I have 8 stray ferral cats that have shown up at my place and are all living on my deck. They showed up a couple at a time, I swear they tell other cats where the food is. I was pretty sure they were wormy, skinny cats with big bellies. I picked up cat de-wormer at Walmart, it was only a couple of dollars. You can put it on their food, directions are right on the bottle. Ferral cats are not picky about their food, I feed them dog food, scraps and left overs.
I can now pet each one of them and even pick up a couple of em. Five of them are females which I will be getting spayed next week, along with vaccinations.