The answer to that question is yes. During the winter cats will not get the fleas from outside (depending of course where your live) so usually they will still have them because of what is left inside the house. Our vet suggested we use Advantage for about 8-10 months and then we would be flea free so to speak.

What do they look like? Well, you' have probably seen them - tiny, quick creatures that scurry through your cat's fur, feasting on her blood, and causing painful itching - so bad that kitty may scratch herself raw in seeking relief. If you have a bad flea infestation in a multiple-cat household, you've probably been bitten yourself by these voracious feeders, and you may even have seen them hopping through your carpeting. (Did you know a flea can jump 33 cm. in one leap - over a foot?) . Nevertheless,  cat flea control is not only possible, it is actually quite easy.  The most common flea which feeds off cats, dogs, and humans, is the Ctenocephalides felis. If you observe your cat scratching and aren't sure if fleas are the cause, use a flea comb on your cat and observe the tiny black dots that emerge on the comb - we commonly call it "flea dirt," but in reality, it is the excrement the flea leaves. Smash some with a damp paper towel, and it will turn red - that's the residue from your cat's blood - and a warning that cat flea control is indicated.
As if the itching and stinging weren't enough, fleas also transmit other conditions which can even have a more deleterious effect on your cat's health.

If your cat does have a problem with fleas then it is best to go directly to your veterinarian. He will have a choice of products for you to choose from. These flea treatment products may come in the form of soaps, sprays, sticks, powders, and dips. Your veterinarian will also lay out a treatment procedure for your cat to follow as well as a worm check.