1. Toxicara

2. generally, carnivores are more likely then herbivores to carry things which can be transmitted to us. So in that respect, cat poo is not the same as horse manure.

There again, your cats will be depositing across the garden. So if you scoop up a lump from where you're about to plant out some seedlings, it's academic as to whether you sling it on to the compost heap or into the hedge.

But I wouldn't put large amounts there - find some other way to dispose of the contents of the litter tray.