CAPCvet.org is a great reference to see maps for the prevelance of different parasites in your area.  Think your cat can not get worms because they are indoors? Did you know 15% of potting soils have roundworms in them?  We all know cats like to play around in those.  And with 40 cases of blindness last year in children caused by this parasite it is no wonder veterinarians harp on year round prevention for both dogs and cats. Also Florida had more diagnosed heartworms than any other state. This stuff is getting easier to prevent.  A lot of the products even have something to kill our "super" fleas here which are more resistant than fleas in other states.  Check out the prevelance maps here: http://www.capcvet.org/parasite-prevalence-maps/ and schedule your pet to get tested if it has been over six month.  Call 407-330-PETS!