hair comb used by many will effect the scalp?and produce dandruff?

I believe that the bacteria that causes some kinds of dandruff can be spread from person to person.. But MOST dandruff is caused by a non-contagious skin condition.... This is what I have heard but I don't have any documentation on this!

Yes bacteria causes kind of dandruff. They get spread from one person to other by contact. When a same comb is shared, or when people share the same pillow. so it must be avoided and extra care to be taken.

Dandruff is just dried skin on your scalp, you can't pass it from one person to another. I mean, if there was some on the brush, it could get onto someone else's hair, but it doesn't make them have dandruff. The main cause of dandruff is when you sweat a lot, I believe and then the sweat dries.