That would still be hard to control for. I believe I recall reading that a T. gondii infection is something you get for life. Even if you adopt kittens from your local shelter at 8 weeks old, and then keep them indoors for the rest of their lives, they may have come in contact with rodents at some point before they made it to the shelter.
Hell, regardless of that, many homes in many places suffer rodent infestations at some point in time. Even if you get the exterminator in, it might be too late. This summer we bought a new house, and a few nights in, our (fully indoor) cat showed up to our bedroom, a (still breathing) mouse hanging from his mouth. So much for keeping him away from rodents.
The shedding of oocytes is how humans become infected. This is supposed to be stopped by the cats immune system a few weeks after initial infection. It is possible it could reoccur later if the cat's health changes as other life cycle stages exist in the cat.
Hell, regardless of that, many homes in many places suffer rodent infestations at some point in time. Even if you get the exterminator in, it might be too late. This summer we bought a new house, and a few nights in, our (fully indoor) cat showed up to our bedroom, a (still breathing) mouse hanging from his mouth. So much for keeping him away from rodents.