Jayne Cravens, an expert in development studies and online volunteerism, provides a long list on her website of the damage suffered in developing regions due to rumor, superstition, and urban legends. One story describes an African village that could no longer sell their ginger crop because of rumors that one could be infected with HIV through their produce.
What becomes clear after a perusal of her list, is that these rumors and superstitions are reflective of an inefficient information system. The problem is that this is a huge obstacle to development and the creation of wealth.
As noted in the World Bank's "Where is the Wealth of Nations" report, most of the "wealth" in the developed world is intangible, existing in institutions and rule sets. The most interesting part of this is that this intangible capital is so vital because it actually allows the creation of more wealth. Think of the patent office and the court system that enforces copyrights: this is a system designed to encourage creativity and invention, which in turn enriches the whole society. In a cournty with no protection for inventors, there is little incentive to work hard at developin anything new and useful. The bottom line is these institutions are crucial for the developing world to achieve a better state. What's left to discover is how much this inefficient information distribution system (rumors and superstitions) hampers the development of these economic and social institutions and rule sets.