Sounds like "Favus", a fungal infection. An over the counter anti-fungal cream, such as for athelete's foot or vaginal yeast infection (Clotrimazol) can be used. The fungus can spread to you, so use gloves. My previous rooster had it, so I would go out at night, when everyone was sleeping, and apply the cream to his comb and wattles as best I could, even the areas that weren't white, as a preventative. Wasn't easy. I can't say I cured it, but it never seemed to spread or to be a problem.
Like all web-based health resources, if you look hard enough, you'll convince yourself that this is Dooms Day for your flock. I suppose if living/housing conditions are bad enough, it could spread and prove fatal (infect skin and lungs). My flock is practically free range (huge electric net fenced yard), so I wasn't overly concerned. I suppose if Elvis had been feeling poorly, in addition to the white dusting on his comb and wattles, I would have been more actively worried.
Good luck!
