Fleas are very harmful to puppies & kittens. It will take more than a regular treatment to get rid of them if they are as bad as you think. Please do not bring him home with the fleas/ticks - bring him to the vet and let him do the treatment, especially because he's a pup. Make sure to ask the vet what he suggests to use as maintenance after the treatment. Also, ask about the area that you live in - if it's wet, grassy and has alot of trees - there's fleas outside just waiting for your new baby... I'd suggest not letting him outside until colder weather. After being infested with them his little body needs some time to get strong. Good Luck and Congratulations on your new puppy!!!!