I've been treating my cat with prinovox (same as advocate) for 3 months but we still appear to have fleas in the house. I've not seen any but my youngest dd seems to have been bitten quite a lot after cat slept on her bed so I'm guessing it's fleas :/ I've just used the last prinovox and vet is giving us stronghold to try next. Has anyone used prinovox/advocate and had fleas be immune?