So here's the thing I'm considering introducing vampires into my story the idea is they are like rabies but unlike rabies the victims maintain their personalities but display enhanced sadism and lack of empathy. Other than that the infected is basically the same person able to form relationships (with other vampires) like a human would but anyone else is just automatically perceived as food. Is it possible to explain this in a way that makes it believable? Also my story takes place in modern times and vampirism is treated very seriously for example refugees are brought in and one is suspected of being a vampire and my main character goes and kills them all out right his reason being "Even if just one slips through the cracks we could be looking at an outbreak in just a matter of weeks!" Is this an extreme reaction and is it too sensitive to use?