Yes, it would still be a good idea to disinfect it periodically.
To disinfect, simply put the wet sponge in the microwave for 2 minutes or you could run them in the dishwasher and it will come out good as new!
*Please note: The amount of time you microwave the sponge for would vary with the power of your microwave. If it is a high power model, please decrease the time you disinfect your NanoSponge.
Another way would be to soak your sponge in white vinegar (full strength) for 5 minutes. Overnight is even better! Then, let the sponge air dry; in the sun if possible.
Try It Out! Leave it out in the sun for a day or two (without any additive). Some studies show that the strong UV can help eliminate viruses/bacteria, etc.