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The Rabies Page

A Compendium of Information for Cavers about Rabies

The bottom line of the immense rabies literature is that no one is clearly
known to have caught rabies from breathing cave air. Rabies from bat bite or
scratch in a cave is equally rare and controversial.

From William R Elliott, Ph.D.:  (excerpted from a posting on CaveTex, Wednesday 21 April 1999)

I'm not an MD, but I have followed this subject of rabies in the scientific literature for years. The risk of rabies from caving is almost zero unless you actually handle lots and lots of bats without rabies vaccination. Cave and bat biologists don't even do that, usually. If you are going to handle bats, better get the human diploid rabies vaccination (maybe $100-200 cost). I know a grad student who failed to do this, even though he was handling bats while mist netting. He finally got bitten, and had to pay $2500 for post-exposure rabies treatments, which was necessary.

Perhaps 20 confirmed cases of bats passing rabies to humans (who died) were found in North America in the last few decades. See Bat Conservation International's web site http://batcon.org for details. None of these cases were cavers, and none were confirmed from cave situations. It's strange, but more than a few of these cases may have been caused by the silver-haired bat flying around someone's house. No evidence of a bite was found in most of those cases. This is a mystery. Most cases of human rabies were acquired from dog bites. That's why dog catchers and mammal biologists usually get vaccinated. In Texas skunks and foxes are a major wildlife reservoir for rabies, which gets passed sometimes to domestic animals. Dogs are the major reservoir. Texas raccoons rarely have rabies, while coons in the eastern USA often have rabies. Bat populations probably have far less than a 1% rabies rate.

If you want to know more about the two people who died of bat rabies in Texas in the 1950s, read my chapter on Conservation in the 1994 NSS Convention Guidebook, The Caves and Karst of Texas. It gives the history of bat protection in Texas, and some previously unpublished details about the mining engineer and the health dept. lab worker who died of rabies. The lab worker may have gotten infected in a cave, or in the rabies lab where he worked, or from an experimental live rabies vaccine given to him by his own physician.

The risk of getting rabies from walking into a bat cave and just breathing the air is probably very low for humans. A study of caged animals in Frio Bat Cave proved that they could catch rabies by the "aerosol route", without being bitten by a bat. But the animals were exposed for weeks in a hostile atmosphere, which included caustic ammonia vapors that probably weakened them.

What's the latest word on obtaining Rabies vaccinations?

According to Jim Kennedy at Bat Conservation International:

Talk to Sharon Mulligan at the Travel Clinic on the second floor of the north wing of the Austin Diagnostic Clinic off north Mopac in Austin. I don't know what the series costs, but the blood sample/analysis for the titer cost $35. It may be possible to announce the service, round up a bunch of other cavers who also need titer checks, and go in en masse. Get the titer check first, though. Your titer may be OK and you won't need the booster shot, which will save you a couple of hundred bucks.

I'm sure that other major cities have a similar program.

How effective is the Rabies vaccine at preventing Rabies?

One more thing about the rabies "vaccine" that needs clarified:

It DOES NOT prevent you from contracting rabies if you get bit by an infected animal. It merely reduces the number of post-exposure shots you need to three. Not only that, but various humans process the serum differently, so that one may have a high number of antibodies present after many years, while another may have a count next to zero after only a year. All wildlife professionals (including those of us that regularly handle bats) should get their titer level checked annually. This involves drawing a small blood sample, which is sent to a lab for analysis. Even if you have received the pre-exposure "vaccine", YOU SHOULD STILL GET THE POST-EXPOSURE TREATMENT IF YOU COME IN CONTACT WITH A SUSPECT ANIMAL!!! Rabies is a deadly virus, with no known cure. If you wait until symptoms start to show, it is too late for any treatment. If in doubt, get the shots.

Realistically though, like so others have already pointed out, your chances of contracting rabies from caving is practically nil. Unless you regularly come in DIRECT contact with mammals (particularly dogs and cats, but including bats to lesser degree), then don't bother with the "vaccine". It's not a catchall prophylaxis, and is unnecessary for general caving.

RABIES

by Alicia Wisener Gale
excerpted via OCR from an article which first appeared in The TEXAS CAVER June 1976

IMPORTANT NOTE:  This work is over 20 years old and some of the information regarding treatments and immunizations is out-of-date. Do not rely on it for accuracy when looking for or prescribing rabies treatment or immunizations.

Down in the dark of caves live the bats, and down in the dark of the bats lives a particularly nasty little virus of the Rhabdovirus group. It is the rabies virus. All warm blooded animals are susceptible to its infection; recovery from the disease in man is rare, almost non-existent.

Rabies in man is manifested in four stages: a short prodromal phase, a sensory prodromal phase, a sensory phase, a period of excitement, and the paralytic phase. The first, prodromal, usually occurs 14 to 21 days after infection and is symptoms are by malaise, anorexia, headache, nausea, sore throat, and/or fever. The patient later begins to show increasing nervousness and apprehension with lacrimation, pupil dilation, increased difficulty in swallowing, and perspiration. (The difficulty in swallowing due to terrifically painful muscle spasms of the throat led to the patients 'fear of water' or drinking, from which came the name 'hydrophobia'. ) The excitement phase occurs 3 to 5 days from onset and is characterized by seizures, convulsions, and death. If the patient survives the third phase, he becomes listless, stuporous, and finally comatose, followed by death. All infections of rabies were held to be fatal until 1970 when a single recovered case was documented.

Bats infected with rabies react differently than their human, spelunker-type counterparts. Bats can recover from rabies since, in some peculiar way, the virus adapts itself in a nonpathogenic manner to the chiopteran salivary glands. Vampire bats transmit rabies for months without ever showing a sign of the disease. Even if you catch the little rascal who nipped you, its brain tissue may not show rabies virus even though yours will shortly. Almost half the infected bats showed no inclusion (Negri) bodies which is a positive test for rabies and many harbor the virus only in their salivary glands and brown fat. Remember, you can't detect most viruses microscopically. Since 1964 there have been 321 cases of rabies in bats reported. When one considers the difficulty of determining bat rabies, the number of unchecked bats, and the number of bats whose bite could mean rabies for a caver, it gets a little spooky.

Since 1950 there have been six human rabies cases attributed to bat bites. Bats spread the virus in two ways: entrance of rabies virus containing saliva into human circulation via a bat bite and, aerosol transmission of the virus in bat infested caves.

The rabies virus was recently discovered in colonial and non-colonial frugivorous and insectivorous bats in the US. Bats are able to transmit rabies to humans and quadruped mammals. The virus does occur in Mexican Freetailed bats and healthy bats of this genus show a large percentage of antibodies against the disease. Infection of the Mexican Freetail may be due to the fact that they winter in Mexico with Vampire bats, especially notorious for their rabies carrying abilities. Transmission from one species to another accounts for this. If you are bitten by a bat, cleanse the wound thoroughly. No wound closures are advised. Next, resign yourself to the rabies series since, if your bat is infected, there's only a 50:50 chance of proving it, meaning that you have a 50:50 possibility of getting it, even if the bat proves negative. This means 14 to 21 single daily injections of the infamous "belly-type". If you are over 15 years of age and are given heterologases antirabies series, you run a 46% chance of developing serum sickness. Happily though, a new human antibody-antisera that doesn't provoke allergic reactions is now being evaluated for human use. Oh yes, you should also get a tetanus shot if you're bitten.\par Now, since the aerosol transmission was proven, a caver is faced with the unpleasant thought of waking up some two weeks after a caving trip with malaise, anorexia, headache, et cetera. No case of human rabies by aerosol transmission has been documented to date, however. Unfortunately, by this prodromal phase, it's probably too late for the rabies series.\par An alternative to the rabies series (post infection prophylaxis) is the 'pre-exposure' immunization. Two types of vaccine are now used in the US: duck embryo vaccine (DEV), and nerve tissue vaccine (NTV). DEV is prepared in embryohated duck eggs infected with the Pasteur rabbit-brain-fixed-virus and is then inactivated with propbio lactone. NTV is a rabbit brain tissue preparation infected with a fixed virus and inactivated by phenol and incubation at 37C, or UV irradiation. The NTV are dangerous since the foreign rabbit brain material may sensitize the person vaccinated and produce allergic encephalitis and paralysis. Sometimes the chances of getting these side effects are greater than the chance for contracting rabies. All of this is due to an antigen antibody reaction which reacts with the patient's brain antigen and causes inflammation and degeneration. Duck embryo is most often used in the US. It markedly reduces chances for encephalitis, but anaphylactic reactions and post treatment paralysis have been reported. DEV is given by injection on two possible schedules: two doses, one month apart followed by a third, six months later, or three weekly injections with a fourth dose three months later. Booster immunization should be obtained every two to three years and effectiveness confirmed by a serum-neutralization test.

The vaccine is available from the State Health Department, and in some instances, the County or City Health Units, usually free of charge. Your family doctor can also prescribe it for you, at a higher cost of course, from your favorite drugstore.

The injections are virtually painless, but some recipients report very minor itching and inflammation in the area of the injection for several days following. Your lymph glands will defiantly swell, and any blood tests taken for the next week or so will show high levels of white blood cells.