States increased. From 1970 to 1989, human infections averaged 3.3/year. Of these infections, 45% were caused by canine RABV variants (all but one was acquired outside the United States), 30% were caused by bat RABV variants, and one was caused by a corneal transplant from an unsuspected rabies patient[2,3]. From 1990 through 2000, bat RABV variants have emerged as the predominant cause of human rabies in the United States[4]. In the past 11 years, total human rabies deaths have averaged 2.9/year, and 24 (75%) of 32 deaths were due to bat RABV variants. If the six cases caused by foreign canine RABV variants are excluded, then 24 (92%) of the 26 human rabies deaths acquired domestically were caused by bat RABV variants. The other two cases were due to a dog/coyote RABV variant found in Texas[4].
Confusion remains about potential exposures to rabies from bats. Only 2 (8%) of the 24 patients with human rabies caused by bat RABV variants had a definitive history of a bat bite. Nine patients (38%) had a history of direct physical contact with bats, 5 (21%) had a history of a bat inside the living area, and 8 (33%) had no history of proximity to bats[4]. Because of the paucity of bat (or other animal) bite histories, could these human rabies cases have been acquired through aerosol transmission? The diagnosis of rabies in two people who had no known history of a bite, but who worked extensively in caves inhabited by bats, received considerable attention in 1953[1,2]. Although the aerosol route is considered a possible mechanism of RABV acquisition, few data support such transmission under typical field conditions. A more plausible hypothesis is that many people may not be aware that a bat bite is a risk for rabies transmission and fail to report it.

Because of the potential contact with bats, cavers are considered at a higher risk for rabies exposure than the general population. Since the 1960s, the recommendation has been that the cavers receive rabies preexposure prophylaxis (PreEP)[5]. The objectives of this study were to learn about cavers' knowledge of the risks for bat-to-human rabies transmission and to quantify cavers' use of rabies PreEP prophylaxis and postexposure prophylaxis (PostEP).


Robert V. Gibbons, Robert C. Holman, Centers for Disease Control and Prevention, Atlanta, Georgia, USA; Stephen R. Mosberg, National Speleological Society, Huntsville, Alabama, USA; and Charles E. Rupprecht, Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Dr. Gibbons is a medical officer with the Department of Virus Diseases at the Walter Reed Army Institute of Research. His main area of interest is dengue vaccines.

http://www.medscape.com/viewarticle/432550
Note: Just noticed this is an article from 2000. Any one know the current status of this research?
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Postby hewhocaves » Sep 13, 2005 1:45 pm

a few things...

one: Isn't the reason for the "increase" in bat rabies simply a statistical misonception because we've reduced or eliminated every more likely spot? Isn't it also possible that the 'increase' in bat rabies bites are because they have been misdiagnosed as other forms of rabies in the past?

two: does bat rabies (even for cavers) fail the "being killed in a car" test? That is, are you statistically more likely to be killed in a vehicular accident?

three: doesn't the caving communities increased awareness of how to coexist with bats mitigate their chances of increased exposure (and doesn't the number of caves with both cavers and bats pretty much eliminate the idea of airborne rabies distributed by bats?

four: are bats actually affected by rabies or are they simply carriers?

I'm not saying that a rabies vaccine isn't a good idea, but is it necessary when weighed against the risk. Should we treat it with the same seriousness that we treat helmets with (i.e. absolutely essential)? Do we then go ahead and require it of all people before entering a cave (you can see the slippery slope developing here - Imagine Boy scout groups!)

the point that I'm blindly stabbing at here is that while we should applaud a study like this for it's research, I wouldn't want far ranging reforms enacted without a heckuva lot more evidence. Fortunately from the blurb, this article seems to be strictly an FYI sort of thing.

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Postby JackW » Sep 14, 2005 10:57 am

If the CDC states that cavers should be inoculated due to the greater chance of contact with bats, then this begs the question of how many cavers have contracted rabies and/or the number of suspected exposures requiring inoculation?

In my 10 years as a caver I've handled 2 bats: One was stuck in duct-tape on a light battery after a fellow caver came out of a tight crawl. The second time was when a hibernating bat was knocked off the wall by another caver. I picked it up and re-hung it. Both times I was wearing gloves. In my opinion the handling did not constitute contact and I was not worried nor believed it warranted rushing off to the doctor for inoculation.

Recently, I went on a trip to Nevada helping with a bat netting project. I did not handle the bats but was in close proximity with the bats. I did look into getting the pre-exposure inoculation prior to the trip but didn't get it. I talked with my doctor and he said "yes" AND my insurance would have picked up the tab. Part of my thinking against the pre-exposure shots was that the inoculation is a "pre-inoculation" of three shots. If you have a contact such as a bite, then you go and get more shots after the fact. The primary research on the trip wore leather gloves when handling the bats caught in the net.

So how does this tie in to my above question? I believe the above question's answer is going to be few to none in the past 20 years and I further believe that my habits in regards to bats prevents a rabies exposure.

Some how this discussion seems familiar...
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Stats for Cavers who got rabies?

Postby icave » Sep 14, 2005 12:21 pm

Does anyone out there have stats on the number of cavers who have gotten rabbies? I understand that cavers have a greater exposure to bats, but has that translated to a larger percentage of documented cases of rabies? To me, that is the big question.

I've seen no hard evidence that caving generally increases one's risk for rabies. I'm not talking about going into caves with TONS of bats, but normal caving. I would also be interested in knowing what the stats are for people who regularly interact with larger numbers of bats are though.

Any stats ot there on rabies and cavers?

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Postby Squirrel Girl » Sep 14, 2005 12:34 pm

I know of only two cavers who have been bitten by rabid animals. One was a cat (presumably rabid), and the other, a dog (tested and rabid). I've never heard of non-bat biologists caver types every being bitten by bats.

It does make one think about taking a nap in a cave, though......

And, of course the discussion is familar. Lots were previously discussed and lost when the old board crashed. :roll:
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Postby filox1 » Sep 14, 2005 2:00 pm

Hi all,

Any body knows if the bats Carie flies, and can this flies be transmitter's of deceases like rabies.

how about other bat caring parasites... is there a studies on that?

Offcourse on other stand point a mosquito that you may encounter in your way to the cave is lots more dangerous that the bats.

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Postby Squirrel Girl » Sep 14, 2005 3:32 pm

filox1 wrote:Any body knows if the bats Carie flies, and can this flies be transmitter's of deceases like rabies.
Bats have mites. I don't know if they transmit diseases, but they won't carry rabies. It's mammals, only. I think Tropicalbats is off on a bat net project or something or other this week. Maybe when he gets back, he'll have more info.
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Postby hunter » Sep 15, 2005 5:33 pm

This topic kind of got me thinking because I was once run into by a confused bat while crawling. The bat, after running into me, ran across my back and took off.
To the point, I looked around and couldn't find any human rabies cases which mentioned caving.
I did however find the following:

- The majority of rabies deaths in the US are caused by a rabies variant found in bats. This contrasts with most of the rest of the world where some 35,000-50,000 rabies deaths occur due to dog bites, which carry a different strain of rabies. (Ref 1)

- Unlike the world number, the statistics for US human rabies cases from 1980-1996 was: "32 cases, 17 (53%) were associated with rabies virus variants found in insectivorous bats" (Ref 2)

- All 32 cases of diagnosed human rabies in the US from 1980-1996 resulted in death, (Ref 2) as did all cases from 2000-2003 (Ref 3).

-Due to a large number of deaths in which no bat bite was remembered by the person or relatives this statement is made: "In addition to situations involving an animal bite, a scratch from an animal, or contact of mucous membranes with infectious saliva, postexposure prophylaxis should be considered if the history indicates that a bat was physically present, even if the person is unable to reliably report contact that could have resulted in a bite." (Ref 2)
- The majority of rabies deaths in the US from 2000-2003 were caused by strains associated with bats. (the total is like 12 deaths I think)

- The NSS website actually refers to two cavers getting rabies but not much info is given. (Ref 4)

Anyway, after reading the references below my personal feeling is that if you are exposed to a bat with skin contact the shots are smart since I could find no documentation of a person recovering once rabies was diagnosed.

Anyway, my .02

Hunter

References:
1) http://www.cdc.gov/ncidod/EID/vol9no2/02-0083.htm#1
2) Noah DL, Drenzek CL, Smith JS, Krebs JW, Orciari L, Shaddock J, et al. Epidemiology of human rabies in the United States, 1980–1996. Ann Intern Med 1998;128:922–30.
3) This page has links to CDC rabies reports for 2000 - 2003:
http://www.cdc.gov/ncidod/dvrd/rabies/P ... ofessi.htm
4)http://www.caves.org/section/medical/rabes.htm
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Postby hewhocaves » Sep 16, 2005 11:46 am

Squirrel Girl wrote:I know of only two cavers who have been bitten by rabid animals. One was a cat (presumably rabid), and the other, a dog (tested and rabid). I've never heard of non-bat biologists caver types every being bitten by bats.

It does make one think about taking a nap in a cave, though......


you're worried about being bitten by a dog???
:waving:

I'll go away now ;-)

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Postby hewhocaves » Sep 16, 2005 11:52 am

hunter wrote:Anyway, after reading the references below my personal feeling is that if you are exposed to a bat with skin contact the shots are smart since I could find no documentation of a person recovering once rabies was diagnosed.


I believe the first succesful recovery from rabies happened this year by placing the patient in a coma. (recovrey may be premature... survival is more appropriate at this juncture). Here's the link:

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5350a1.htm

Circumstantial evidence puts it at a bat bite. she picked it up.

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Postby Phil Winkler » Sep 16, 2005 12:14 pm

Actually, several people have recovered from rabies. One of the earliest was a youngster named Matthew Winkler (no relation) whose doc treated him symptomatically--at the time a novel regimen. As I recall his doc may have been named Winkler, too. What are the odds of that?

A bunch of cavers, myself included, got immunizations back in the 70s when we were in the Army and got them for free since one of our cavers was also an Army doc.

Any vetinarian or other animal handler gets immunized and checked routinely.

Bats have rarely been implicated in rabies cases except for a highly publicized incident in Frio Bat Cave in Texas where bat urine and/or mites were suspected of being the vector for infection.
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Postby Squirrel Girl » Sep 16, 2005 12:25 pm

hewhocaves wrote:you're worried about being bitten by a dog???
I do when I go caving in foreign countries. Rabies in dogs is bad enough in Latin American. It's many times worse in India.
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bat rabies transmission

Postby tropicalbats » Sep 18, 2005 12:08 am

Hey Skirl Gurl,

Squirrel Girl wrote:
filox1 wrote:Any body knows if the bats Carie flies, and can this flies be transmitter's of deceases like rabies.
Bats have mites. I don't know if they transmit diseases, but they won't carry rabies. It's mammals, only. I think Tropicalbats is off on a bat net project or something or other this week. Maybe when he gets back, he'll have more info.


This topic is interesting. The problem is, so to speak, that so few people die from rabies in the US that it gets little scientific attention. Let's face it, 1.5 dead people per 300 million just isn't high on the fatality charts. But, it always makes the news (apparently because it is so rare and gruesome), and cavers to need to know about such things and assess their own risks.

As to parasites passing on rabies, this could be true. As to air transmission of rabies this could be true. As to polar bears giving rabies to seals this could be true. But at the end of the day, there is very little science showing how all this works, and using the theory that the "ends disproves the means" shows that cavers and bat biologists around the world are not keeling over by being in contact or proximity to bats.

I am a bat biologist. I have been vaccinated since maybe 1995, and have had a booster or two along the way. I get my titer checked every year. Also, I have been bitten by hundreds of bats in my work. Were any of them rabid? No, or my titer would be way high or I'd be dead. It is the same with most all of us working with bats (other than bat re-habbers, who must be really careful as they DO encounter rabid bats).

So, I offer no science on the topic, as it is limited. But I do offer my opinion...

If you are going to cave in a cave with scads of bats, there is a wildly remote chance that you will die shortly in a rather unpleasant manner. History shows that you won't, but it can happen. If this worries you, get the three-shot vaccine. It ain't cheap, at about $500, but this is a personal responsibily issue. If you think you need it, pay the price and get vaccinated. Get a titer check every two years or so to make sure it is still good. The booster, once vaccinated costs about $50.

All for now. I don't want cavers to think they shouldn't get the vaccine, but am just presenting some bits to help clarify the issue.

Cheers,

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Postby Squirrel Girl » Sep 18, 2005 7:09 am

Gee, where'd you get your booster? I paid $100 for my last booster.

The way I understand it is that if I got bitten by a suspected rabid animal, even with the pre-exposure shots, I still have to go off and get the post-exposure shots. But, yeah, I also know that bat handlers often get bitten without getting the post exposure shots. So what gives???

Thanks. You have the BEST bat pix. Love your avatar. Even if it's not as cute as a picture of your pet dead bat.
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Postby tropicalbats » Sep 23, 2005 1:43 am

Squirrel Girl wrote:Gee, where'd you get your booster? I paid $100 for my last booster.

The way I understand it is that if I got bitten by a suspected rabid animal, even with the pre-exposure shots, I still have to go off and get the post-exposure shots. But, yeah, I also know that bat handlers often get bitten without getting the post exposure shots. So what gives???

Thanks. You have the BEST bat pix. Love your avatar. Even if it's not as cute as a picture of you pet dead bat.


Skwrl Gyrl,

Howdy! I've been off the board for a couple of days writing too long emails.

Your first point is noted, as I believe I was thinking of my last titer check and not my last booster. I don't remember exactly, but yes, I think it was over $100.

So what gives with the idea that vaccinated people should still get a post exposure series after being bitten by a bat? Well, the fact is that this is true, but you are correct that we who get bat bites all the time don't follow this. If I followed this protocol, I'd have to get a multitude of post-exposure shots. The difference is this. I pretty much only handle free-flying or in-cave bats that can be assumed to be healthy. A random bat bite by a bat found crawling across someone's kitchen floor is a real danger. Yes, any free-flying bat can have rabies, as can any bat captured in a cave, but statistics show that vaccinated biologists aren't keeling over from the disease and so I just go with the odds. Follow the CDC guidelines, even if we who get the most bites do not.

Cheers,

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