At the moment, my Tomato plants are just forming their second flower truss, so they are still immature as far as plants go, but they still need some attention to excess leaves and sideshoots. This is where hygiene comes into growing tomato plants, well more on the maintenance side of things. If you do it right, you should have a nice sharp knife, I use a Metallo 7020, a bottle of Methylated Spirits and some Cotton Squares, with the squares becoming alcohol type wipes. As you cut leaves from plants, wipe the blade of your knife on the wet wipe so you are not spreading anything from one plant to another.
It doesn't take long before you can tidy up a heap of plants using a sharp knife, plus your not spreading anything as you do it. How simple is that.