Someone who has the virus could stroke their cat, thus turning the cat into an infection vector. Cat goes roaming. Stranger strokes cat. Stranger sticks unwashed hands into gob, up nose and up bum, as we all do after petting a strange unknown mammal. Virus spreads. Same applies to dogs.
I can definitely see a pet as a infection vector. Whether or not a cat can actually get the virus I do not know. See attached advice from the BVA (British Vet's Association)