If you wish to encounter them, best bring a fast mount and rare flowers. Eat the flowers while running near the walls, then lose aggro debuff and turn around to pick them off. They have low base dmg and don't seem to infect you while mounted like bats can.
This thing CAN HANG FROM CEILINGS! Scared the shit out of me when i was walking in a cave and 2 fell from the ceiling. Watch out for the mega rabies as it will drain your health. Make spare beds when in the cave to save your stuff if you die. Carry antidote as well as a saving grace.