I don't agree with this analogy at all. You are characterizing ignorance as a substance that propagates under certain conditions while I see ignorance as an absence of something, that something being knowledge. The default state of a room is to be moldless, but ignorance is the default of humanity. One is born in this world ignorant of language, social norms, basic arithmetic, even the knowledge of walking. The only way to dispel ignorance is to pursue knowledge. But this quest is ultimately a futile one. The rate in which articles are being published in academic journals is greater than the rate in which one can consume them. Now, more than ever, it is impossible to know everything. But just because the quest is a futile quest doesn't mean that it is a meaningless one. I cannot articulate this feeling well, but I believe that the pursuit of knowledge should be done for its own sake.