There is no oral method of keeping fleas off of animals. The issue your having is not so much treating the animal, as it is treating the area in which they live. You need to dust and clean your carpets and bedding for the animals every day. I assume you have dogs? They also need to be bathed every few days. Topical treatments from the vet will help kill off the ones on the animal, but if your not on top of vacuum every day on all of the carpets, you will have little success in ridding them of these blood suckers.
Here is a link on one of the many methods of removal of them. http://www.ehow.com/about_5405631_carpet-treatment-fleas.html
It works. We get them every year. Dog brings them in from barn from being around the horses. If we do not clean the carpets every few days it gets out of control on our dog very fast.
Oh we have them also.Very bad this year.I give my dog a bath everyweek now, and constantly cleaning the sofa, her little bed and still have them.Good luck!
Fleas can be pretty bad in Florida. I switched to Comfortis for my dog when I moved here, and it is very effective. But Woodbridge is right, you have to address the fleas in your environment as well.