@georgetakei Because the concept of "vampire bats" has never been heard of on Earth, right?
But wolves aren't really vampiric either. It wasn't really about that anyway. It was about them turning into a creature that is known to "live in the night" so to speak. Something that could be somewhat scary to people on principle if nothing else. The idea being the vampire could travel or hunt and they wouldn't even be able to recognize them.
@georgetakei Vampirism is a mosquito-borne infectious disease that affects humans and other vertebrates. Symptoms usually begin 10 to 15 days after being bitten by an infected Tepes mosquito.
(Haemophagia is a metabolically marginal diet—blood is notably short on nutrients!—so all actually-existing haemophagic species are highly specialized. I once did a BOTE calculation and worked out that a human-size vampire would need to bleed about one victim per hour completely dry to avoid starvation.)