Give them Revolution. Squirt it on the back of their necks. No more
fleas or worms.

Get rid of flea collars  they are a danger to cats due to the snag factor
Advantage works the best for fleas since they are in door cats
If they are on you.     You need to bomb the house  wash all clothes and pet
material make sure everything is off the floor and enclosed areas are opened
up to expose all of it
Out side  of your house  you can have treated to help cut out the problems