Ticks are nasty little buggers even thinking about one makes you itch.
Prevention is better than cure when it comes to Babesiosis/Biliary/Bosluiskoors. Treatment can be very expensive and not only that if caught too late even with treatment this could still be fatal for your pet.
Ticks like to breed, breeding is a cultural habit for them 
, giving preventative treatment does not only protect your pet, but it also helps to stop the life cycle of the remaining ticks!