Tapeworms come from fleas. They probably won't catch from eachother directly, they get them from the fleas. Or eating prey (mice etc) that have fleas...
Make sure your cat(s) get treated with
a good anti flea med from the vet. Frontline or Revolution are top picks.
Second, make sure you treat your home, esp. carpet base boards
where the suckers love to live/breed...
Third, get the vet to give you Drontal - this will be in the form of
1 or 2 yellow pills, each cat has to have 2 doses, 3 wks apart.
Et voila - no more fleas, and no more tapeworm!!