You've never seen a rabid human have you? But diseases have different effects on different species, since there are differences in biochemistry and physiology.
Still, the inhibitor must have been viral, since it is able to reproduce, which is evident from the way it spreads, consistent with a reproducing pathogen.
In World War Z, the disease was known as "African Rabies". I know of several diseases that change behaviour. Such as
Toxoplasma Syphilis is well known for causing an increased sex-drive if not treated (and eventual death due to brain damage).