How is rabies introduced in the first place?

[Life Forms Etc.]

I know that it is transmitted by body fluids, scratch or bite. Some animals that are high on the carrier list are not carnivorous so how do they become victims to begin with? Example: Bats I can understand once contracted it could easily spread as they are communal and often live in numbers in tight quarters but, how does the first bat become infected when they aren't likely to go after rabid animals? Nor are they scavengers like skunks or fox.