" human blood donors, " - this is a problem! How many people are donating blood and don't even know they have bartonella to pass on?
The only vector borne infection that the blood supply has ever been tested for is Babesia - for the rest of those infections (Lyme, Bart, RMSF and others) the Red Cross only relies on patient questionnaires. So, if the person doesn't know they have the infection(s), then they are allowed to give blood (and donate organs!!).
I was one that regularly donated blood until I realized I had infections that I was likely passing on! Not once was I ever asked (in person or on a questionnaire) if I had Lyme or other infections like that. I donated blood for many years too.
But no longer, and I tell people who ask, why. I also encourage people with Lyme to not donate organs, as these infections can be passed that way as well.