The international study, launched at Penn State Eberly College of Science in the United States, examined microbiomes on 116 houseflies and blowflies from three different continents.
The results, published in the journal Scientific Reports, found that flies contribute to the rapid spread of germs during an outbreak of disease among people – something scientists have long thought.
Scientists found 15 instances of helicobacter pylori bacteria – which causes stomach ulcers – on Brazilian blowflies.
Donald Bryant, a professor of biotechnology at Penn State University, said: “We believe that this may show a mechanism for pathogen transmission that has been overlooked by public health officials.”
Researchers also examined the level of germs on individual areas of the fly, including the legs and wings.
Stephan Schuster, research director at Nanyang Technological University, said the fly’s legs transfer the most microbes from one surface to another.
Flies most likely pick up the bacteria from poo and decaying organic matter which they use to nurture their young, the study found.
“It may be that bacteria survive their journey, growing and spreading on a new surface,” Schuster said.
“In fact, the study shows that each step of hundreds that a fly has taken leaves behind a microbial colony track, if the new surface supports bacterial growth.”
“It will really make you think twice about eating that potato salad that’s been sitting out at your next picnic,” Professor Bryant said.
“It might be better to have that picnic in the woods, far away from urban environments, not a central park.”
Ana Carolina Junqueira, a professor of genetics and genomics at the Federal University of Rio De Janeiro, added: “This is the first study that depicts the entire microbial DNA content of insect vectors using unbiased methods.
“Blowflies and houseflies are considered major mechanical vectors worldwide, but their full potential for microbial transmission was never analysed comprehensively using modern molecular techniques and deep DNA sequencing.”
But the study also suggested that flies could help protect humans by acting as living “drones” or acting as early warning systems for disease.
Schuster added: “For one, the environmental sequencing of flies may use the insects as proxies that can inform on the microbial content of any given environment that otherwise would be hard or impossible to sample.
“In fact, the flies could be intentionally released as autonomous bionic drones into even the smallest spaces and crevices and, upon being recaptured, inform about any biotic material they have encountered.”
Source: The Sun