Flies in urban areas are far more dangerous than creatures in rural areas.
The insects get the microbes from feces and rotting animals upon which they lay eggs (maggots) that hatch and use the mouldering filth as a food source.
Dr Stephan Schuster, research director at Nanyang Technological University, Singapore, found their legs carry most of the narly nasty. Even a micro-second landing on food leaves behind large loads of pathogen.
Hey Sheldon, still wanna eat outside?