Not a teacher
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Hello, Tufguy
The problem with your original sentence is that it can be easily misinterpreted. In fact, it is just incorrect.
Once you have been bitten by a rabid animal it takes sometime symptoms to show.
This is how I understand your sentence:
A rabid animal bites me → time passes → symptoms appear.
Once symptoms have shown victims die within eight to ten days of being bitten.
This is how I understand your sentence:
A rabid animal bites me → time passes → I die.
In both sentences you refer to the time that passes between:
Being bitten and the presence of symptoms (in sentence 1).
Being bitten and death (in sentence 2).
Based on your second sentence in particular, I understand that after a
rabid animal bites me,
I die within
eight to ten days. This is incorrect, and this is what you need to fix in the first place. The information conveyed by your sentence is counterfactual.
Lyssavirus is complex enough to cause problems when you're trying to describe how it kills. There are two [simplification] stages that need to be considered and explained separately. Otherwise, the reader will be confused, and consequently misunderstand what you mean.
The first stage, which begins after the virus enters your organism, is when the virus travels through the nervous system to the brain. During the first stage, there are no symptoms.
The second stage, which begins after the virus enters your brain, is when symptoms appear, and Lyssavirus starts killing its host.
The second stage is, indeed, very short. However, the duration of the first stage can vary enormously depending on where you were bitten (basically, how "far" away from the head you were bitten).
Try to make it absolutely clear that you're referring to two different periods of time.
A rabid animal bites me → time (1) passes → symptoms appear → time (2) passes → I die.