We have 2 cats and 2 children; the cats seem to have a constant flea infestation, despite the fact that we treat them (with collars/ tablets) every other week. It is the bane of DH's life, as they only seem to bite him and 4yo DS1 (the hairy people basically). DS2 (3yo) and I remain unbitten, thankfully.
Now DS1 is a rather hairy little boy, bless him, and the growth on his back is particularly luxuriant. This is where the fleas always bite him 
I'm tempted to shave his back, but that would be wrong, wouldn't it. Tell me that it would be wrong......