Hi this article explains some things about
the tick saliva.
/www.ncbi.nlm.nih.gov/pmc/articles/PMC5479950/Its my feeling that even if the tick isn't fully engorged, it has already gone through the process of its own saliva mixing with hosts blood when it first attached to the host.
So I would think the bacteria/pathogens/neurotoxins may be transmitted even if a tick is not engorged.
My point being once the tick has started to attach to the host , it can transmit the pathogens.
Hope others chime in on this. Take care.