Madinah Nalukenge, who did not study beyond grade school, is part of a growing trend in Africa where more women are running businesses on a scale that was unthinkable a generation ago. Africa now has the highest growth rate of female-run enterprises across the world, according to the World Bank. About 63 percent of women in the non-agricultural labor force are self-employed in the informal sector in Africa, more than twice the worldwide rate, according to World Bank data.