This is because once symptoms are exhibited, the virus has infected the brain tissue, which is called encephalitis. At this point, seizures, a coma, and death, unfortunately, are soon to follow.
This disease is still not entirely understood but the symptoms are preventable. There is a vaccine for individuals who work in environments where they could contract rabies. If an individual is bitten by a rabid animal, they should see a doctor immediately to be given the rabies vaccine.