Cat feces can carry a variety of diseases that can be transmitted to humans as well as various parasites. I would certainly use gloves when working in this area and wash well after any gardening activity. I would also be less inclined to grow edible plants in this area until I was sure any remnants of the cat waste were completely removed and any pathogens neutralized. Applications of compost will be good for that, as the soil microorganisms that are active in conditions that promote a lot of organic matter - like the compost - will typically destroy/consume pathogenic organisms.