I disappear if you say my name, what am I?

Question

I am 7 Letter word
Most Humans want me.
But they hate the first 4 letters of my name.
If you get the 2nd, 3rd and 4th letter you are sick.
The 5th, 6th and 7th letter are something with charge.
Who am I ?

Answer 1

Silence is the answer