Rabies is so fatal because once the virus enters the nervous system and reaches the brain, it causes irreversible inflammation and nerve damage, for which there is no effective cure after symptoms begin. The virus hides inside nerve cells, making it nearly impossible for the immune system or medications to eliminate it. While dog bites are the most common source of infection worldwide, other animals such as cats, bats, monkeys, raccoons, and foxes can also carry and transmit rabies through bites or saliva contact with open wounds. Any mammal is a potential carrier, so all bites or scratches from suspicious animals should be treated as possible rabies exposures.