Sunday, June 29, 2008
Does anyone remember the old old Disney movie "Old Yeller"? I was just a kid when I watched this tear jerker, but what I remember most about it was that Old Yeller got rabies and died. Rabies was one of the first serious diseases I ever learned about as a kid. My first medical word was "hydrophobia".
In the U.S. and Canada, rabies is really rare. In Canada, only 24 cases of human rabies have occurred since 1924 and since 1970 six of the seven cases have been attributed to bats. In the U.S. 40 cases have been reported since 1990. Of those, 37 were caused by bats.
If a person is exposed to rabies, post exposure prophylaxis (PEP) is given. It consists of rabies immune globulin and a 5 dose series of rabies vaccine. An exposure is a bite, scratch or exposure of non-intact skin or mucous surface to saliva, tears or brain tissue. If the PEP is not given before the onset of neurologic symptoms, it will not work. After exposure, the usual incubation period for rabies is 20-60 days.
There is only ONE unvaccinated rabid patient that has survived. She was a 14 year old girl in Milwaukee who was diagnosed in 2004. She was placed in a chemical coma to slow down metabolism in the brain and given massive anti-viral medications and high dose Vitamin C. She was tested daily for levels of virus neutralizing antibodies in serum and over weeks she survived. The same protocol has been tried on other rabies victims without success.
So the take home message is that any contact with bats carries a risk of rabies. If you are bitten, immediately wash the wound with soap and water and capture the animal if it can be done safely. Local animal control services can assist and test the bat. The Emergency Department will evaluate regarding the need for PEP. Rabies is fatal but preventable with early preventive treatment.
Additionally, clinicians need to recognize that a majority of patients with rabies transmitted by bats might have no recollection of a bat bite so any patient with an unexplained acute, rapidly progressive viral encephalitis needs to have rabies in the differential diagnosis.
BTW...I re watched "Old Yeller" and it doesn't stand the test of time. It wasn't nearly as sad or shocking or interesting 40 (or more) years later.
Posted by Toni Brayer, MD at 10:57 PM