Here's how to protect them:  

• The way the fungus spreads from nail to nail is usually with nail files, clippers, and cuticle cutters. Never use the same set of tools on the infected nails that you use on the healthy nails. You need TWO sets.
• If you go to the salon for pedicures, don't let them use the same set on all your nails. Best is to bring your own set at least for the infected nails.
• Also, it helps to keep your feet clear of all athlete's foot (fungus) too. Use Lamisil cream (no prescription needed) all over the bottom of the foot and between the toes at least weekly to prevent athlete's foot and fungal spread.

See Dr. Irwin's new article:  Are There Skin Care Product Alternatives to Botox and Lasers?