At an abandoned blown-up nuclear plant a curious person who illegally visited the site stepped into a bunch of psilocybes. He had an athlete's foot. Due to the radiation their DNA was mixed up with the funghi on his foot, resulting in Trichophytons that produced psilocybin. When the infection spread, it became a problem in public changing rooms, with addicted persons licking infected people's feet. So a vaccine was invented. Clever drug lords began to hire children in the third world, to infect them, and then harvest the eschar. With the money the children earned they could afford nutrition, medical treatment and education. And so finally, world-hunger ended.