I'm still not sure about the mechanics that lead to rabies being incurable. I know that it can be treated before any symptoms show up, but why is it that once symptoms show the person is a dead man walking?
2 Answers
This is because rabies is a viral infection of nervous tissue that propagates through peripheral nerves into the brain and causes brain tissue inflammation (encephalitis).
As long as the virus is in the brain there is no way to get rid of it. The main trade-off here is that everything that would kill the virus will be as (or even more) aggressive against the brain tissue, and impairment of the latter will lead to really heavy deficits in vital functions like breathing and thermoregulation.
The first manifestations of rabies are those due to brain damage. This means, the virus is already there and the brain is already fatally damaged.
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$\begingroup$ Ok, so the virus is already in the brain tissue if treatment isn't started. Thank you. $\endgroup$ Apr 12, 2012 at 16:42
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3$\begingroup$ @Robinabo - Well not exactly. The virus starts out infecting peripheral nerves, and takes advantage of the transport mechanisms to be transported up the PNS toward the CNS until it gets to the brain. You have a very limited window to receive treatment (anti-rabies vaccine). Once a human is symptomatic, odds of survival drop precipitously toward 0% (there are only one or two cases of humans that have survived a symptomatic infection). $\endgroup$– user560Apr 12, 2012 at 23:37
It may actually be curable, as shown by success stories involving the Milwaukee protocol in which the brain is effectively shut down to allow for the immune system to eradicate the virus. In most cases, however, it is fatal once symptomatic. Note that the Milwaukee protocol boasts an imporessive (sarcastic) survival rate of under 15%
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$\begingroup$ Interesting! But I can't see it being adopted with <15% survival (although this is better than 0% if no treatment is administered)! But work will undoubtedly continue. $\endgroup$– LukeAug 21, 2012 at 8:05
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$\begingroup$ Also, even if you survive, you'll likely still have suffered permanent brain damage. $\endgroup$ Sep 16, 2012 at 4:49
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$\begingroup$ It's a small price to pay, in most cases. $\endgroup$ Sep 16, 2012 at 6:43
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4$\begingroup$ The consensus among doctors and researchers is now that the Milwaukee Protocol not only only useless, it's worse than useless. E.g (one example of many) "The recommendations made by the Milwaukee protocol warrant serious reconsideration before any future use of this failed protocol." --Critical Appraisal of the Milwaukee Protocol for Rabies: This Failed Approach Should Be Abandoned $\endgroup$– iayorkJul 26, 2016 at 14:17
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$\begingroup$ I couldn't get that article through the paywall, so I wanted to add this non-academic article which explains some of the problems with the Milwaukee Protocol. $\endgroup$– AndrewJul 27, 2016 at 19:26